Excessive sweating affects roughly 5% of the U.S. population, or about 15 million people. If you’re soaking through shirts, leaving palm prints on paper, or sweating without any obvious trigger like heat or exercise, there’s almost certainly an identifiable reason. The causes range from a harmless (but frustrating) genetic tendency to medical conditions that need attention.
Your Body May Just Be Wired to Sweat More
The most common cause of excessive sweating is a condition called primary focal hyperhidrosis. “Primary” means there’s no underlying disease causing it, and “focal” means it hits specific areas: palms, soles of the feet, underarms, face, or head. It tends to start in childhood or adolescence, runs in families, and affects both sides of the body symmetrically. You might notice it gets worse with stress or heat, but it can also happen for no apparent reason while you’re sitting at your desk.
Doctors gauge severity using a simple four-point scale. A score of 1 means sweating is barely noticeable and doesn’t affect your day. A 2 means it’s tolerable but sometimes gets in the way. A 3 means it’s barely tolerable and frequently interferes with daily life. A 4 means the sweating is constant and intolerable. If you’d rate yourself at a 3 or 4, that’s the threshold where treatment usually makes sense.
Medical Conditions That Cause Sweating
When sweating is caused by something else going on in your body, it’s called secondary hyperhidrosis. The key difference: it tends to be generalized (all over your body, not just your palms or pits) and it often starts in adulthood rather than in your teens. Several common conditions can trigger it.
An overactive thyroid is one of the most frequent culprits. Your thyroid controls your metabolic rate, and when it’s running too fast, your body generates excess heat and sweats to compensate. You’d likely also notice a racing heart, weight loss despite eating normally, or feeling jittery. Diabetes can cause sweating too, particularly when blood sugar drops low. That type of sweating often comes on suddenly and is paired with shakiness, confusion, or hunger.
Hormonal shifts during menopause are another major trigger. Hot flashes cause a sudden wave of heat in the upper body, followed by flushing and sweating that can last several minutes. These can happen during the day or wake you from sleep. Other medical causes include gout, chronic alcohol use, neurological conditions, and spinal cord injuries.
Medications Are a Common Overlooked Cause
If your sweating started or worsened around the time you began a new medication, that’s probably not a coincidence. Drug-induced sweating is more common than most people realize, and several widely prescribed medication classes are known to cause it.
Antidepressants top the list. SSRIs like citalopram, escitalopram, fluoxetine, and paroxetine all list sweating as a side effect. So do SNRIs like venlafaxine and older tricyclic antidepressants. Pain medications, including codeine, tramadol, morphine, and oxycodone, frequently cause sweating as well. Steroid medications like prednisone and dexamethasone can do it by affecting hormone levels, and thyroid replacement medications like levothyroxine can tip you into excess sweating if the dose is slightly too high. Even stimulant medications used for ADHD have been reported to trigger it.
If you suspect a medication is the cause, don’t stop taking it on your own. But it’s worth a conversation with whoever prescribed it, because a dose adjustment or switch to a different drug in the same class can sometimes resolve the problem.
Night Sweats Have Their Own Set of Causes
Sweating that happens primarily at night deserves separate attention because the causes don’t always overlap with daytime sweating. The most common reasons include menopause-related hot flashes, anxiety, medications (especially antidepressants, steroids, and painkillers), and low blood sugar episodes during sleep.
Alcohol use is a particularly common nighttime trigger that people don’t always connect. Alcohol disrupts your body’s temperature regulation, and as it metabolizes overnight, it can cause rebound sweating. Some cancers, particularly lymphomas, are known to cause drenching night sweats, often paired with unexplained weight loss or fevers. Night sweats alone don’t mean cancer, but if they’re persistent, unexplained, and soaking your sheets regularly, they’re worth getting checked.
Food and Lifestyle Triggers
Spicy foods trigger sweating through a straightforward mechanism: capsaicin, the compound that makes peppers hot, activates the same receptors your body uses to detect actual heat. Your nervous system responds by trying to cool you down. Hot beverages and meals can do the same thing simply by raising your core temperature slightly. Caffeine and alcohol both stimulate the nervous system in ways that increase perspiration. If your sweating spikes after meals, paying attention to which foods precede it can help you identify your personal triggers.
Stress and anxiety are among the most potent everyday triggers. Emotional sweating is driven by your fight-or-flight response and tends to hit the palms, soles, and underarms specifically. If you notice your sweating is worst during social situations, meetings, or moments of anticipation, anxiety may be the primary driver.
Treatment Options That Work
For focal hyperhidrosis (palms, feet, underarms), the first step is usually a clinical-strength antiperspirant containing aluminum chloride. These work by temporarily plugging sweat gland pores. They’re available over the counter in stronger concentrations than regular antiperspirants and are typically applied at night to dry skin.
If antiperspirants aren’t enough, prescription topical treatments have become available in recent years. A medicated cloth approved in 2018 reduced sweat production by at least 50% in roughly 75% of adults in clinical trials. A topical gel approved in 2024 showed meaningful improvement in sweating severity for 49 to 64% of patients, depending on the study.
Botox injections are one of the more effective options for underarm sweating, outperforming aluminum chloride in head-to-head studies. The injections block the nerve signals that tell sweat glands to activate, and results typically last several months before needing a repeat treatment. For sweaty palms and feet, iontophoresis is a long-established option. It involves placing your hands or feet in shallow water while a mild electrical current passes through the skin. Sessions take about 30 minutes daily at first, then taper to maintenance as sweating improves.
Oral medications that block the chemical messenger responsible for sweat production can help when sweating is widespread or doesn’t respond to topical treatments. These tend to cause dry mouth and other side effects, so they work best at lower doses or for situational use. A newer approach uses focused microwave energy to permanently destroy sweat glands in the underarms, sometimes in a single session.
Signs That Sweating Needs Urgent Attention
Most excessive sweating is uncomfortable but not dangerous. However, certain combinations of symptoms signal something more serious. Heavy sweating paired with dizziness, chest pain, pain in the jaw or arms, cold clammy skin, or a rapid pulse can indicate a cardiac event and needs immediate medical attention. Unexplained night sweats combined with unintentional weight loss, persistent fevers, or swollen lymph nodes should be evaluated promptly to rule out infections or malignancies.
Sweating that starts suddenly in adulthood, affects your whole body rather than specific zones, or happens primarily during sleep is more likely to have an underlying medical cause than sweating you’ve dealt with since your teens. If any of those descriptions fit, blood work to check thyroid function, blood sugar, and other markers can usually identify or rule out the most common culprits quickly.