Opioid epidemic

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Opioid_epidemic 

The opioid epidemic, also referred to as the opioid crisis, is the rapid increase in the overuse, misuse or abuse, and overdose deaths attributed either in part or in whole to the class of drugs called opiates or opioids since the 1990s. It includes the significant medical, social, psychological, demographic and economic consequences of the medical, non-medical, and recreational abuse of these medications.

Fentanyl. 2 mg (white powder to the right) is a lethal dose in most people.^[1] US penny is 19 mm (0.75 in) wide.

Opioids are a diverse class of moderate to strong painkillers, including oxycodone (commonly sold under the trade names OxyContin and Percocet), hydrocodone (Vicodin, Norco), and fentanyl (Abstral, Actiq, Duragesic, Fentora), which is a very strong painkiller that is synthesized to resemble other opiates such as opium-derived morphine and heroin. The potency and availability of these substances, despite the potential risk of addiction and overdose, have made them popular both as medical treatments and as recreational drugs. Due to the sedative effects of opioids on the respiratory center of the medulla oblongata, opioids in high doses present the potential for respiratory depression and may cause respiratory failure and death.

Opioids are highly effective for treating acute pain, but there is strong debate over whether they are effective in treating chronic or high impact intractable pain, as the risks may outweigh the benefits.

North America

United States

Main article: Opioid epidemic in the United States

See also: California opioid crisis

From 1999 to 2021 it is estimated 645,000 Americans have died from opioid use. The number of overdose deaths involving opioids in 2021 was ten times what it was in 1999. What the U.S. Surgeon General dubbed "The Opioid Crisis" was theorized to have been caused by the over-prescription of opioids in the 1990s, which led to the CDC Guideline for Prescribing Opioids for Chronic Pain, 2016 and the resulting impact on medical access to prescription opioids "outside of active cancer treatment, palliative and end of life." Opioids initiated for post-surgical pain management have long been debated as one of the causative factors in the opioid crisis, with misuse/abuse estimated at 4.3% of people continuing opioid use after trauma or surgery.

When people continue to use opioids beyond what a doctor prescribes, or when opioids are over-prescribed, whether to minimize pain or induce euphoric feelings, it can mark the beginning stages of an opiate addiction, with a tolerance developing and eventually leading to dependence, when a person relies on the drug to prevent withdrawal symptoms. Writers have pointed to a widespread desire among the public to find a pill for any problem, even if a better solution might be a lifestyle change, such as exercise, improved diet and stress reduction. Opioids are relatively inexpensive, and alternative interventions, such as physical therapy, may not be affordable.

Opioids were involved in 80,411 overdose deaths in 2021, up from around 10,000 in 1999.

In 2017, around 100 million people or a third of the U.S. population was estimated to be affected by chronic pain at any given time. This led to a push by drug companies and the federal government to expand the use of painkilling opioids. In the 1990's, initiatives like the Joint Commission began to push for more attentive physician response to patient pain, referring to pain as the fifth vital sign. This exacerbated the already increasing number of opioids being prescribed by doctors to patients.

Between 1991 and 2011, painkiller prescriptions in the U.S. tripled from 76 million to 219 million per year. In 2016, more than 289 million prescriptions were written for opioid drugs. This was exacerbated by the aggressive and misleading marketing of drug makers, e.g. Purdue Pharma. Purdue trained its sales representatives to convey to doctors that the risk of addiction from OxyContin was "less than one percent."

Mirroring the growth of opioid pain relievers prescribed was an increase in the admissions for substance abuse treatments and opioid-related deaths. This illustrates how legitimate clinical prescriptions of pain relievers were diverted through an illegitimate market, leading to misuse, addiction, and death. With the increase in volume, the potency of opioids also increased. By 2002, one in six drug users were being prescribed drugs more powerful than morphine. By 2012, the ratio had doubled to one in three. The most commonly prescribed opioids have been oxycodone and hydrocodone.

The epidemic has been described as a "uniquely American problem". The structure of the US healthcare system, in which people not qualifying for government programs are required to obtain private insurance, favors prescribing drugs over more expensive therapies. According to Professor Judith Feinberg in 2017, "Most insurance, especially for poor people, won't pay for anything but a pill." Prescription rates for opioids in the US are 40 percent higher than the rate in other developed countries, such as Germany or Canada.

While the rates of opioid prescriptions increased between 2001 and 2010, the prescription of non-opioid pain relievers (aspirin, ibuprofen, etc.) decreased from 38% to 29% of ambulatory visits in the same time period, and there has been no change in the amount of pain reported in the U.S. This has led to differing medical opinions, with some noting that there is little evidence that opioids are effective for chronic pain not caused by cancer. Access to prescription opioids began to tighten up after 2010.

Hydrocodone, one of the most popular opioids

The opioid epidemic affects women and men differently. For instance, women are more likely than men to report recent and non-recent prescription opioid use. Women are also more likely to have chronic pain than men are. In cases of domestic abuse and rape, women are prescribed pain medicine more than men. During pregnancy, women may use prescription opioids to help with pregnancy pain, especially with post-pregnancy pain. The number of women who died from opioid pain relievers increased 5 times from 1999 to 2010. To help stop the spread of opioid abuse in women, it is advised that women are educated on the drugs that they are taking and the possible risk of addiction. Alternatives should always be used when possible in order to prevent addiction.

Most research gone into understanding the epidemic is mostly focused on females, specifically anticipated mothers. Women are at the greatest risk for opioid addiction compared to men. Usually, opioid misuse in women stems from unused prescription drug hoarding, the dependence of the drugs and higher pain levels compared to men. Women are less likely to report opioid misuse in contrast to the male population. Analyzers of the epidemic stress that their main concern is the female victims, and studies tend to neglect the male population, when over 70% of prescription drug intake and overdose, happen to males.

Adolescents can become easily addicted to opioids. Even before their teenage years, children go through the rapid growth of their reward center, the Mesolimbic pathway. The development of the Mesolimbic pathway allows children to be easily satisfied by small rewards to encourage learning, motivation, and acceptable behavior. This growth peaks in their adolescent years, and they start to feel a need for larger, more meaningful rewards, such as psychoactive substances which produce reward signals through direct receptor binding. Teens have an underdeveloped prefrontal cortex which governs impulse control and decision making. The combination of underdeveloped prefrontal cortex and a rundown reward system can lead to adolescents with addictive seeking behaviors and higher susceptibility to the neurological changes developed in substance use disorder (SUD). The Centers for Disease Control and Prevention estimates that In 2018, over 53 million people aged 12 years and older in the United States, reported the misuse of prescription drugs.

A 2020 review of the opioid epidemic in pediatrics stated that there were 4,094 opioid overdose deaths in people ages 14–24 in 2017. Teens commonly use opioids as recreational drugs, instead of what they are supposed to be used for, pain management. Centers for Disease Control and Prevention says that for every opioid death of a teen there are 119 emergency visits and 22 treatment admissions related to opioid abuse. Half a million teenagers in 2014 were reported as non medically prescribed opioid users and a third of those as having a substance use disorder (SUD).

Family is widely discussed as an influence for factors affecting adolescent opioid misuse behavior and in the treatment of adolescent opioid misuse. Family involvement has been shown to be effective in decreasing substance use in adolescents by addressing family risk factors that may be contributing to an adolescent's substance use. Easy accessibility is a risk factor. The late 1990s, increases in opioid recommendations from pharmaceutical companies created an abundance of prescription painkillers in adult households. If family members are taking opioids for pains or have taken them in the past and did not dispose of them correctly or do not protect them properly, it can make it easy for adolescents to get their hands on them.

