Narcan is an opioid antagonist that can rapidly reverse overdoses

Naltrexone blocks the reward effects of alcohol and opioids

Naltrexone is used to treat alcohol and opioid dependence, blocking opioid receptors in the brain, reducing cravings, and preventing the euphoric effects of alcohol or opioids. It is nonaddictive and works best as part of a comprehensive treatment plan, including counseling or therapy, to support long-term recovery.

Opioids mimic naturally produced endorphins to dull pain.

Fentanyl can be up to 100 times more potent than morphine

A synthetic opioid, fentanyl is highly addictive and incredibly fast-acting—a fatal dose is equal to a few grains of table salt. Once it enters the body, fentanyl floods naturally occurring opioid receptors, which can cause the body to shut down its breathing reflex, leading to a fatal overdose.

Methadone binds to the same receptors as heroin and other opioids

Methadone is a long-acting opioid agonist that works by binding to the same brain receptors as other opioids (like heroin or morphine), but without producing intense euphoria. It reduces withdrawal symptoms and cravings, helping people stabilize and avoid illicit opioid use.

Opioids are a class of drugs including fentanyl, heroin, oxycodone, and more.

Fentanyl is better at crossing the blood-brain barrier than other opioids

Among opioids, fentanyl is uniquely adept at crossing the blood-brain barrier—the brain's security fence against harmful substances. This enables a lightning-fast high. It ends just as quickly, sometimes within minutes (where a heroin high lasts hours), and still results in the same withdrawal symptoms.

Synthetic opioids: a historical and clinical review

In the 19th century, researchers began synthesizing and isolating poppy plant alkaloids, leading to the invention of morphine, codeine, heroin, oxycodone, and others. These highly addictive variants eventually gave rise to illicit use and a widespread underground market, laying the foundation for the current opioid crisis.

Fast, cheap, and deadly: How fentanyl replaced heroin and hooked America

This interactive article details how fentanyl has largely replaced heroin in the drug trade, with fatal results. Fentanyl was first developed in 1959 as an anesthetic for pain relief, but the drug took hold in the US black market in 2014 and has since exploded in the intervening decade.

Why is fentanyl poisoning street drugs?

A few grains of fentanyl, a synthetic opioid far more potent than heroin or morphine, is enough to kill a typical adult human. It's made its way into other, less lethal street drugs, where it may be used to increase the highs experienced by unknowing users, increasing their likelihood of addiction and overdose. This 39-minute podcast episode is the first half of a two-part series exploring fentanyl's rise.

The body produces its own opioids that act on several receptor types throughout the body, triggering the release of dopamine and suppression of noradrenaline, neurotransmitters associated with reward and alertness, respectively.

From prescriptions to street drugs: Opioids trajectory across America

Exclusive data obtained by The Washington Post from the Centers for Disease Control and Prevention shows how individual counties moved through three waves of the opioid crisis, each wave paving the way for the next. Between 2011 and 2017, the drug responsible for the majority of overdose deaths shifted from prescription pills to heroin to fentanyl. Together, oxycodone, hydrocodone, heroin, and fentanyl have been major drivers in declining life expectancy in the US.

Why are drug dealers putting fentanyl in everything?

A few grains of fentanyl, a synthetic opioid far more potent than heroin or morphine, are enough to kill a typical adult human. It's made its way into other, less lethal street drugs, where it may be used to increase the highs experienced by unknowing users, increasing their likelihood of addiction and overdose.

The three waves of the opioid crisis: overprescription, heroin, and fentanyl

The US opioid crisis has unfurled in three distinct waves, each spiraling into an epidemic that's killed millions. The first crested in the 1990s with the overprescription of opioids for pain relief. The second manifested as heroin overdoses in the 2010s. The third began in 2013 with the rise of deaths related to tramadol and fentanyl.

Narcolepsy occurs when the brain loses its ability to control its sleep-wake cycle.

One person dies from opioids every 7 to 8 minutes

This collection of infographics by the National Institute for Health Care Management helps put the crisis into perspective. The opioid epidemic has had three waves. Opioid-related deaths increasingly involve synthetic versions of the drug class, contributing to 83 percent of all opioid-related deaths in 2020. Use these infographics to learn more about the crisis.

The story of Marie Nyswander, the woman who co-discovered methadone maintenance

Methadone, an opioid with distinct effects from heroin, revolutionized heroin addiction in the 1960s. Marie Nyswander was a psychoanalyst who helped discover the treatment process which is still in use today. Here's a podcast episode examining her life and role in the field of addiction treatment.

