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

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.

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.

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.

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.

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.

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.

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.

Opioids mimic naturally produced endorphins to dull pain.

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.'

Narcan is an opioid antagonist that can rapidly reverse overdoses

Naloxone, also known by the brand name Narcan, is an opioid-overdose reversal medication that typically begins working within a few minutes. An opioid antagonist, the treatment attaches to opioid receptors without activating them, forcing opioid molecules out of their respective receptors and allowing users' breathing rates to normalize.

Overuse of opioids can lead to hypersensitivity to pain.

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.

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.

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.

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.

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 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.

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.

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.

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.

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

Only a fraction of LSD reaches the brain, but it concentrates in key regions

When taken, LSD is absorbed quickly (often within an hour of ingestion) and exerts its effects primarily by binding to serotonin receptors. While only a small amount enters the brain, it's active in regions controlling the visual and auditory senses, potentially driving its psychedelic effects. The drug doesn't linger in the body, and is typically undetectable within a day.

This is the human brain on the world's strongest psychedelic

Within seconds of inhaling a high dose of vaporized synthetic 5-MeO-DMT—a lab-produced substance that otherwise is naturally derived from the glands of the Colorado River toad—it induced slow brain waves. Such waves are typically associated with unconsciousness due to a coma or anesthesia, perhaps explaining why users describe feeling like everything falls away. The compound is currently in clinical trials for treating depression.

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.

Fame can trigger addictive, drug-like highs in the brain

Differences in the type of fame, such as movie stardom, sports, and internet virality, can produce varying degrees of dependence on individuals based on their age and background. Some individuals—particularly children—can develop drug-seeking behavior as they pursue continuous dopamine spikes if they lack an existing sense of fulfillment from elsewhere.

What is the blood brain barrier?

Every blood vessel is lined with endothelial cells that act as filters between blood and the rest of the body. In the brain, these cells are tightly packed together to keep a close watch on what substances can access the vital organ. This protective measure poses an obstacle to drugmakers looking to deliver drugs to the well-defended brain for conditions like Alzheimer's. Watch a quick overview here.

A new daily MS pill is seeking regulatory approval in 2026

In clinical trials, Roche's fenebrutinib showed promise treating primary progressive MS and doubling relapse-free time in patients with relapsing MS as compared to existing treatment. But some liver damage and two possible drug-related deaths in the trials may make it difficult for the drug to net approval. (Some users may encounter a paywall.)

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.

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).

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.

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.

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.

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.

Coffee is addictive, and those going through withdrawal often experience headaches and fatigue.

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.

'Susan's Brain': what happens to the brain during addiction

This engaging animation from Harvard Online breaks down the neuroscience of addiction through the story of “Susan’s brain,” demonstrating how addictive substances hijack normal reward pathways. Through clear visual metaphors and approachable narration, it explains complex brain chemistry in understandable terms.

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.

Chronic drug use can cause neurological changes in the brain

Neuroscientist Judy Grisel breaks down the biology of addiction, examining how drugs hijack the brain’s natural reward system and create lasting neural changes. The physiological and neurological impacts of chronic drug use require a multifaceted treatment approach.

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.

The federal agents who followed Billie Holiday

After the success of "Strange Fruit," the Federal Bureau of Narcotics began surveilling Holiday on suspicion that she was using heroin. Jimmy Fletcher, an agent tasked with following her to clubs and parties, later said that they became quite close. "She was the type who would make anyone sympathetic because she was the loving type," he was reported as saying.

Love and heartbreak trigger powerful, neurochemical-driven changes in the body

The feeling of falling in love floods the brain with dopamine, oxytocin and serotonin, which collectively dull pain and boost immunity. However, the loss of these chemicals during a break-up produces withdrawal-like symptoms and heart issues, such as high blood pressure.

DBS effectiveness in treating addiction remains uncertain amid inconsistent results

Critics argue that deep brain stimulation should be considered a last resort and not a scalable solution, given its high costs and trials limited to small samples. However, it has helped some patients manage severe opioid use disorder when conventional methods didn’t work.

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.)

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.

How four types of psychedelics affect the brain

Brain imaging shows that ayahuasca, MDMA, DMT, and psilocybin profoundly affect neural activity, giving rise to higher states of introspection and consciousness. This article details exactly how each of these drugs physically affects the brain and what that means for mental health treatment. Some of these drugs quiet the brain or trigger the release of neurochemicals associated with mood regulation and learning.

How can octopuses and MDMA help scientists understand the human brain?

Research shows that psychedelics may induce something called "critical periods" in the adult brain, which can make our brains more open to learning and changing, like they once were back in early childhood. Psychedelics similarly change how social creatures like octopuses behave, which demonstrates that these animals could help us better understand our own neurobiology.

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.

HFMD can survive on surfaces for days at a time

That's why the virus can be transmitted via fomites—surfaces that have virus on them like doorknobs, kids toys, etc. These viruses are resilient—they are often even resistant to freezing (and are frequently stored at freezing temperatures in lab settings).