Proper disposal of these drugs is crucial to reducing adolescent misuse. A national insurance cohort reviewed almost 90,000 opioid prescribed patients, 13–21 years old, and found that 5% continued to fill their prescription 90 days or more after surgery. Medicine take-back programs are the most recommended and regulated disposal method by the United States Drug Enforcement Agency, although, it is not guaranteed that the prescribed patient will comply with this recommendation. There are eight different at-home drug disposal products on the market but none of them is federal agency approved or in the process of being evaluated. The main concern of proper opioid disposal is trash and sewage disposal that create pharmaceutical pollution and still grants access for adolescents with substance use disorders.

Youth are at a heightened risk of developing opioid addictions, and treating youth opioid use disorder is more difficult than it is for older individuals. A systematic review of the epidemiological literature has found that adolescents and young adults consistently have shorter retention times in medication treatments for opioid use disorder than do older adults. This is why it is important for schools to implement effective strategies and programs to teach young children about the dangers and consequences of opioid misuse. Although the retention time of adolescents is much lower than adults, educating them from a younger age on opioid misuse should help keep children away from these drugs.

In 2018, there was a lack of appropriate treatments and treatment centers across the nation. In 2018, big cities like New York City were lacking in treatment services and health offices as well as small rural areas. Another reason the opioid epidemic is hard to combat is due to available housing being limited to recovering addicts. Having limited housing makes it easy for recovering substance users to return to the environments and relationships that promoted drug misuse.

Jobs for recovering addicts can be difficult to find. Individuals with substance use disorders that have criminal records have a more difficult time finding jobs once they leave recovery. Having to combat job insecurity can lead to stress, which can cause someone to relapse. "Wraparound services", or programs that provide services for patients who have just come out of rehabilitation centers or programs, are rare to non-existent, and are a contributing reason as to why the opioid epidemic has gone on for so long.

Public policy response

Further information: Anti-fentanyl legislation in the United States, State government response to the opioid epidemic in the United States, and United States sanctions against China

The 2019 lawsuit filed by the state of Oklahoma against Purdue Pharma was the first significant step in prompting public action toward ending the opioid epidemic. The state of Oklahoma argued that Purdue Pharma helped start the opioid epidemic because of assertive marketing and deceptive claims on the dangers of addiction. One of the marketing strategies was to redefine "substance use disorder" as "pseudo addiction".

In 2019, Purdue Pharma agreed to settle and pay 270 million dollars to the state of Oklahoma that would go towards addiction research and treatment. The settlement could indicate a win for other states that have taken legal action against similar opioid manufacturers. Specifically, states like California are raising similar claims that Purdue Pharma marketed the drug Oxycontin as a safe and effective treatment, which led to the opioid crisis leaving thousands dead in California from opioid overdoses.

Treatment within legal landscape

Title II of the Comprehensive Drug Abuse Prevention and Control Act of 1970, otherwise known as the Controlled Substance Act, established five drug schedules to regulate and control their manufacture and distribution. In 2017, President Donald Trump officially declared the opioid crisis a "public health emergency." In 2018, the United States federal government enacted the SUPPORT Act which aims to help Americans gain access to opioid addiction treatment and help and reduce the amount of opioids prescribed.

Other efforts include enacting legislation that provides funds from the Department of Health and Human Services to help support the creation and use of Syringe Services Programs. From 2019, legislatures have started to advocate for the implementation of supervised injection sites as another way to help the opioid crisis and reduce harm. In 2021, the United States Court of Appeals for the Third Circuit held that supervised injection sites violate the Federal Crack House Statute.

Safe injection sites

Safe injection sites, also known as supervised injection sites are designated facilities where individuals can use pre-obtained drugs under the supervision of trained medical staff. These sites are designed to reduce the health and societal impacts of drug use by providing a controlled, hygienic environment for drug consumption. The primary goal is to prevent overdose deaths through immediate medical intervention and to reduce the transmission of infectious diseases such as HIV and Hepatitis, by offering sterile injection equipment. These sites often provide a range of services, including access to addiction treatment, healthcare, and social support systems, acting as critical points of contact for individuals who might otherwise be disconnected from the healthcare system.

The concept of safe injection sites first emerged in Europe during the 1980s, with Switzerland opening the first such facility in 1986. This initiative was driven by rising heroin use and its associated public health crises. Over time, numerous studies have documented the benefits of these sites, including reductions in overdose deaths, lower rates of disease transmission, and improvements in public safety. These findings have contributed to the gradual adoption of safe injection sites in various countries.

In the United States, the opioid crisis has reached unprecedented levels, prompting a growing interest in harm reduction strategies such as safe injection sites. Despite facing significant legal and political challenges, several cities have taken steps toward implementing these facilities. The initiative has faced considerable opposition and legal hurdles, reflecting the contentious nature of the issue.

In 2021, New York City became the first city in the US to open authorized overdose prevention centers. Other cities, including Seattle and Denver, have explored or implemented similar measures, reflecting a growing recognition of the need for innovative approaches to address the opioid crisis. These initiatives often receive support from public health advocates and some local governments, who argue that safe injection sites are a pragmatic and humane response to a complex public health issue.

In 2023, the U.S. government took a significant step towards evaluating the effectiveness of safe injection sites. It approved funding for a study with a $5 million grant from the National Institute on Drug Abuse to measure the impact of these sites on overdose prevention, health care costs, and community safety. The study, conducted by New York University and Brown University, focused on two sites in New York City and one in Providence, Rhode Island. Researchers enrolled 1,000 adult drug users to assess the sites' effectiveness in reducing overdoses and estimating potential savings for the healthcare and criminal justice systems.

According to medical professionals, supervised injection sites are effective in reducing overdose deaths and the transmission of infectious diseases. These sites have been legally operating in Europe, Canada, and Australia since 1986, and have been associated with significant public health benefits. For example, a 2022 study of a supervised injection site in Vancouver, Canada, found a 26% net reduction in overdose deaths in the area surrounding the site. Despite these benefits, the U.S. Department of Health and Human Services has stopped short of supporting supervised injection sites, and legal challenges have hindered their implementation in many cities .

in 2024, the city of Providence, Rhode Island, approved the state's first safe injection site. This site, set to operate openly, became the only such facility in the U.S. outside of New York City. The approval came more than two years after Rhode Island authorized overdose prevention centers, highlighting the state's commitment to innovative harm reduction strategies. The Providence Center, run by the nonprofit Project Weber/RENEW and VICTA, aims to provide comprehensive services, including drug-related resources, case management, and housing support. This initiative reflects a broader trend of states and cities exploring the potential of safe injection sites to address the opioid crisis, despite facing resistance and legal challenges.

Despite the documented benefits and support from certain quarters, the establishment of safe injection sites in the US remains highly controversial. Opponents argue that these sites may enable drug use and attract crime, while proponents contend that the evidence from other countries demonstrates significant public health benefits.

Canada

A Naloxone injection kit at a train station in Calgary, Canada

In 1993, an investigation by the chief coroner in British Columbia identified an "inordinately high number" of drug-related deaths, of which there were 330. In 2016, there were 2,861 opioid related deaths in Canada. In 2017, there were 1,473 deaths in British Columbia and 3,996 deaths in Canada as a whole. Between 2016 and 2022 Canada saw a two and a half fold increase in the per capita rate of opioid related deaths, reaching 20.3 per 100,000 population per year, with 1,904 deaths reported in the first 3 months of 2023 alone.

In 2015, Canada was identified as the second-highest per-capita user of prescription opioids, behind the United States. In Alberta, emergency department visits as a result of opiate overdose, attributable to both prescription and illicit opioids, specifically fentanyl and fentanyl analogues, rose 1,000% in the previous five years. The Canadian Institute for Health Information found that while a third of overdoses were intentional overall, among those ages 15–24 nearly half were intentional. In 2017, there were 3,987 opioid-related deaths in Canada, 92% of these deaths being unintentional. The number of deaths involving fentanyl or fentanyl analogues increased by 17% compared to 2016.

