For a woman in her mid-40s to mid-50s, it arrives without warning. She wakes up, overheated, wondering why it’s so hot in the house—until she sees the thermostat is set for 70 degrees, same as always. Or, she’s midway through a work presentation when heat rises from her chest to her face, and she wonders if the flush on her cheeks is visible to everyone in the room. 

It’s a hot flash—a rite of passage for the majority of women in either perimenopause, the years leading up to menopause, or the years beyond it. Menopause itself is diagnosed after 12 consecutive months without a period, but the hot flashes don’t always get the memo.

Here’s everything doctors currently know about hot flashes.

What is a hot flash, and who gets them?

Hot flashes are a sudden heat flare up often paired with flushed skin and sweating. They don’t usually last long, between a minute and five minutes in duration.

Most women experience a hot flash about four and a half to five years after their last period, Dr. Monica Christmas, an OB/GYN at University of Chicago Medicine and director of its menopause program tells Popular Science. She also is the associate medical director of the nonprofit Menopause Society, which provides healthcare professionals with tools and resources to support women through the transition.

Women have grappled with hot flashes—whether simply annoying or genuinely debilitating—for centuries. In 1582, Dr. Jean Liebault of France was among the first to document the phenomenon. But while we know much more about hot flashes and night sweats than Liebault ever did, one question still stumps experts. 

“What we can’t answer is why doesn’t everybody get them,” Christmas says. “Because everybody doesn’t get them. I have patients that will say, ‘I don’t know,’ if I say, ‘Are you having any hot flashes or night sweats?’ And as soon as they say that, I’m like, ‘You’re not having them.’” 

What’s actually happening inside women’s bodies during a hot flash? 

During a hot flash, a woman might feel like she’s spiking a high fever, but physiologically, that’s not what is happening. As women approach menopause and the ovaries begin to make less estrogen, the brain’s internal thermostat—the hypothalamus—becomes hypersensitive to even small shifts in temperature, Christmas says.

The body “thinks” it’s overheating, even when the actual temperature hasn’t changed much. In response, our bodies try to cool us down. Blood vessels dilate, which is supposed to help dissipate some of that heat, but then that triggers a sweating reflex.

“Many people will say, ‘I feel this out of nowhere, this surge of warmth that typically is from the nipple line up,’” she says. “And then as soon as the heat came on, and I felt like I was internally heated up or on fire, I start to sweat.” 

How do women experience hot flashes differently? 

Exactly how an individual woman experiences hot flashes varies wildly. Some describe very mild symptoms. Others grapple with profuse sweating. Some experience only hot flashes during the day, while some have regular night sweats. About four in five women experience them at some point during the menopause transition, according to the American College of Obstetricians & Gynecologists.

“There’s a lot of variability,” Christmas says. Common triggers include alcohol, caffeine, high-sugar and highly processed foods, along with stress.

Black women also are more likely to experience more severe and longer-lasting symptoms, sometimes up to 11 years, she says. And research also shows that women with more severe, longer-lasting hot flashes and night sweats appear to be at higher risk of cardiovascular disease.

That doesn’t mean treating hot flashes automatically lowers heart risk, Christmas says. But it does reinforce that these women deserve particularly careful attention to blood pressure, cholesterol, and lifestyle. “I want to make sure I’m doing everything possible to minimize that risk,” she says when she treats her patients. 

There’s more to hot flashes than hormonal changes

For decades, the entire process was blamed purely on estrogen loss, Christmas says. But that explanation left some unanswered questions. 

“That doesn’t explain why every menopausal woman doesn’t have night sweats,” she says. “And it also doesn’t quite explain why we can sometimes start to experience them during the perimenopause transition because during perimenopause, people still have some estrogen.” 

Newer research now is telling a more complex story. When the brain recognizes that a woman’s estrogen levels are low, nerve cells in the hypothalamus called KNDy neurons (pronounced “candy”) become overactive, releasing neurotransmitters, which are chemical signals the brain uses to send messages throughout the body. These neurotransmitters include kisspeptin, dynorphin, and neurokinin B. 

