Heat exhaustion is the most likely diagnosis if someone is talking clearly

Heatstroke is sometimes missed because the patient is really sweaty

Since the condition involves losing the ability to cool oneself, clinicians sometimes see someone who has exertional heatstroke—like a high school athlete who is really sweaty—and don't realize the heat-related illness has already progressed to heatstroke. Classic heatstroke typically occurs among the very young or the elderly. (Some users may encounter a paywall.)

Heatstroke is when the body's core temperature becomes dangerously high—and needs to cool

Warning signs that the body is overheating include rapid breathing, cramps, heavy sweating, nausea, and feeling lightheaded. Drinking plenty of fluids, seeking shade, and cooling the body down as quickly as possible with icepacks can help reduce the risk of heatstroke.

Heatstroke occurs when the body reaches 104°F or higher and can't cool itself

Untreated, this medical emergency can result in permanent disability or death. Someone suffering from heatstroke—defined as a core temperature of 104 degrees Fahrenheit but sometimes as high as 106 degrees Fahrenheit—may appear confused and require immediate cooling, ideally with an ice bath.

Exertional heatstroke is a top killer of athletes and soldiers-in-training

Often characterized by collapsing while exercising in the heat with intense sweating, this type of heatstroke among otherwise healthy people occurs when the body loses the ability to cool itself during intense exercise and the body's core temperature has risen to 104 degrees Fahrenheit or higher and cannot cool itself. If treated quickly, it's often survivable, though it can cause lasting damage.

Heatstroke can reprogram your DNA, putting survivors at risk of future health problems

Severe illness from extreme heat exposure can alter DNA through epigenetics—turning genes "on" or "off" to shape disease risk. These changes can place an organism at greater risk of future health complications—unlike the epigenetic changes produced by moderate, repeated heat exposures.

Certain medications that affect blood flow or mood boost the risk of heatstroke

Drugs that narrow blood vessels, beta blockers that regulate blood pressure, diuretics, antidepressants, and antipsychotics can all affect the body's ability to regulate its internal body temperature, and so individuals taking these medications need to take special care in extreme heat and when exercising in hot conditions.

Key symptoms of burnout can be both mental and physical

Burnout can be accompanied by several symptoms, including low energy and chronic fatigue, trouble concentrating, difficulty sleeping, and depression. It may even manifest physically as musculoskeletal pain, headaches, stomach and intestinal pain, and more. More intense cases have been linked to cardiovascular and mental health disorders.

What is a heat dome?

The world is seeing regular heat waves with multiple causes, including so-called "heat domes," a term rising in use in recent years. A heat dome occurs when the atmosphere traps hot ocean air like a lid or cap, creating stifling conditions and resulting in extended periods of heat. See an illustration of this phenomenon and read how it works with this brief explainer.

'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").

When to see a doctor over memory lapses

Memory includes various, distinct functions, like working memory (storing information temporarily) and procedural memory (your body's ability to perform a task unconsciously). Forgetting a word or losing your keys can feel like red flag memory lapses, but they are, in fact, language or attention problems, not memory ones. However, a lapse on top of stress, lack of sleep, chronic dysfunction, or an injury may be a red flag to see your doctor.

Terminal lucidity is the phenomenon of sudden, heightened mental clarity when on the verge of death

The "Let's Talk Near Death" podcast explores phenomena around the end of life, inviting guests to recount their own experiences. This episode focuses on the phenomenon known as "terminal lucidity," where patients experience clarity, vivid memory recall, and more, typically following a heart attack, stroke, or other trauma.

Dizziness may describe lightheadedness and imbalance, not the spinning of vertigo

Dizziness is defined as an altered sense of spatial orientation, and may include feeling like you might fall over. Vertigo is associated with feeling like you are spinning or your surroundings are spinning.

How seizures (potentially) alter consciousness

Seizures occur when intense electrical activity floods the brain, prompting significant loss of self-control and a variety of sensory disruptions and hallucinations. Cultures interpret the episodes differently, with many contemporary norms viewing them as negative while others characterize them as intense spiritual occasions. Author Fyodor Dostoyevsky viewed his seizures this way, as well as cultures in Mongolia, some Shamanic indigenous religions, and others.

Repeated head injuries can lead to CTE and early dementia

Chronic traumatic encephalopathy is a progressive neurodegenerative disease caused by repeated trauma to the head. The condition has become a particular concern in sports like football and soccer, from youth to professional leagues, where repeated low-level concussive events are likely.