Between April and December 2020, there was an 89% increase in opioid related deaths in comparison to 2019. Saskatoon, Saskatchewan experienced a record month in opioid overdoses in May 2020 caused, authorities explained, by a combination of ever-amplifying toxic drugs and the COVID-19 pandemic's quarantine keeping individuals from family and needed mental health services. Over 28,800 Emergency Medical Services (EMS) responded to possible opioid related health crises between January and December 2020 after the COVID-19 pandemic began. In May 2020, Medavie Health Services provided over 250 ambulance services for overdoses, administering the opioid antagonist nasal spray Narcan (naloxone) in record numbers.

North America's first safe injection site, Insite, opened in the Downtown Eastside (DTES) neighborhood of Vancouver in 2003. Safe injection sites are legally sanctioned, medically supervised facilities in which individuals are able to consume illicit recreational drugs, as part of a harm reduction approach towards drug problems, which includes information about drugs and basic health care, counseling, sterile injection equipment, treatment referrals, and access to medical staff, for instance in the event of an overdose. In 2017, Health Canada licensed 16 safe injection sites nationally. In Canada, about half of overdoses resulting in hospitalization were accidental, while a third were deliberate overdoses.

In 2012, OxyContin was removed from the Canadian drug formulary, and medical opioid prescription was reduced. This led to an increase in the illicit supply of stronger and more dangerous opioids such as fentanyl and carfentanil. In 2018, there were around one million users at risk from these toxic opioid products. In 2012 in Vancouver, Jane Buxton of the British Columbia Centre for Disease Control joined the Take-home naloxone program to provide at risk individuals medication that quickly reverses the effects of an overdose from opioids.

Outside North America

Main article: List of countries by prevalence of opiates use

In 2023, opioid seizures by authorities in Africa accounted for half of the global seizures of opioids, particularly tramadol. In the 2010s, opioids became a serious problem outside the U.S., mostly among young adults. According to an epidemiologist at Columbia University: "Once pharmaceuticals start targeting other countries and make people feel like opioids are safe, we might see a spike [in opioid abuse]. It worked here. Why wouldn't it work elsewhere?"

Many deaths worldwide from opioids and prescription drugs are from sexually transmitted infections passed through shared needles. This has led to a global initiative of needle exchange programs and research into the varying needle types carrying STIs. Some worry that the epidemic could become a worldwide pandemic if not curtailed. In 2017, prescription drug abuse among teenagers in Canada, Australia, and Europe was comparable to U.S. teenagers.

In 2017, in Lebanon and Saudi Arabia, and in parts of China, surveys found that one in ten students had used prescription painkillers for non-medical purposes. Similar high rates of non-medical use were found among the young throughout Europe, including Spain and the United Kingdom. In 2017, 1,049 people had a death related to opioids in Spain.

While strong opiates are heavily regulated within the European Union, there is a "hidden addiction" with codeine. Codeine, though a mild painkiller, is converted into morphine in the liver. "It's a hidden addiction,' said Dr Michael Bergin of Waterford Institute of Technology, Ireland. 'Codeine abuse affects people with diverse profiles, from children to older people across all social classes."

Asia

Myanmar

In May 2020, Myanmar and the U.N. Office of Drugs and Crime (UNODC) announced that, over the previous three months, police had confiscated illicit drugs with a street value estimated at hundreds of millions of dollars. Most was methamphetamine. They also seized 3,750 liters (990 US gallons) of the potent opiate liquid methylfentanyl.

Iran

Main article: Opium in Iran

In 2022, Iran had the highest rate of nonmedical opium use in the world. Proximity to opiates produced in Afghanistan and Pakistan make Iranian society vulnerable to opiate addiction.

Europe

In 2017, in Europe, prescription opioids accounted for three‐quarter of overdose deaths, which represented 3.5% of total deaths among 15-39-year-olds. While deaths from overdoses related to illicit fentanyl and oxycodone are relatively rare in the UK and Europe, fatal outcomes from opioid intoxications have seen a moderate increase since 2015. In continental Europe, the rise of deaths as a result of opioid/opiate use had been partly due to chronic illnesses of addicts 40 years and older, but some of the recent deaths were experienced by younger users experimenting with 'designer drugs'. Generally speaking, the use of fentanyl by addicts in Europe has been rare as of 2022, but at the same time general deaths from opioid use have increased by 177% since 2019. As in other parts of the Western world, the COVID-19 pandemic has brought a reduced availability of therapies for addicts, but at the same time increased the availability of synthetic opioids on the black market.

United Kingdom

From January to August 2017, there were 60 fatal overdoses of fentanyl in the UK. In England, opioid prescribing in general practice mirrors general geographical health inequalities. In July 2019, two Surrey GPs working for a Farnham-based online pharmacy were suspended by the General Medical Council for prescribing opioids online without appropriate safeguards. Public Health England reported in September 2019 that half the patients using strong painkillers, antidepressants and sleeping tablets had been on them for more than a year, which was generally longer than was "clinically" appropriate and where the risks could outweigh the benefits. They found that problems in the UK were less than in most comparable countries, but there were 4,359 deaths related to drug poisoning, largely opioids, in England and Wales in 2018 – the highest number recorded since 1993.

Public Health England reported in September 2019 that 11.5 million adults in England had been prescribed benzodiazepines, Z-drugs, gabapentinoids, opioids, or antidepressants in the year ending March 2018. Half of these had been prescribed for at least a year. About 540,000 had been prescribed opioids continuously for three years or more. Prescribing of opioids and Z-drugs had decreased, but antidepressants and gabapentinoids had increased, gabapentinoids by 19% between 2015 and 2018 to around 1.5 million.

It was reported that in 2021/2022, 1.80 million patients were prescribed dependency-forming medicines in the most deprived areas in England, 1.66 times more than the number prescribed these medicines in the least deprived areas. This pattern had been consistent since 2015/2016.

France

A study of prescription opioid use in France over 2004-2017  found that the use of strong prescription opioids more than doubled over the period. There was a large increase in the use of oxycodone for chronic non-cancer pain, by nearly 20-fold. Prescription opioid-related hospitalizations increased from 15 to 40 per 1,000,000 population (+167%, 2000–2017). Heroin and methadone hospitalisations were much lower, increasing from 2.6 to 6.9 per 100,000, with all of the increase due to methadone use rather than heroin. Opioid-related deaths, including drugs of abuse, rose from 1.3 to 3.2 per 1,000,000 population (+146%, 2000–2015).

Africa

West Africa

Further information: Opioid addiction in West Africa

There were 4 million opioid addicts in Nigeria in 2025, driven by unlicensed, highly addictive opioids illegally exported from India. A 2024 BBC investigation exposed Aveo Pharmaceuticals, a Mumbai-based company, as a key supplier of Tafrodol and similar pills, which contain tapentadol, a potent opioid, and carisoprodol, a highly addictive muscle relaxant banned in Europe. This combination has led to severe addiction, overdoses, and painful withdrawal symptoms.

The rise of these opioids followed tramadol restrictions in Nigeria and India, creating a demand for new alternatives. These combination pills are now cheap and widely available on the streets of Ghana, Nigeria, and Ivory Coast, devastating the lives of millions of young people and prompting local leaders to form vigilante groups to seize and destroy the drugs.