“It’s actually those neurotransmitters that seem to have more of an impact on our ability to regulate our internal temperature,” Christmas says. “They’re not hormones.” 

What to do if you get a hot flash

For women in the middle of their hot flash years—along with the 10 percent of menopausal women who continue to experience them—there are treatments. 

Estrogen-based hormone therapy can help, but not every woman, including those with a history of blood clots or breast cancer, can take hormone therapy. 

Fortunately, researchers’ new understanding about the role of KNDy neurons has allowed for new treatments that block the brain signals that trigger hot flashes in the first place. The FDA approved a new drug called Veozah (it’s chemical name is fezolinetant) in 2023. It targets the neurokinin 3 receptor, which plays a key role in regulating body temperature. 

Lynkuet, another drug (with the chemical name elinzanetant), came along in 2025. It blocks both the neurokinin 1 and neurokinin 3 receptors, interrupting the process that triggers hot flashes at two points instead of one. 

Other medications can also provide relief, though weren’t originally developed for hot flashes, Christmas says. Some SSRIs and SNRIs; gabapentin, a neurologic medication; and oxybutynin, used for overactive bladder, are all used off-label for hot flashes and night sweats. 

Cognitive behavioral therapy and hypnosis also have been shown to reduce hot flashes. “I’m menopausal, too, so I know if I’m under a lot of stress or in a stressful situation, I’m going to probably have more hot flashes than not,” Christmas says. 

“So there’s certainly something about being able to calm our central nervous system down that seems to have an impact, too.”

If you’re struggling with hot flashes, Christmas recommends seeing your healthcare provider for help. Treatments are available. What’s more, in some cases, hot flashes or night sweats could signal other issues, including thyroid disorders, cancer, and infections, among others. 

But bottom line, when it comes to hot flashes, you don’t have to sweat them out.

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In 1076, a Dutch nobleman named Duke Godfrey “the Hunchback” of Lower Lorraine was murdered in a most unusual way. Some medieval historians tried to describe what happened in polite terms by saying that Godfrey was attacked after he had “withdrawn.” What they meant was that he sat down to use the bathroom and an assassin hiding in the toilet speared him from below. Ouch! 

Of course, your chances of meeting a similar end are pretty slim. But that doesn’t mean that doing your business is always safe. These are some of the strangest and most surprising ways that toilets have killed people.

Bathrooms have many hazards

The kitchen, with its sharp knives and hot stove, is often thought of as the most dangerous room in the home. But according to the CDC, up to 80 percent of home falls occur in the bathroom, due to the slippery, hard surfaces of tile floors and bathtubs. 

In the U.S. alone, about 40,000 injuries per year are specifically related to toilets. People can get pinched by the toilet seat while getting up or sitting down, and under rare circumstances, toilet bowls may collapse under a person’s weight. 

While statistics on toilet-related deaths are not specifically tracked, there are a number of ways that toilets can kill. Babies can drown in toilet bowls, and seniors can suffer serious falls after standing up from using the toilet, especially if they hit their head as they fall. Safeguards like bathroom handrails or locks on toilet lids can help reduce the risk of these incidents in homes.

At least some toilet-related deaths are from people trying to poop while constipated. Straining to poop puts strain on your heart, especially when you hold your breath while pushing (an action called the Valsalva maneuver). This can spike your blood pressure and even cut off oxygen flow to your brain. 

To minimize risk, doctors recommend that you take chronic constipation seriously, especially if you have a heart condition. Some doctors also advise squat toilets as the healthier option overall. When you use a squat toilet, poop can pass more easily out of your body and with less straining than when you use a seated toilet. 

Beware of pit toilets, especially if you’re meeting German nobility

Each toilet design comes with unique hazards. Before modern plumbing and sanitation, toilets were simply pits, dug as deep as possible and sometimes connected to underground water sources. 