Overuse of opioids can lead to hypersensitivity to pain.

Why the human brain loves opioids

When opioids enter the brain, they dock in receptors, blocking electrical pulses such as those that communicate pain. They also trigger the release of dopamine, a neurotransmitter tied to motivation and associated with stress relief.

Opium is a milky liquid substance extracted from unripe poppy plant seeds

It's been used for ages to reduce pain and induce euphoria, both of which are side effects of the plant's alkaloids—nitrogen-based compounds with pronounced physical effects. Isolating and synthesizing derivatives of these naturally occurring chemicals enabled the invention of morphine, heroin, and other opioids.

Opioid prescription rates by states and counties

The origins of the US' ongoing opioid crisis are typically traced to the more than 1 billion prescription pain pills that flooded medicine cabinets between 2005 and 2019. This prescription opioid epidemic resulted in more than 210,000 fatal overdoses and set the stage for the ongoing crisis fueled by heroin and fentanyl.

Anesthetics slow brain activity by promoting inhibitory neurotransmitters

Drugs like propofol and isoflurane increase activity at the GABA receptor, which opens chloride channels. These ions enter neurons and hyperpolarize them, making them less likely to fire. Dexmedetomidine instead blocks norepinephrine receptors in the brainstem to sedate patients.

The science of addiction treatment

A helpful resource from the National Institute on Drug Abuse (part of the NIH). This article examines addiction treatment and recovery through the science behind several accepted methods. The guide draws helpful comparisons with other chronic disease treatments. In particular, it discusses the overlap between medications and therapeutic treatments, and the understanding that relapse doesn’t indicate treatment failure—only a need for continued or modified care.

Morphine, heroin, codeine, and more were derived from opium

Opium reached the US at about the time early colonists were itching for ways to soothe aches and pains. The active ingredient in the substance was isolated in the early 19th century, eventually leading to the manufacture and commercial sale of morphine, heroin, and other opium-based drugs.

The Cincinnati Enquirer's Pulitzer-winning look at the opioid epidemic

Synthetic opioids kill someone in the US every 16 minutes. Communities across the country have been ravaged by deaths, overdoses, jail time, and babies born with drug-related medical problems as opioid abuse became a typical feature of many American towns. This seven-part exposé provides an inside look at the effect in southern Ohio and northern Kentucky.

Learn about the US opioid crisis in this free course

Where did the US opioid crisis come from, and how did it spread? Learn this and more in this free, online Harvard University course. Learn about the disease model of addiction treatment and management, and get up-to-date with public health and law enforcement's current harm reduction practices. This free resource gives users a greater understanding of opioid addiction and the epidemic still haunting the US.

See how DOJ prosecutors took down a pharmaceutical company's executives over the opioid crisis

This FRONTLINE documentary follows federal prosecutors as they used anti-racketeering laws to convict executives at Insys Therapeutics, a pharmaceutical company that bribed doctors to overprescribe a fentanyl painkiller.

The National Institute on Drug Abuse's resource library

The National Institute on Drug Abuse website is an in-depth and highly prolific resource on addiction science. Explore the vast scope of this website to access comprehensive guides, data visualizations, and educational materials on all facets of addiction and its treatment.

Postpartum depression typically starts in the weeks following childbirth, and the disorder can keep someone from performing tasks of daily living.

Addictive drugs can cause dopamine levels to become ten times higher than normal.

Drug tolerance and withdrawals are consequences of overloading dopamine circuits

Addictive substances or behaviors will typically flood our brains with more dopamine than usual. In response to the overstimulation, our brains will decrease the number of available dopamine receptors. This results in the need for more stimulus for the same response (tolerance) and a rise in negative feelings when the stimulus is absent (withdrawal).

Opioid epidemic 101: lawsuits and settlements

State and local governments trying to address the opioid epidemic have sued organizations they believe started and supported the crisis. Companies that made, distributed, or contributed to sales of the highly addictive painkillers are expected to pay more than $50B in settlements. These settlements specifically state that at least 85% of settlement funds must be spent on addressing the epidemic, though where exactly the money is going is unclear.

Addiction is defined as chronic compulsive drug use despite adverse consequences

This resource from the National Institute on Drug Abuse provides a comprehensive look at addiction as a complex brain disorder. It explores why people initially take addictive substances and how continued use alters the brain’s reward system.

Drugs 101: An interactive guide

What's the difference between opioids and psychedelics? This guide details specific drugs and their various associated effects. Drugs in this wheel fall into seven categories: stimulants, depressants, empathogens, psychedelics, dissociatives, cannabinoids, and opioids.