Accessibility of prescribed opioids

The worry surrounding the potential of a worldwide pandemic has affected opioid accessibility in countries around the world. Approximately 25.5 million people per year, including 2.5 million children, die without pain relief worldwide, with many of these cases occurring in low and middle-income countries. The current disparity in accessibility to pain relief in various countries is significant. The U.S. produces or imports 30 times as much pain relief medication as it needs, while low-income countries such as Nigeria receive less than 0.2% of what they need. 90% of all the morphine in the world is used by the world's richest 10%.

America's opioid epidemic has resulted in an "opiophobia" that is stirring conversations among some Western legislators and philanthropists about adopting a "war on drugs rhetoric" to oppose the idea of increasing opioid accessibility in other countries, in fear of starting similar opioid epidemics abroad. The International Narcotics Control Board (INCB), a monitoring agency established by the U.N. to prevent addiction and ensure appropriate opioid availability for medical use, has written model laws limiting opioid accessibility that it encourages countries to enact. Many of these laws more significantly impact low-income countries; for instance, one model law ruled that only doctors could supply opioids, which limited opioid accessibility in poorer countries that had a scarce number of doctors.

In 2018, deputy head of China's National Narcotics Commission Liu Yuejin criticized the U.S. market's role in driving opioid demand.

In 2016, it was reported that while Mexican cartels are the main source of heroin smuggled into the U.S., Chinese suppliers provide both raw fentanyl and the machinery necessary for its production. In 2016 in British Columbia, police discovered a lab making 100,000 fentanyl pills each month, which they were shipping to Calgary, Alberta. 90 people in Calgary overdosed on the drug in 2015. In 2016 in Southern California, a home-operated drug lab with six pill presses was uncovered by federal agents. Each machine was capable of producing thousands of pills an hour.

In 2018, a woman died in London after getting a prescription for tramadol from an online doctor based in Prague who had not considered her medical history. Regulators in the UK admitted that there was nothing they could do to stop this from happening again. A reporter from The Times was able to buy opioids from five online pharmacies in September 2019 without any contact with their GP by filling in an online questionnaire and sending a photocopy of their passport.

Alternative for opioids

Alternative drug options for opioids include over the counter pain medication such as Ibuprofen, Tylenol (acetaminophen/paracetamol), and Aspirin or steroid options. A German study comparing legal opioid use between different countries concluded that a high consumption of oxycodone could be attributed to the non-availability of the drug metamizole, a non-opioid pain reliever which is heavily used in some countries such as Germany and Austria, but which is banned in others such as the US and Canada.

Along with drug alternatives, many other alternatives can provide relief through physical activities. Physical therapy, acupuncture, injections/nerve blocks, massages, and relaxation techniques are physical activities that have been found to help with chronic pain. New pain management drugs like cannabis and cannabinoids have also been found to help treat symptoms of pain. Many treatments like cancer treatments are using these drugs to help manage pain.

Signs of addiction

People that are addicted to opioids can have many changes in behavior. Some of the common signs or symptoms of addiction include spending more time alone, losing interest in activities, quickly changing moods, sleeping at odd hours, getting in trouble with the law, and financial hardships. People that notice any of these behaviors in a peer or in oneself, are usually advised to consult a physician.

Treatment and prevention of addiction

Opioid use disorder can be treated in a number of different ways: Medication assisted treatment pathways offer methadone, Suboxone (Buprenorphine/naloxone) and Vivitrol (naltrexone), though naltrexone has poor treatment outcomes due to low patient retention. According to the 2017 Surgeon General's report, medication (buprenorphine/methadone) assisted therapies (MAT's) remain the gold standard in evidence-based care for opiate addiction, with the highest reduction in morbidity, mortality, and general negative outcomes achieved through long term opioid replacement therapy. The report makes recommendations concerning expanding access to MAT in order to combat the opioid epidemic. Social stigma regarding medication-assisted treatment in nations like the USA have been a major barrier in implementing evidence based treatments for opiate addiction.

Cognitive behavioral therapies and counseling are proven effective (though less efficacious on their own than medication assisted therapies) as well as digital care programs to increase abstinence rates.

A number of methods for the prevention of opioid addiction have been used and suggested. One method is the creation of anti-opioid advertisements. In the 1990s, advertisements depicting drug-seeking people purposefully slamming their arms into doors and crashing their cars, were unsuccessfully targeted at teens. These ads were unsuccessful because they emphasized the risk of danger, pain, and death caused by opioids. While this tactic would make adults acknowledge the risks and stop using opioids, for many teenagers, the perceived danger adds to the appeal, as smoking becomes a form of rebellion against authoritative adults. When ads were created that instead channeled teenage rebellion toward resisting the tobacco industry's manipulative tactics, the numbers of teens smoking went down. The makers of these ads feel that since the internet allows teenagers to view gruesome things anyway, it is perfectly acceptable to subject them to images of self-mutilation in order to protect their lives. It is felt that thirty seconds of gruesomeness is a small price to pay for sparing a lifetime (however short) of opioid abuse and its accompanying poverty and crime. These advertisements, which started in the 1980s, are continuing to play on television today, utilizing donated advertisement time. The goals of the most recent advertisements are to show teenagers that addiction can begin after only five days, and that feeding this addiction can consume a person's entire life.

Crack cocaine

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Crack_cocaine

Two grams of crack cocaine

Crack cocaine is a potent, smokable form of the stimulant drug cocaine, chemically known as freebase cocaine. It is produced by processing powdered cocaine with sodium bicarbonate (baking soda) and water, resulting in solid, crystalline "rocks" that can be vaporized and inhaled. This method of consumption leads to rapid absorption into the bloodstream, producing an intense euphoria that peaks within minutes but is short-lived, often leading to repeated use.

First emerging in U.S. urban centers such as New York City, Philadelphia, and Los Angeles in the mid-1980s, crack cocaine became widely available and contributed to a significant public health crisis known as the "crack epidemic". The drug's affordability and potent effects led to widespread addiction, particularly in economically disadvantaged communities. In response, the U.S. government enacted stringent drug laws, including the Anti-Drug Abuse Act of 1986, which imposed severe penalties for crack cocaine offenses. These laws disproportionately affected African American communities, leading to calls for reform and the eventual passage of the Fair Sentencing Act of 2010, which reduced sentencing disparities between crack and powder cocaine offenses.

Crack cocaine use is associated with a range of adverse health effects, including cardiovascular issues, neurological damage, and psychological disorders such as paranoia and aggression. The drug's addictive nature poses significant challenges for treatment and recovery, with many users requiring comprehensive medical and psychological support.

Terminology

The origin of the name "crack" comes from the "crackling" sound (and hence the onomatopoeic moniker "crack") that is produced when the cocaine and its impurities (i.e. water, sodium bicarbonate) are heated past the point of vaporization.

It is also commonly called "rock" on the street, a name that comes from its physical appearance after processing. When bulk quantities of powdered cocaine are mixed with baking soda or ammonia and water, then heated, it forms small, hard, solid crystals or pellets that resemble rocks.

Contraindications

Pregnancy

Crack baby is a term for a child born to a mother who used crack cocaine during her pregnancy. The threat that cocaine use during pregnancy poses to the fetus is now considered exaggerated. Studies show that prenatal cocaine exposure (independent of other effects such as, for example, alcohol, tobacco, or physical environment) has no appreciable effect on childhood growth and development. In 2007, the National Institute on Drug Abuse of the United States warned about health risks while cautioning against stereotyping:

Many recall that "crack babies", or babies born to mothers who used crack cocaine while pregnant, were at one time written off by many as a lost generation. They were predicted to suffer from severe, irreversible damage, including reduced intelligence and social skills. It was later found that this was a gross exaggeration. However, the fact that most of these children appear normal should not be over-interpreted as indicating that there is no cause for concern. Using sophisticated technologies, scientists are now finding that exposure to cocaine during fetal development may lead to subtle, yet significant, later deficits in some children, including deficits in some aspects of cognitive performance, information-processing, and attention to tasks—abilities that are important for success in school.

