Hot flashes and night sweats are caused by disruptions to your body’s internal thermostat, a small cluster of cells in the brain’s hypothalamus. The most common trigger is shifting estrogen levels during perimenopause and menopause, which affects up to 80% of middle-aged women. But hormonal changes aren’t the only cause. Medications, underlying medical conditions, and certain lifestyle habits can all set off the same overheated, drenching response.
How Your Brain’s Thermostat Misfires
Your hypothalamus acts like a thermostat, constantly monitoring and adjusting your core body temperature. When estrogen levels fluctuate or drop, the temperature control center becomes hypersensitive. It misreads normal body temperature as too high and triggers an emergency cool-down response: your heart rate increases, blood vessels near the skin’s surface dilate to release heat, and sweat glands activate. That sudden rush of warmth, flushing, and sweating is the hot flash itself. Night sweats are the same process happening during sleep, sometimes soaking through sheets and pajamas.
The whole episode typically lasts a few minutes, but recovery (chills, clamminess) can linger. What makes this frustrating is that nothing is actually wrong with your body temperature. The thermostat just got a false alarm.
Menopause Is the Most Common Cause
For most women, hot flashes begin during perimenopause, the transitional years when periods become irregular but haven’t stopped entirely. About two-thirds of women start experiencing symptoms at this stage. The Study of Women’s Health Across the Nation (SWAN), the largest study on the topic, found that women endured hot flashes for a median of 7.4 years. Women who started having symptoms while their periods were still regular or in early perimenopause had it worse: a median of 11.8 years of symptoms. That’s far longer than the “few years” many women are told to expect.
Severity varies widely. Some women get a mild warmth in the chest and face a few times a week. Others experience dozens of intense episodes per day that interrupt work, sleep, and daily life.
Medications That Cause Sweating
Several types of medication can trigger hot flashes and night sweats independent of menopause. Antidepressants are one of the most common culprits. As many as 20% of patients taking antidepressants experience excessive sweating, with certain types (venlafaxine and bupropion in particular) carrying higher risk.
Other drug categories that commonly cause sweating include hormone-blocking medications used in breast cancer treatment, opioid pain relievers, diabetes medications that lower blood sugar, and some blood pressure drugs. If your night sweats started or worsened after beginning a new medication, that timing is worth noting.
Medical Conditions Beyond Menopause
When hot flashes or night sweats don’t have an obvious hormonal explanation, they can signal an underlying medical condition. The Mayo Clinic identifies several categories worth knowing about.
Infections: Tuberculosis is one of the classic causes of drenching night sweats. Other infections linked to night sweats include endocarditis (infection of the heart’s inner lining), bone infections, and certain fungal infections like valley fever. Infection-related sweats tend to come with other symptoms like fever, weight loss, or fatigue.
Cancers: Night sweats that are persistent and severe, especially paired with unexplained weight loss, can be an early sign of certain blood cancers. Hodgkin lymphoma, non-Hodgkin lymphoma, and leukemia are the ones most closely associated with night sweats. Rare adrenal gland tumors called pheochromocytomas can also cause episodes of sweating along with rapid heartbeat and high blood pressure.
Thyroid problems: An overactive thyroid (hyperthyroidism) speeds up your metabolism and raises body temperature, leading to heat intolerance, sweating, and flushing that can mimic menopausal hot flashes. A simple blood test can rule this in or out.
Hot Flashes in Men
Men don’t go through menopause, but they can absolutely get hot flashes. The primary cause is a sharp drop in testosterone, which most commonly happens during androgen deprivation therapy for prostate cancer. About 70% to 80% of men receiving this treatment develop hot flashes, driven by the same hypothalamic mechanism as in women: low sex hormones destabilize the brain’s thermostat.
Unlike women, most men naturally maintain testosterone levels well within the range that prevents hot flashes, even as levels decline roughly 1% per year after age 40. The problem is specific to treatment-related drops. Men on temporary androgen deprivation usually recover within three to four months of stopping treatment, but those on long-term therapy often don’t. One study found over 40% of men still had hot flashes after more than eight years of treatment.
Everyday Triggers That Make It Worse
If you already have a sensitized thermostat (from menopause, medication, or another cause), certain everyday habits can push it over the edge. These don’t cause the underlying condition, but they lower the threshold for an episode.
- Alcohol dilates blood vessels and increases blood flow, which can directly set off a flash.
- Spicy foods are a well-known trigger. Even very hot-temperature foods and drinks can do it, so letting things cool to warm or room temperature helps.
- Caffeine from coffee, tea, soda, energy drinks, and chocolate can increase frequency.
- Smoking is tied to more frequent and more severe symptoms. The longer and earlier you’ve smoked, the worse the effect.
- Stress and anxiety are reliable triggers. Relaxation techniques like deep breathing, cognitive behavioral therapy, and meditation have been shown to reduce episodes.
- Warm environments and heavy clothing raise core body temperature just enough to trip the alarm. Breathable fabrics like cotton and dressing in layers give you a way to cool down quickly.
Because triggers vary from person to person, keeping a simple journal of what you were doing, eating, or drinking before each episode can help you identify your own patterns.
Newer Treatment Options
For decades, hormone therapy was the primary treatment for moderate to severe hot flashes. It remains effective but isn’t suitable for everyone, particularly women with a history of certain cancers or blood clots. In 2023, the FDA approved the first non-hormonal medication designed specifically for menopausal hot flashes. It works by blocking a receptor in the brain (called NK3) that plays a direct role in temperature regulation, essentially calming the misfiring thermostat without involving hormones.
In clinical trials, this daily pill significantly reduced both the frequency and severity of moderate to severe hot flashes within 12 weeks. It isn’t appropriate for people with liver disease, severe kidney problems, or those taking certain other medications that affect how it’s processed in the body. But for women who can’t or prefer not to use hormones, it represents a fundamentally different approach, one that targets the specific brain circuit responsible for the problem.