Historically, these long shafts and dark waterways could prove deadly to people who accidentally tumbled in. In places where pit latrines are still used today, such as parts of rural Africa, they remain a safety concern and an occasional cause of death, especially for children.

Perhaps the most dramatic example of the literal pitfalls of this type of toilet design occurred in 1184 at the cathedral of Erfurt in Germany. A meeting of nobles called by King Henry VI to settle a land dispute dissolved into chaos when the cathedral’s wooden floorboards collapsed. 

Some 60 people plummeted through the floor into the latrine cesspit below, where they drowned in what became known as “the Erfurt Latrine Disaster.” The few survivors included the king and the local archbishop, who had been seated above floor level in a stone alcove.

A deadly WWII submarine toilet disaster

Aboard ships and submarines, faulty plumbing can easily cause water to leak into a vessel, and there have been subsequent cases of fatal drowning. 

In 1945, a German submarine called U-1206 was sent to the North Sea, fitted with state-of-the-art plumbing that expelled waste into the surrounding ocean through a series of valves. 

However, flushing the valve system was complex. After only eight days at sea, the young captain of U-1206 flushed incorrectly, causing the plumbing to backfire. Sewage flooded in and soaked the submarine’s batteries, releasing deadly chlorine gas that forced the crew to surface and evacuate. 

Three men drowned trying to escape the sinking vessel, and the rest were captured by Allied forces: All because of a toilet.

Metal toilets can pose real risks

On at least two occasions, U.S. prisoners have died from electrocution due to metal prison toilets. One of these prisoners was Michael Anderson Godwin of South Carolina, who was convicted of murder in 1983. 

In 1989, Godwin was fixing the TV in his cell while sitting on the toilet and placed a wire in his mouth, resulting in a fatal electric shock. In a bit of grim irony, Godwin had previously had his sentence reduced and avoided execution by electric chair. 

Similarly, in 1997, Laurence Baker of Pittsburgh died of electrocution on his cell toilet, due to the current from homemade earphones he had plugged into the TV. 

If you find yourself using a metal toilet, best to avoid electric devices altogether.

In 2016, a snake attacked from a toilet bowl

There’s probably not a human assassin lurking in your toilet bowl like the one who lay in wait for Godfrey. But what about a dangerous animal? 

Rats and snakes have been known to crawl out of toilet bowls, especially after flooding or heavy rain, as rising water levels can force animals to take shelter in sewer pipes. 

For instance, in 2016, a python bit a man using a toilet in Thailand. While such an attack might be painful and shocking, it’s still very rare, and very, very unlikely to be fatal.

Venomous spiders can lurk in outhouses

It’s best to exercise caution when using outdoor toilets because of a different kind of visitor. Attracted by the presence of flies, venomous widow spiders such as the black widow and its Australian cousin, the redback, are infamous for spinning webs under outdoor toilet seats. 

Before modern indoor plumbing, the phenomenon of these spiders biting people who disturbed them was so common that it formed the focus of the earliest medical study on black widow bites. Published in 1927, the study noted fifteen such cases treated at Los Angeles General Hospital “in recent years.” 

In 1971, Australian country singer Slim Newton even released a comedy song called “The Redback on the Toilet Seat,” with lyrics like “I didn’t see him in the dark, but boy, I felt his bite!” (Technically, only female widow spiders can bite people.) 

While widow spider bites may lead to pain and infection, they are rarely fatal thanks to modern antivenin. The last known death from a black widow bite was in 1983. In Australia, a death from severe infection following a redback bite made headlines in 2016 because it was the first such incident in more than 50 years. 

For the record, the 2016 redback victim was not bitten on the toilet. However, that same year, another man in Australia was bitten by a redback while using the toilet, on two separate occasions. 

So next time you use an outhouse, lift the seat and check before sitting down—just in case.

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