Chemistry

Main article: Freebase (chemistry)

As the name implies, "freebase" is the base form of cocaine, as opposed to the salt form. It is practically insoluble in water whereas hydrochloride salt is water-soluble.

Smoking freebase cocaine has the additional effect of releasing methylecgonidine into the user's system due to the pyrolysis of the substance (a side effect which insufflating or injecting powder cocaine does not create). Some research suggests that smoking freebase cocaine can be even more cardiotoxic than other routes of administration because of methylecgonidine's effects on lung tissue and liver tissue.

Pure cocaine is prepared by neutralizing its compounding salt with an alkaline solution, which will precipitate non-polar basic cocaine. It is further refined through aqueous-solvent liquid–liquid extraction.

Purer forms of crack resemble off-white, jagged-edged "rocks" of a hard, brittle plastic, with a slightly higher density than candle wax. Like cocaine in other forms, crack rock acts as a local anesthetic, numbing the tongue or mouth only where directly placed. Purer forms of crack will sink in water and melt at the edges when near a flame (crack vaporizes at 90 °C, 194 °F).

Crack cocaine sold on the streets may be adulterated (or "cut") with other substances mimicking the appearance of crack to increase bulk. Use of toxic adulterants such as levamisole, a drug used to treat parasitic worm infections, has been documented.

Synthesis

For cocaine (in plastic bag at bottom) to be converted to crack, supplies are needed: baking soda, a commonly used base in making crack, metal spoon, tealight, and cigarette lighter. The spoon is held over the heat source to "cook" the cocaine into crack.

Sodium bicarbonate (NaHCO₃, common baking soda) is a base used in the preparation of crack, although other weak bases may substitute for it.

The net reaction when using sodium bicarbonate is

Coc-H⁺Cl⁻ + NaHCO₃ → Coc + H₂O + CO₂ + NaCl

With ammonium bicarbonate:

Coc-H⁺Cl⁻ + NH₄HCO₃ → Coc + NH₄Cl + CO₂ + H₂O

With ammonium carbonate:

2(Coc-H⁺Cl⁻) + (NH₄)₂CO₃ → 2 Coc + 2 NH₄Cl + CO₂ + H₂O

Crack cocaine is frequently purchased already in rock form, although it is not uncommon for some users to "wash up" or "cook" powder cocaine into crack themselves. This process is frequently done with baking soda (sodium bicarbonate), water, and a spoon. Once mixed and heated, the bicarbonate reacts with the hydrochloride of the powder cocaine, forming free base cocaine and carbonic acid (H₂CO₃) in a reversible acid-base reaction. The heating accelerates the degradation of carbonic acid into carbon dioxide (CO₂) and water. Loss of CO₂ prevents the reaction from reversing back to cocaine hydrochloride. Free base cocaine separates as an oily layer, floating on the top of the now leftover aqueous phase. It is at this point that the oil is picked up rapidly, usually with a pin or long thin object. This pulls the oil up and spins it, allowing air to set and dry the oil, and allows the maker to roll the oil into the rock-like shape.

The "cooking" process that creates crack

Crack cocaine can also be injected intravenously with the same effect as powder cocaine. However, whereas powder cocaine dissolves in water, crack must be dissolved in an acidic solution such as lemon juice (containing citric acid) or white vinegar (containing acetic acid), a process that effectively reverses the original conversion of powder cocaine to crack. Harm reduction and public health agencies may distribute packets of citric acid or ascorbic acid (vitamin C) for this purpose.

Recreational use

Effects of crack cocaine include euphoria, supreme confidence, loss of appetite, insomnia, alertness, increased energy, a craving for more cocaine, and paranoia (ending after use).

Its initial effect is to release a large amount of dopamine, a brain chemical inducing feelings of euphoria. The high usually lasts from five to ten minutes, after which time dopamine levels in the brain plummet, leaving the user feeling depressed and low. When (powder) cocaine is dissolved and injected, the absorption into the bloodstream is at least as rapid as the absorption of the drug which occurs when crack cocaine is smoked, and similar euphoria may be experienced.

In a 2000 Brookhaven National Laboratory medical department study, based on self-reports of 32 people who used cocaine who participated in the study, "peak high" was found at a mean of 1.4 ± 0.5 minutes.

The onset of cocaine's euphoric effects is fastest with inhalation, beginning after 3–5 seconds. The drug is then quickly transported to the brain, where it acts on the central nervous system, producing an almost immediate "high" that can be very powerful – this initial crescendo of stimulation known as a rush. This is followed by an equally intense low, leaving the user craving more of the drug. Addiction to crack usually occurs within four to six weeks - much more rapidly than regular cocaine.

Route of administration

A woman smoking crack cocaine from a "love rose" in San Francisco, California, in December 2005

Crack cocaine is usually heated in a drug pipe until sublimation occurs at a relatively low temperature (about 90°C) and the vapor is inhaled. This process is commonly referred to as "freebasing." Although commonly called "smoking," this method actually involves vaporizing the drug rather than burning it. If crack cocaine is burned directly, such as in a regular tobacco pipe, roll-your-own cigarette, or aluminum foil higher temperatures may lead to decomposition of the active compound, reducing its effectiveness. This is why vaporization at lower temperatures, rather than combustion, is the preferred method for administration. While no formal studies have specifically quantified the extent of drug loss during combustion, users commonly choose to vaporize crack cocaine in order to maximize its effects and potentially avoid wasting money. Additionally, vaporizing is generally considered less harsh on the throat and lungs compared to smoking crack through a tobacco pipe, as combustion can produce more irritating and toxic by-products.

Pyrolysis products of cocaine that occur only when heated/smoked have been shown to change the effect profile, i.e. anhydroecgonine methyl ester, when co-administered with cocaine, increases the dopamine in CPu and NAc brain regions, and has M₁ — and M₃ — receptor affinity.

The effects felt almost immediately after inhaled are very intense and do not last long — usually 2 to 10 minutes. When smoked, cocaine is sometimes combined with other drugs, such as cannabis, often rolled into a joint or blunt.

Love rose

See also: Drug pipe

A love rose being used to smoke crack cocaine

People often freebase crack with a pipe made from a small glass tube, often taken from "love roses", small glass tubes with a paper rose that are promoted as romantic gifts. These are sometimes called "stems", "horns", "blasters" and "straight shooters". A small piece of clean heavy copper or occasionally stainless steel scouring pad – often called a "brillo" (actual Brillo Pads contain soap, and are not used) or "chore" (named for Chore Boy brand copper scouring pads) – serves as a reduction base and flow modulator in which the "rock" can be melted and boiled to vapor. Crack is smoked by placing it at the end of the pipe; a flame held close to it produces vapor, which is then inhaled by the smoker.

Adverse effects

See also: Chasing the dragon

Physiological

Main physiological effects of crack cocaine

Incidental exposure of the eye to sublimated cocaine while smoking crack cocaine can cause serious injury to the cornea and long-term loss of visual acuity.

The short-term physiological effects of cocaine include constricted blood vessels, dilated pupils, and increased temperature, heart rate, and blood pressure. Some users of cocaine report feelings of restlessness, irritability, and anxiety. In rare instances, sudden death can occur on the first use of cocaine or unexpectedly thereafter. Cocaine-related deaths are often a result of cardiac arrest or seizures followed by respiratory arrest.

Like other forms of cocaine, smoking crack can increase heart rate and blood pressure, leading to long-term cardiovascular problems. Some research suggests that smoking crack or free base cocaine has additional health risks compared to other methods of taking cocaine. Many of these issues relate specifically to the release of methylecgonidine and its effect on the heart, lungs, and liver.

