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 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

Since the dawn of pain, living things have sought ways to mitigate this evolutionary warning signal. One of nature's most effective painkillers is opium, a highly addictive, milky latex extracted from poppy plants. This forms the basis of one of the most prescribed classes of modern drugs.

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.

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.

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.

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.

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.

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.)

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, indeed, addictive

Caffeine enters the brain through the bloodstream, where it blocks receptors that cause us to feel tired and enables stimulants like dopamine to increase alertness and focus. Over time, the brain begins to expect this level of stimulation, and caffeine addiction can develop. Caffeine withdrawal causes headaches, irritability, and fatigue.

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.

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.)

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).

Why Belgium is now the cocaine capital of Europe

Belgium has become Europe’s cocaine-trafficking capital. Recently, Belgian ports have seen record seizures of cocaine. In 2020, the port of Antwerp accounted for 40% of all cocaine seizures in the EU. And local authorities are struggling with the...

Formula 1 cars are the world's fastest regulated road-course racing automobiles

F1 is the highest international level of open-wheel racing, where the wheels are not covered by the car’s body, differing significantly from NASCAR, which have covered wheels.

Unlike milder fears, phobias may get in the way of proceeding with your life

Clinicians may recommend exposure therapy—exposing oneself to the thing triggering fears in some doses—as one way to help overcome a fear.

The deadly genetic disease that steals shut-eye

Few are haunted by fatal familial insomnia. This neurodegenerative disease is typically carried through bloodlines via genetic mutation of the prion protein gene, forcing the body to create abnormal and pathological protein variations that can corrupt normal versions. This article follows a musician as they attempt to come to terms with the FFI plaguing their family (and, possibly, their future).

Veterans reported single dose of ibogaine improved TBI, PTSD, anxiety, and depression

Research published in 2024 on the Central African plant-derived drug included 30 male combat vets who received ibogaine treatment in Mexico. It reported significant reductions in multiple mental health conditions and no serious side effects. Other work, however, has shown the substance can cause fatal cardiac arrhythmias, killing at least 19 people between 1990 and 2008. (Some users may encounter a paywall.)

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

'FAST': An acronym to remember stroke symptoms to look for

The primary factor in surviving a stroke is how quickly one gets the appropriate medical treatment. “FAST” refers to the four most noticeable symptoms of a stroke: face-dropping ("F"), arm weakness ("A"), speech difficulty ("S"), and "time to call 911" ("T").

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

After her fellow cult members tried to kill her with an LSD-infused hamburger, one member of the Manson Family, the murderous cult led by Charles Manson, decided to testify against the group's leader.

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Marburg virus, related to Ebola, is also extremely deadly, and has no available vaccine.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it.

The deadliest aspect of volcanic eruptions is often not lava, but pyroclastic flows—avalanches of ash, gas, and rock that can move more than half the speed of sound.

The US dollar is the most widely circulated currency in the world, and is involved in nearly 90% of global transactions

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Hedge funds, the private investment firms that trade a wide swath of financial assets, make money by imposing steep fees on investors and from the fund's investment performance.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Art theft is the third-largest source of criminal revenues worldwide, thanks in part to the subjective nature of valuing a work of art.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

11 people died from firework injuries in the US in 2024.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Hear 50 years of iconic hip-hop samples, the genre's foundational looped tracks

Despite being favored by 87% of Americans, Congress does not have term limits.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.