Measles symptoms range from fever to pneumonia and encephalitis

While less common, most measles-related deaths come from secondary conditions such as pneumonia (one to six cases per 100 patients) and encephalitis (one case per 1,000 patients). Blindness, which is rare, may arise from corneal ulceration.

Feels-like temperature indicates how our skin will feel

When the wind is moving faster, we tend to feel colder due to the so-called "wind chill," which cools our bodies by moving heat away from them and making water evaporate faster. On the other hand, high levels of humidity can make us feel 10 degrees warmer at times.

What happens to the brain during migraine?

Migraine is a neurological condition that can cause debilitating symptoms across various bodily functions. So, what exactly is happening in the brain during these attacks? This five-minute video briefly overviews the internal machinations behind the painful episodes. An incapacitating headache is a common symptom of migraine, though migraine can occur without any headache.

Brain death is a medical diagnosis without any wiggle room

Seeking to resolve long-standing variations between hospitals and state procedures, in 2023 several expert groups published comprehensive step-by-step guidance for clinicians to follow when determining brain death in kids and adults. Among other guidelines, it stated that doctors don't need to get family consent to do the tests needed to make this determination.

Panic attacks are intense fear episodes that often occur without a clear trigger

Unlike typical fear responses to real danger, panic attacks can mimic serious health problems, such as heart attacks. Sweating during a panic attack may seem random, but it's a leftover survival mechanism that made it easier for our ancestors to escape by slipping out of an attacker’s grasp.

Hemorrhagic strokes make up roughly 13% of stroke events

A hemorrhagic stroke occurs when a faulty blood vessel within the brain bleeds. Though this is less common than an ischemic stroke, it is often far more deadly. This in-depth resource from the American Stroke Association provides a comprehensive overview of the two main subtypes of hemorrhagic stroke along with a useful animation of the condition.

Hearing loss can affect balance and make falls more likely

For reasons that are not yet fully understood, hearing loss seems to increase the risk of falls. One explanation is that reduced environmental awareness due to hearing loss may put people at greater risk. Another theory is that the brain has to work harder to process sound with hearing loss and that cognitive load may also boost the chances of falls. One study found that for every 10 decibel increase in hearing loss, there was a 1.4 fold increased odds of falling in the preceding 12 months.

Gibberish, urine, and utter chaos: what happens when you sleepwalk

Sleepwalking, or somnambulism, occurs most frequently in children who are in the deepest stages of sleep. REM, the sleep stage in which most people dream, often causes temporary muscle paralysis, so it’s only when sleepers pass to the deeper stages of sleep that sleepwalking—and sleep talking—can occur.

Cholera was called the 'Blue Death'

In the mid-1800s—when John Snow identified cholera in London—the disease was known simply as the "Blue Death." That's because blood would thicken in patients' veins when they were struggling with extreme dehydration. As a result, their skin would turn a blueish hue as their blood was starved of oxygen.

The mysterious details of Stalin's death

The 73-year-old dictator of the Soviet Union died March 5, 1953, officially from a stroke, on top of nearly a decade of significant medical issues. But evidence suggests the longtime leader might have been poisoned less than a week before at an intimate gathering of Stalin's closest confidantes and advisors. Explore the current evidence for Stalin's alleged murder here.

Yawning helps regulate heat in and around the skull

All vertebrates, including solitary animals, exhibit yawning behavior, and, despite long-standing beliefs, studies show no correlation between yawning and oxygen levels. Contagious yawning may enhance group coordination and vigilance in animals and involves advanced social cognitive mechanisms.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

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.

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

Animal phobias are likely the most common type of phobias, followed by an extreme fear of heights.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

How the most famous Ebola book, The Hot Zone, which sold 3.5 million copies and was translated into 30 languages, got aspects of the disease so wrong.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

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

This real-time tracking of the hantavirus cruise ship outbreak in May 2026 offers a unique glimpse into the global reach of the outbreak and whether the virus sickened passengers and their communities around the world.

A pickleball's loud 'pop' sound can reach 120 decibels, which is equivalent to a hammer hitting a nail

Browse a detailed visual analysis of over 200,000 similes—comparisons that often use 'like' or 'as'—from popular fiction to see how frequently writers the same idiomatic expressions.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

Meet the 56 signers of the Declaration of Independence—most of whom didn't put pen to paper until August 2, 1776—and see their original signatures.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

The identity of the Tank Man in the iconic photo from the 1989 Tiananmen Square protests remains unknown and was possibly killed.

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.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'