• Toxic adulterants: Many substances may have been added to expand the weight and volume of a batch, while still appearing to be pure crack. Occasionally, highly toxic substances are used, with a range of corresponding short and long-term health risks. Adulterants used with crack and cocaine include milk powder, sugars such as glucose, starch, caffeine, lidocaine, benzocaine, paracetamol, amphetamine, scopolamine and strychnine.
• Smoking problems: Any route of administration poses its own set of health risks; in the case of crack cocaine, smoking tends to be more harmful than other routes. Crack users tend to smoke the drug because that has a higher bioavailability than other routes typically used for drugs of abuse, such as insufflation. Crack has a melting point of around 90 °C (194 °F), and the smoke does not remain potent for long. Therefore, crack pipes are generally very short, to minimize the time between evaporating and ingestion (thereby minimizing loss of potency). Having a very hot pipe pressed against the lips often causes cracked and blistered lips, colloquially known as "crack lip". The use of "convenience store crack pipes"—glass tubes which originally contained small artificial roses—may contribute to this condition. These 4-inch (10-cm) pipes are not durable and will quickly develop breaks; users may continue to use the pipe even though it has been broken to a shorter length. The hot pipe might burn the lips, tongue, or fingers, especially when passed between people who take hits in rapid succession, causing the short pipe to reach higher temperatures than if used by one person alone.
• Pure or large doses: Because the quality of crack can vary greatly, some people might smoke larger amounts of diluted crack, unaware that a similar amount of a new batch of purer crack could cause an overdose. This can trigger heart problems or cause unconsciousness.
• Pathogens on pipes: When pipes are shared, bacteria or viruses can be transferred from person to person.

Crack cocaine causes DNA damage in multiple organs of rats and mice.

Crack lung

In crack users, acute respiratory symptoms have been reported, sometimes termed "crack lung". Symptoms include fever, coughing up blood and difficulty breathing. In the 48-hour period after use, people with these symptoms have also had associated radiographic findings on chest X-ray of fluid in the lungs (pulmonary edema), interstitial pneumonia, diffuse alveolar hemorrhage, and eosinophil infiltration.

Physical side effects from chronic smoking of cocaine include coughing up blood, bronchospasm, itching, fever, diffuse alveolar infiltrates without effusions, pulmonary and systemic eosinophilia, chest pain, lung trauma, sore throat, asthma, hoarse voice, dyspnea (shortness of breath), and an aching, flu-like syndrome.

Crack cocaine users sometimes smoke "fry," which refers to cigarettes or marijuana sticks that have been dipped in embalming fluid and laced with PCP. Formaldehyde and methyl alcohol are the main ingredients found in fry, and their use has been linked to a range of physical health problems, including bronchitis, destruction of body tissues, brain and lung damage, impaired coordination, and inflammation or sores in the throat, nose, and esophagus.

Psychological

Intranasal cocaine and crack use are both associated with pharmacological violence. Crack-related violence is also systemic, relating to disputes between crack dealers and users.

Stimulant drug abuse (particularly amphetamine and cocaine) can lead to delusional parasitosis (aka Ekbom's Syndrome: a mistaken belief they are infested with parasites). For example, excessive cocaine use can lead to formication, nicknamed "cocaine bugs" or "coke bugs", where the affected people believe they have, or feel, parasites crawling under their skin (similar delusions may also be associated with high fever or in connection with alcohol withdrawal, sometimes accompanied by visual hallucinations of insects—see delirium tremens).

People experiencing these hallucinations might scratch themselves to the extent of serious skin damage and bleeding, especially when they are delirious.

Paranoia and anxiety are among the most common psychological symptoms of crack cocaine use. Psychosis is more closely associated with smoking crack cocaine than intranasal and intravenous use.

Pregnancy and nursing

Main article: Prenatal cocaine exposure

Crack baby is a term for a child born to a mother who used crack cocaine during her pregnancy. The threat that cocaine use during pregnancy poses to the fetus is now considered exaggerated. Studies show that prenatal cocaine exposure (independent of other effects such as, for example, alcohol, tobacco, or physical environment) has no appreciable effect on childhood growth and development. However, the official opinion of the National Institute on Drug Abuse of the United States warns about health risks while cautioning against stereotyping:

Many recall that "crack babies", or babies born to mothers who used crack cocaine while pregnant, were at one time written off by many as a lost generation. They were predicted to suffer from severe, irreversible damage, including reduced intelligence and social skills. It was later found that this was a gross exaggeration. However, the fact that most of these children appear normal should not be over-interpreted as indicating that there is no cause for concern. Using sophisticated technologies, scientists are now finding that exposure to cocaine during fetal development may lead to subtle, yet significant, later deficits in some children, including deficits in some aspects of cognitive performance, information-processing, and attention to tasks—abilities that are important for success in school.

There are also warnings about the threat of breastfeeding: The March of Dimes said "it is likely that cocaine will reach the baby through breast milk," and advises the following regarding cocaine use during pregnancy:

Cocaine use during pregnancy can affect a pregnant woman and her unborn baby in many ways. During the early months of pregnancy, it may increase the risk of miscarriage. Later in pregnancy, it can trigger preterm labor (labor that occurs before 37 weeks of pregnancy) or cause the baby to grow poorly. As a result, cocaine-exposed babies are more likely than unexposed babies to be born with low birth weight (less than 5.5 lb or 2.5 kg). Low-birthweight babies are 20 times more likely to die in their first month of life than normal-weight babies, and face an increased risk of lifelong disabilities such as mental retardation and cerebral palsy. Cocaine-exposed babies also tend to have smaller heads, which generally reflect smaller brains. Some studies suggest that cocaine-exposed babies are at increased risk of birth defects, including urinary tract defects and, possibly, heart defects. Cocaine also may cause an unborn baby to have a stroke, irreversible brain damage, or a heart attack.

Reinforcement disorders

Tolerance

An appreciable tolerance to cocaine's high may develop, with many addicts reporting that they seek but fail to achieve as much pleasure as they did from their first experience. Some users will frequently increase their doses to intensify and prolong the euphoric effects. While tolerance to the high can occur, users might also become more sensitive (drug sensitization) to cocaine's local anesthetic (painkilling) and convulsant (seizure-inducing) effects, without increasing the dose taken; this increased sensitivity may explain some deaths occurring after apparent low doses of cocaine.

Addiction

Main article: Substance dependence

Roxanne, Dave and Michelle were quietly sitting in an alley and smoking crack cocaine. They agreed to pose for a quick informal shapshot. All were warm, friendly, and good-natured. In the DTES of Vancouver BC Canada.

Crack cocaine is popularly thought to be the most addictive form of cocaine. However, this claim has been contested: Morgan and Zimmer wrote that available data indicated that "smoking cocaine by itself does not increase markedly the likelihood of dependence ... The claim that cocaine is much more addictive when smoked must be reexamined." They argued that cocaine users who are already prone to abuse are most likely to "move toward a more efficient mode of ingestion" (that is, smoking).

The intense desire to recapture the initial high is what is so addictive for many users. On the other hand, Reinarman et al. wrote that the nature of crack addiction depends on the social context in which it is used and the psychological characteristics of users, pointing out that many heavy crack users can go for days or weeks without using the drug.

Overdose

A typical response among users is to have another hit of the drug; however, the levels of dopamine in the brain take a long time to replenish themselves, and each hit taken in rapid succession leads to progressively less intense highs. Nonetheless, a person might binge for 3 or more days without sleep, while inhaling hits from a pipe.

Use of cocaine in a binge, during which the drug is taken repeatedly and at increasingly high doses, leads to a state of increasing irritability, restlessness, and paranoia. This may result in total paranoid psychosis, in which the individual loses touch with reality and experiences auditory hallucinations.