Addiction develops when the pleasure circuits in the brain get overwhelmed

Normal pleasure circuits become overwhelmed by addictive substances, triggering dopamine floods many times stronger than those induced by everyday reward experiences. The understanding of addiction as a brain disease has led to treatments pairing medication and counseling.

Nanoplastics can bypass the blood-brain barrier and may harm the nervous system

Nanoplastics are formed from the breakdown of microplastics and can breach cells. Their large surface area relative to size allows them to carry higher concentrations of forever chemicals than the surrounding environment into sensitive organs.

A workplace back injury and the opioid prescription that followed set one Texas father on the path the Washington Post's video profile calls his rise to fentanyl 'kingpin.'

Unlike food allergens, encountering inhaled allergens—like pollen—rarely causes life-threatening illness.

A stand-in 'nose' may help people with anosmia to smell certain odors

In a 2025 paper, researchers reported they'd created a proof-of-concept device that bypasses typical olfactory pathways and instead exploits an alternative—the trigeminal nerve in the nose—to detect a few strong scents. The nerve typically helps detect the temperature of inhaled air or the presence of irritants. (Some users may experience a paywall.)

Companies developing new weight loss drugs

In recent years, weight loss drugs made a tremendous amount of money for Novo Nordisk and Eli Lilly. Other companies are developing new drugs to break into the market. This piece is a concise overview of companies creating and testing new drugs, how far along they are, and what Novo Nordisk and Eli Lilly are doing to compete with these emerging rivals.

Evidence of opium use dates to as early as 5000 BCE

Archaeological evidence shows the use of the poppy plant for its pain-killing properties likely originated in the Mediterranean before making its way to the East and West via trade. It has since inspired two eponymous wars, and highly addictive derivatives of the naturally occurring substance have led to an ongoing overdose crisis.

Mapping where the drug captagon is seized worldwide

In the 1960s, Captagon was patented in Germany as a stimulant similar to amphetamines. It was prescribed for a time to address narcolepsy, ADHD, and other conditions. As its addictiveness and psychosis-inducing quality became more apparent, the drug has been banned in many countries. A robust illicit manufacturing of the drug endures in the Middle East, especially in Syria and Lebanon. Track locations where the drug has been seized on this updated map.

Doctors ignored women's pain as a nurse replaced their fentanyl with saline

This five-part podcast series, produced by Serial Productions, focuses on the experiences of women undergoing fertility treatments at a Yale clinic where a nurse secretly replaced pain medication with saline solution. This led to women experiencing excruciating pain during procedures, but the clinic downplayed or ignored their complaints.

Researchers are investigating if nanoparticle treatments could combat allergies

In rodent work, Northwestern University’s Evan Scott (now at the University of Virginia) and his colleagues have been trying to attack allergies with specially designed nanoparticles—miniscule lab-made objects that can penetrate cells. They stud the nanoparticles with a tiny bit of the allergen specific to the allergy (i.e. cashew protein for cashew allergy) and antibodies that shut down allergic response processes.

Research advances suggest death takes much longer than we realized

Recent research indicates that organs, including the brain, are better at handling a lack of oxygen after the heart stops beating than previously known. Such findings may open up possibilities that include someday reversing certain death processes and expanding the availability of organs available for organ donations. (Some users may experience a paywall.)

Smell retraining can help people with anosmia learn to smell again

Olfactory training, which involves repeatedly smelling a selection of strong odors, teaches your brain to familiarize itself with experiencing smells over a lengthy period, typically multiple months. This can be useful for patients who lose their sense of smell for myriad reasons.

The story of the Sackler empire behind highly addictive OxyContin

This investigative report examines how the Sackler family built its fortune through Purdue Pharma’s aggressive marketing of OxyContin, a highly addictive painkiller. Through 2017, the drug had generated more than $30B in sales for Purdue Pharma, controlled by the Sacklers.

There's a new (contested) physiological explanation for near-death experiences based on analysis of the brains of resuscitated coma and cardiac arrest patients.

Opium's history traces from religious use to mass-market commercial products

Religious or medical use of opium was present across Europe and Asia as early as 5000 BCE. By the 16th century, humanity had come to see opium as more than medicine: It was a marketable product. This perspective also defines today's relationship with opioids, highly addictive painkillers at the heart of an ongoing drug crisis.

Emerging research suggests that cannabis, used by about 9% of American adults as a sleep aid, may suppress rapid eye movement and lead to worse quality sleep and fewer remembered dreams.

Thanatology is the study of death and dying.