Sudden, unexplained sweating in men usually points to one of a handful of causes: a medication change, a hormonal shift, an underlying health condition, or a lifestyle trigger you haven’t connected to the problem yet. Unlike the kind of excessive sweating some people have had since adolescence (primary hyperhidrosis), new-onset sweating that comes on without warning is called secondary hyperhidrosis, and it typically means something in your body has changed.
The good news is that most causes are identifiable and treatable. The key is figuring out what shifted.
Medications Are the Most Overlooked Cause
If you recently started, stopped, or changed the dose of a medication, that’s the first place to look. Drug-induced sweating is surprisingly common, and many men don’t make the connection because the sweating can start days or weeks after the medication change.
The drug classes most strongly linked to excessive sweating include antidepressants (SSRIs like citalopram, escitalopram, fluoxetine, and paroxetine, as well as tricyclics and SNRIs like venlafaxine), opioid painkillers (codeine, tramadol, oxycodone, morphine), and certain medications for dementia. These drugs trigger sweating through different pathways. SSRIs and SNRIs affect the brain’s temperature-regulation center. Opioids cause a chain reaction that releases histamine, which in turn ramps up sweat gland activity. Tricyclic antidepressants stimulate the same receptors that your fight-or-flight system uses.
Some diabetes medications and hormonal treatments can also cause sweating as a side effect. If the timing lines up with a prescription change, talk to your prescriber about alternatives or dose adjustments rather than stopping anything on your own.
Thyroid Problems and Other Hormonal Shifts
An overactive thyroid (hyperthyroidism) is one of the most common medical causes of sudden sweating in men. When the thyroid gland produces too many hormones, your metabolism accelerates. Your body generates more heat than it can efficiently shed, so you sweat more, feel warm in rooms that don’t bother anyone else, and may notice your skin feels damp much of the time. Other telltale signs include unexplained weight loss, a racing heartbeat, nervousness, and difficulty sleeping.
Low testosterone is a less common but real possibility, particularly in men over 40. Declining testosterone can disrupt temperature regulation and cause episodes of sweating, including night sweats. The hallmark is that it almost always shows up alongside sexual symptoms like low libido or erectile problems, and diagnosis requires repeatedly low morning testosterone levels on blood tests. If sweating is your only new symptom, low testosterone is unlikely to be the explanation.
Blood Sugar Drops
Sweating is one of the earliest warning signs of low blood sugar (hypoglycemia). When blood glucose drops below about 70 mg/dL, the body activates its stress response, which triggers sweating, shakiness, a fast heartbeat, and sometimes confusion or irritability. This is most common in men with diabetes who take insulin or certain oral medications, but it can also happen in people without diabetes after skipping meals, drinking alcohol on an empty stomach, or during intense exercise.
If your sweating episodes come with shakiness and improve after eating, blood sugar is worth investigating.
Sleep Apnea and Night Sweats
If the sweating mainly happens at night, obstructive sleep apnea deserves serious consideration. About 31% of men with sleep apnea report frequent night sweats (three or more times per week), compared to just 9% of men in the general population. Sleep apnea causes repeated airway closures during sleep, which drops oxygen levels and forces the body into a stress state. That stress response produces sweating, elevated blood pressure, and frequent awakenings.
Research from an Icelandic sleep cohort found that both sweating and blood pressure improved objectively when sleep apnea was treated with a breathing device. If you also snore loudly, wake up tired despite a full night’s sleep, or your partner has noticed you gasping or stopping breathing at night, a sleep study can confirm or rule this out quickly.
Other Medical Conditions Worth Knowing About
Several other conditions can cause sudden sweating in men:
- Infections: Bacterial and viral infections commonly cause sweating as part of the fever response. Tuberculosis, HIV, and endocarditis (a heart valve infection) are among the infections known for causing drenching night sweats specifically.
- Certain cancers: Lymphoma is the cancer most classically associated with night sweats, often accompanied by unexplained weight loss and fevers. This is uncommon, but it’s the reason doctors take new-onset night sweats seriously.
- Nervous system disorders: Conditions affecting the autonomic nervous system (the part that controls sweating, heart rate, and digestion) can cause unpredictable sweating episodes.
- Anxiety disorders: Chronic anxiety and panic attacks activate the same stress pathways that cause sweating during exercise or danger. If your sweating spikes during periods of worry or comes with chest tightness, racing thoughts, or a sense of dread, anxiety could be the driver.
Lifestyle Triggers That Sneak Up on You
Sometimes the cause isn’t medical at all. Increased caffeine intake, spicy foods, and alcohol are all common triggers for sudden sweating. Capsaicin (the compound that makes peppers hot) literally raises your body temperature, and your sweat glands respond exactly the way they would to a warm room. Alcohol dilates blood vessels near the skin, which increases heat loss and triggers compensatory sweating.
Weight gain is another factor men often overlook. Even a moderate increase in body fat insulates the body, making it harder to cool down. If you’ve gained 10 to 15 pounds recently and notice you’re sweating more, the two are likely connected. Stress and poor sleep also lower the threshold at which your body starts sweating, so a period of high stress at work or disrupted sleep can show up as a seemingly random increase in sweating.
What You Can Do Right Now
Start by tracking when the sweating happens. Is it constant, or does it come in episodes? Is it worse at night, during the day, or both? Does it affect your whole body or just your underarms, palms, or face? These details help narrow the cause and will be useful if you see a doctor.
For managing the sweating itself while you sort out the cause, clinical-strength antiperspirants containing 10% to 15% aluminum chloride hexahydrate are the standard first step for underarm sweating. These are available over the counter and work best when applied to dry skin at night. Wearing moisture-wicking fabrics, reducing caffeine and alcohol, and keeping your bedroom cool (especially if night sweats are the issue) can also make a meaningful difference.
If the sweating started suddenly, happens at night and wakes you up, or comes with other symptoms like unexplained weight loss, fever, a persistent cough, or a rapid heartbeat, those combinations warrant a medical evaluation. A doctor can check your thyroid function, blood sugar, testosterone levels, and screen for infections or other conditions with straightforward blood tests. Most causes of sudden sweating in men are highly treatable once identified.