Large amounts of crack cocaine (several hundred milligrams or more) intensify the user's high, but may also lead to bizarre, erratic, and violent behavior. Large amounts can induce tremors, vertigo, muscle twitches, paranoia, or, with repeated doses, a toxic reaction closely resembling amphetamine poisoning.

Society and culture

Synonyms

Crack cocaine is known by many streets names, the most common of which include, base; boulder; gravel; hail; hubba; rock; and yahoo.

Drug combinations

Crack cocaine may be combined with amphetamine ("croak"); tobacco ("coolie"); marijuana ("turbbo"); heroin ("moon rock"); and phencyclidine ("spacebase"). This type of mixed-drug use is higher risk than single-drug use.

Consumption

Further information: Crack pipe (smoking utensil)

Crack smoking is commonly performed with utensils such as pipes ; improvised pipes made from a plastic bottle; water pipes; and laboratory pipettes.

Legal status

US Food and Drug Administration anti-crack poster distributed in the 1980s

Cocaine is listed as a Schedule I drug in the United Nations 1961 Single Convention on Narcotic Drugs, making it illegal for non-state-sanctioned production, manufacture, export, import, distribution, trade, use and possession. In most states (except in the United States) crack falls under the same category as cocaine.

Australia

In Australia, crack falls under the same category as cocaine, which is listed as a Schedule 8 controlled drug, indicating that any substances and preparations for therapeutic use under this category have a high potential for abuse and addiction. It is permitted for some medical use but is otherwise outlawed.

Canada

As a Schedule I substance under the Controlled Drugs and Substances Act, crack is not differentiated from cocaine and other coca products. However, the court may weigh the socio-economic factors of crack usage in sentencing. As a guideline, Schedule I drugs carry a maximum seven-year prison sentence for possession for an indictable offense and up to life imprisonment for trafficking and production. A summary conviction on possession carries a $1000–2000 fine and/or six months to a year imprisonment.

United States

In the United States, cocaine is a Schedule II drug under the Controlled Substances Act, indicating that it has a high abuse potential but also carries a medicinal purpose. Under the Controlled Substances Act, crack and cocaine are considered the same drug.

The Anti-Drug Abuse Act of 1986 increased penalties for crack cocaine possession and usage. It mandated a mandatory minimum sentence of five years without parole for possession of five grams of crack; to receive the same sentence with powder cocaine one had to have 500 grams. This sentencing disparity was reduced from 100-to-1 to 18-to-1 by the Fair Sentencing Act of 2010.

Europe

In the United Kingdom, crack is a Class A drug under the Misuse of Drugs Act 1971. In the Netherlands it is a List 1 drug of the Opium Law.

Political scandals

D.C. Mayor Marion Barry captured on a surveillance camera smoking crack cocaine during a sting operation

Marion Barry, Mayor of Washington D.C., was filmed smoking crack in 1990 in a sting operation.^[57] Rob Ford, Mayor of Toronto, Ontario was filmed smoking crack in 2013 by gang members while holding office.

Impact

Tire repair shop, New Orleans. Sign prohibits loitering, selling of crack cocaine, and "cat selling", a euphemism for prostitution. "NOPD will be called" refers to New Orleans Police.

Many major American urban areas contain crack houses. In some cases, enraged citizens have burned crack houses to the ground, in hopes that by destroying the sites for drug operations they would also drive the illegal industries from their neighborhoods.

Crack cocaine use is often initiated through close social relationships and may serve as a coping mechanism for trauma and negative emotions. It is perceived as more potent and harmful than powdered cocaine, with increased risks of violence, social isolation, and involvement in the sex trade. Based on a small sample of women, findings suggest the importance of addressing emotional regulation, trauma, and social support in prevention and treatment, though they are not broadly generalizable.

Energy conversion efficiency

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Energy_conversion_efficiency 

Useful output energy is always lower than input energy.

Efficiency of power plants, world total, 2008

Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical, electric power, mechanical work, light (radiation), or heat. The resulting value, η (eta), ranges between 0 and 1.

Overview

Energy conversion efficiency depends on the usefulness of the output. All or part of the heat produced from burning a fuel may become rejected waste heat if, for example, work is the desired output from a thermodynamic cycle. Energy converter is an example of an energy transformation. For example, a light bulb falls into the categories energy converter. ${\displaystyle \eta =\frac{P_{\mathrm{o}\mathrm{u}\mathrm{t}}}{P_{\mathrm{i}\mathrm{n}}}}$ Even though the definition includes the notion of usefulness, efficiency is considered a technical or physical term. Goal or mission oriented terms include effectiveness and efficacy.

Generally, energy conversion efficiency is a dimensionless number between 0 and 1.0, or 0% to 100%. Efficiencies cannot exceed 100%, which would result in a perpetual motion machine, which is impossible.

However, other effectiveness measures that can exceed 1.0 are used for refrigerators, heat pumps and other devices that move heat rather than convert it. It is not called efficiency, but the coefficient of performance, or COP. It is a ratio of useful heating or cooling provided relative to the work (energy) required. Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs. The COP usually exceeds 1, especially in heat pumps, because instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required. Most air conditioners have a COP of 2.3 to 3.5.

When talking about the efficiency of heat engines and power stations the convention should be stated, i.e., HHV (a.k.a. Gross Heating Value, etc.) or LCV (a.k.a. Net Heating value), and whether gross output (at the generator terminals) or net output (at the power station fence) are being considered. The two are separate but both must be stated. Failure to do so causes endless confusion.

Related, more specific terms include

• Electrical efficiency, useful power output per electrical power consumed;
• Mechanical efficiency, where one form of mechanical energy (e.g. potential energy of water) is converted to mechanical energy (work);
• Thermal efficiency or Fuel efficiency, useful heat and/or work output per input energy such as the fuel consumed;
• 'Total efficiency', e.g., for cogeneration, useful electric power and heat output per fuel energy consumed. Same as the thermal efficiency.
• Luminous efficiency, that portion of the emitted electromagnetic radiation is usable for human vision.

Chemical conversion efficiency

The change of Gibbs energy of a defined chemical transformation at a particular temperature is the minimum theoretical quantity of energy required to make that change occur (if the change in Gibbs energy between reactants and products is positive) or the maximum theoretical energy that might be obtained from that change (if the change in Gibbs energy between reactants and products is negative). The energy efficiency of a process involving chemical change may be expressed relative to these theoretical minima or maxima. The difference between the change of enthalpy and the change of Gibbs energy of a chemical transformation at a particular temperature indicates the heat input required or the heat removal (cooling) required to maintain that temperature.

A fuel cell may be considered to be the reverse of electrolysis. For example, an ideal fuel cell operating at a temperature of 25 °C having gaseous hydrogen and gaseous oxygen as inputs and liquid water as the output could produce a theoretical maximum amount of electrical energy of 237.129 kJ (0.06587 kWh) per gram mol (18.0154 gram) of water produced and would require 48.701 kJ (0.01353 kWh) per gram mol of water produced of heat energy to be removed from the cell to maintain that temperature.

An ideal electrolysis unit operating at a temperature of 25 °C having liquid water as the input and gaseous hydrogen and gaseous oxygen as products would require a theoretical minimum input of electrical energy of 237.129 kJ (0.06587 kWh) per gram mol (18.0154 gram) of water consumed and would require 48.701 kJ (0.01353 kWh) per gram mol of water consumed of heat energy to be added to the unit to maintain that temperature. It would operate at a cell voltage of 1.24 V.

