Hot flashes are your body’s heat-release system firing when it shouldn’t. They happen when the part of your brain that regulates temperature becomes overly sensitive to tiny changes, triggering a rapid cooling response: blood vessels near the skin dilate, sweat glands activate, and your heart rate jumps by 5 to 10 beats per minute. Your body temperature rises 1 to 3 degrees during an episode. The most common cause is the hormonal shift around menopause, but hot flashes can also signal other medical conditions.
What Happens in Your Brain During a Hot Flash
Your brain has a built-in thermostat located in the hypothalamus. In normal conditions, this thermostat tolerates a comfortable range of body temperatures before it triggers sweating (to cool you down) or shivering (to warm you up). That comfortable range is called the thermoneutral zone.
When estrogen levels drop, a chemical messenger called norepinephrine increases in the brain. This narrows the thermoneutral zone dramatically. Instead of tolerating normal temperature fluctuations, the brain interprets even a tiny rise in core temperature as overheating and launches a full cooling response: flushing, sweating, and rapid heartbeat. That’s the hot flash. It’s not that your body is actually overheating. Your thermostat has just become far too sensitive.
This is why estrogen-based hormone therapy works: it raises the temperature threshold at which your brain triggers sweating, effectively widening that thermoneutral zone back toward normal.
Menopause Is the Most Common Cause
The vast majority of hot flashes are linked to the menopausal transition. They can start during perimenopause, sometimes years before your last period, and continue well into postmenopause. A major study tracking women through the transition found a median total duration of 7.4 years. After the final menstrual period, hot flashes typically persisted for another 4.5 years.
Timing matters. Women who started experiencing frequent hot flashes while still in early perimenopause had the longest course, with a median duration exceeding 11.8 years. Women whose hot flashes didn’t begin until after menopause had the shortest course, around 3.4 years. So the earlier they start, the longer they tend to last.
Frequency varies widely. Some women have a few episodes a week, others have several a day. “Night sweats” are simply hot flashes that happen during sleep, and they carry their own burden. Women who report nocturnal hot flashes show increased transitions to lighter sleep stages and more awakenings per night. It’s the awareness of those episodes, waking up drenched and overheated, that correlates most strongly with overall sleep disruption.
Other Reasons You Might Get Hot Flashes
Menopause isn’t the only explanation. A wide range of conditions can trigger flushing episodes, and it’s worth knowing about them, especially if hot flashes seem unrelated to your menstrual cycle or don’t respond to hormonal treatment.
Medical conditions that cause hot flashes include thyroid disorders, certain rare tumors (such as carcinoid tumors or adrenal gland tumors), and kidney cancer. Neurological conditions and spinal cord injuries can also disrupt the body’s temperature regulation. Some medications, alcohol, and even food additives are known triggers.
Men get hot flashes too. Up to 80% of men undergoing androgen deprivation therapy for prostate cancer experience them. The mechanism is essentially the same: the withdrawal of sex hormones (in this case testosterone, which the body partially converts to estrogen) destabilizes the brain’s thermostat.
What Makes Hot Flashes Worse
Smoking is one of the strongest modifiable risk factors. Current smokers are roughly 3.5 to 3.8 times more likely to experience frequent or severe hot flashes compared to women who have never smoked. Former smokers also carry elevated risk, though not as high. If you’re dealing with persistent hot flashes and you smoke, quitting may meaningfully reduce their severity.
Depression is another significant factor. Women with depressive symptoms have higher odds of more frequent and more severe episodes. Common environmental and dietary triggers include spicy foods, caffeine, alcohol, and warm weather. These don’t cause the underlying condition, but they can push your already-sensitive thermostat over the edge.
Interestingly, body weight was not significantly associated with hot flash severity or frequency in at least one large study tracking women through the menopausal transition, despite the common assumption that higher BMI worsens symptoms.
Treatment Options That Work
Hormone therapy remains the most effective treatment for hot flashes. The North American Menopause Society’s current position is that for women under 60 or within 10 years of menopause onset, the benefits generally outweigh the risks when used for bothersome symptoms. The calculus shifts for women who are more than 10 years past menopause or over 60, where the risks of cardiovascular events and blood clots increase. Duration of treatment is individualized, with periodic check-ins to reassess whether continuing makes sense.
For women who can’t or prefer not to use hormones, the FDA approved a new class of medication in 2023. Fezolinetant (sold as Veozah) works by blocking a specific receptor in the brain’s temperature regulation pathway rather than replacing hormones. It was the first drug of its kind approved for moderate to severe menopausal hot flashes, and it demonstrated effectiveness in two phase 3 clinical trials.
What a Hot Flash Actually Feels Like
If you’re searching this question because you’re experiencing something unfamiliar, here’s what to compare it to. A typical hot flash starts as a sudden sensation of intense internal heat, usually centered in the chest, neck, and face. Your skin may turn visibly red. Sweating follows, sometimes profuse, sometimes mild. The episode usually lasts a few minutes, though some women report episodes stretching longer. Afterward, you may feel chilled as the sweat evaporates and your body overshoots in the other direction.
Night sweats follow the same pattern but can soak through clothing and sheets. Most nocturnal hot flashes occur outside of REM sleep, with only about 6% happening during dream stages. The disruption comes from the repeated awakenings, which can leave you feeling exhausted even after a full night in bed. Women in one study averaged nearly 18 awakenings per night after developing nocturnal hot flashes.
If your hot flashes are accompanied by unexplained weight loss, persistent fever, severe headaches, or other unusual symptoms, or if they don’t fit the typical menopausal pattern, they may point to one of the less common causes and are worth discussing with a healthcare provider.