For a water electrolysis unit operating at a constant temperature of 25 °C without the input of any additional heat energy, electrical energy would have to be supplied at a rate equivalent of the enthalpy (heat) of reaction or 285.830 kJ (0.07940 kWh) per gram mol of water consumed. It would operate at a cell voltage of 1.48 V. The electrical energy input of this cell is 1.20 times greater than the theoretical minimum so the energy efficiency is 0.83 compared to the ideal cell. 

A water electrolysis unit operating with a higher voltage that 1.48 V and at a temperature of 25 °C would have to have heat energy removed in order to maintain a constant temperature and the energy efficiency would be less than 0.83.

The large entropy difference between liquid water and gaseous hydrogen plus gaseous oxygen accounts for the significant difference between the Gibbs energy of reaction and the enthalpy (heat) of reaction.

Fuel heating values and efficiency

In Europe the usable energy content of a fuel is typically calculated using the lower heating value (LHV) of that fuel, the definition of which assumes that the water vapor produced during fuel combustion (oxidation) remains gaseous, and is not condensed to liquid water so the latent heat of vaporization of that water is not usable. Using the LHV, a condensing boiler can achieve a "heating efficiency" in excess of 100% (this does not violate the first law of thermodynamics as long as the LHV convention is understood, but does cause confusion). This is because the apparatus recovers part of the heat of vaporization, which is not included in the definition of the lower heating value of a fuel. In the U.S. and elsewhere, the higher heating value (HHV) is used, which includes the latent heat for condensing the water vapor, and thus the thermodynamic maximum of 100% efficiency cannot be exceeded.

Wall-plug efficiency, luminous efficiency, and efficacy

The absolute irradiance of four different gases when used in a flashtube. Xenon is by far the most efficient of the gases, although krypton is more effective at a specific wavelength of light.

The sensitivity of the human eye to various wavelengths. Assuming each wavelength equals 1 watt of radiant energy, only the center wavelength is perceived as 683 candelas (1 watt of luminous energy), equaling 683 lumens. The vertical colored-lines represent the 589 (yellow) sodium line, and popular 532 nm (green), 671 nm (red), 473 nm (blue), and 405 nm (violet) laser pointers.

A Sankey diagram showing the multiple stages of energy loss between the wall plug and the light output of a fluorescent lamp. The greatest losses occur due to the Stokes shift.

In optical systems such as lighting and lasers, the energy conversion efficiency is often referred to as wall-plug efficiency. The wall-plug efficiency is the measure of output radiative-energy, in watts (joules per second), per total input electrical energy in watts. The output energy is usually measured in terms of absolute irradiance and the wall-plug efficiency is given as a percentage of the total input energy, with the inverse percentage representing the losses.

The wall-plug efficiency differs from the luminous efficiency in that wall-plug efficiency describes the direct output/input conversion of energy (the amount of work that can be performed) whereas luminous efficiency takes into account the human eye's varying sensitivity to different wavelengths (how well it can illuminate a space). Instead of using watts, the power of a light source to produce wavelengths proportional to human perception is measured in lumens. The human eye is most sensitive to wavelengths of 555 nanometers (greenish-yellow) but the sensitivity decreases dramatically to either side of this wavelength, following a Gaussian power-curve and dropping to zero sensitivity at the red and violet ends of the spectrum. Due to this the eye does not usually see all of the wavelengths emitted by a particular light-source, nor does it see all of the wavelengths within the visual spectrum equally. Yellow and green, for example, make up more than 50% of what the eye perceives as being white, even though in terms of radiant energy white-light is made from equal portions of all colors (i.e.: a 5 mW green laser appears brighter than a 5 mW red laser, yet the red laser stands-out better against a white background). Therefore, the radiant intensity of a light source may be much greater than its luminous intensity, meaning that the source emits more energy than the eye can use. Likewise, the lamp's wall-plug efficiency is usually greater than its luminous efficiency. The effectiveness of a light source to convert electrical energy into wavelengths of visible light, in proportion to the sensitivity of the human eye, is referred to as luminous efficacy, which is measured in units of lumens per watt (lm/w) of electrical input-energy.

Unlike efficacy (effectiveness), which is a unit of measurement, efficiency is a unitless number expressed as a percentage, requiring only that the input and output units be of the same type. The luminous efficiency of a light source is thus the percentage of luminous efficacy per theoretical maximum efficacy at a specific wavelength. The amount of energy carried by a photon of light is determined by its wavelength. In lumens, this energy is offset by the eye's sensitivity to the selected wavelengths. For example, a green laser pointer can have greater than 30 times the apparent brightness of a red pointer of the same power output. At 555 nm in wavelength, 1 watt of radiant energy is equivalent to 683 lumens, thus a monochromatic light source at this wavelength, with a luminous efficacy of 683 lm/w, would have a luminous efficiency of 100%. The theoretical-maximum efficacy lowers for wavelengths at either side of 555 nm. For example, low-pressure sodium lamps produce monochromatic light at 589 nm with a luminous efficacy of 200 lm/w, which is the highest of any lamp. The theoretical-maximum efficacy at that wavelength is 525 lm/w, so the lamp has a luminous efficiency of 38.1%. Because the lamp is monochromatic, the luminous efficiency nearly matches the wall-plug efficiency of < 40%.

Calculations for luminous efficiency become more complex for lamps that produce white light or a mixture of spectral lines. Fluorescent lamps have higher wall-plug efficiencies than low-pressure sodium lamps, but only have half the luminous efficacy of ~ 100 lm/w, thus the luminous efficiency of fluorescents is lower than sodium lamps. A xenon flashtube has a typical wall-plug efficiency of 50–70%, exceeding that of most other forms of lighting. Because the flashtube emits large amounts of infrared and ultraviolet radiation, only a portion of the output energy is used by the eye. The luminous efficacy is therefore typically around 50 lm/w. However, not all applications for lighting involve the human eye nor are restricted to visible wavelengths. For laser pumping, the efficacy is not related to the human eye so it is not called "luminous" efficacy, but rather simply "efficacy" as it relates to the absorption lines of the laser medium. Krypton flashtubes are often chosen for pumping Nd:YAG lasers, even though their wall-plug efficiency is typically only ~ 40%. Krypton's spectral lines better match the absorption lines of the neodymium-doped crystal, thus the efficacy of krypton for this purpose is much higher than xenon; able to produce up to twice the laser output for the same electrical input. All of these terms refer to the amount of energy and lumens as they exit the light source, disregarding any losses that might occur within the lighting fixture or subsequent output optics. Luminaire efficiency refers to the total lumen-output from the fixture per the lamp output.

With the exception of a few light sources, such as incandescent light bulbs, most light sources have multiple stages of energy conversion between the "wall plug" (electrical input point, which may include batteries, direct wiring, or other sources) and the final light-output, with each stage producing a loss. Low-pressure sodium lamps initially convert the electrical energy using an electrical ballast, to maintain the proper current and voltage, but some energy is lost in the ballast. Similarly, fluorescent lamps also convert the electricity using a ballast (electronic efficiency). The electricity is then converted into light energy by the electrical arc (electrode efficiency and discharge efficiency). The light is then transferred to a fluorescent coating that only absorbs suitable wavelengths, with some losses of those wavelengths due to reflection off and transmission through the coating (transfer efficiency). The number of photons absorbed by the coating will not match the number then reemitted as fluorescence (quantum efficiency). Finally, due to the phenomenon of the Stokes shift, the re-emitted photons will have a longer wavelength (thus lower energy) than the absorbed photons (fluorescence efficiency). In very similar fashion, lasers also experience many stages of conversion between the wall plug and the output aperture. The terms "wall-plug efficiency" or "energy conversion efficiency" are therefore used to denote the overall efficiency of the energy-conversion device, deducting the losses from each stage, although this may exclude external components needed to operate some devices, such as coolant pumps.