Your sweat can say a lot about what’s going on inside your body—especially if you’re smellier or sweatier than usual. A bit of body odour or pit stains is normal when you’re working out, feeling anxious, or outdoors in the heat. But if you’re sweating more than usual or notice a change in your usual scent, it could signal something deeper.
Whether it’s a sudden shift or something that’s been bothering you for a while, there are times when your body’s sweat patterns can be linked to a medical issue. And even if you’ve always been someone who sweats a lot, an underlying condition might be the reason why.
Here are nine health insights your sweat might be revealing—especially if things suddenly smell stronger, feel heavier, or just seem… off.
Hormonal fluctuations
If you’re experiencing sudden hot flushes or waking up drenched in sweat, hormones could be playing a role. Shifts in oestrogen and other hormones can throw off your body’s internal thermostat, triggering overheating and sweating.
These hormonal fluctuations can happen during pregnancy, menopause, or even just before your period. In other cases, an overactive thyroid (hyperthyroidism) can make you feel excessively sweaty or heat-sensitive, as your metabolism speeds up.
Stress
You’re not imagining it—stress sweat really does smell different. That’s because most of the sweat we produce day to day comes from the eccrine glands, which release a mix of water and salt. But when you’re stressed, your apocrine glands kick in. These glands—mainly located in areas like your underarms—release sweat that contains fats, proteins and other compounds.
When that richer mix hits the bacteria on your skin, the result is a stronger, sometimes sharper odour. It’s a common reaction to anxiety or pressure.
Happiness
Turns out, your sweat may carry your mood too. Some research suggests that certain emotions can actually influence the scent of your sweat. In one study, participants were shown either funny or scary videos, and others were asked to guess what they’d watched based on the smell of their sweat. Surprisingly, many got it right.
Other studies have echoed these findings, hinting that our bodies may naturally signal emotions like joy or fear through scent—possibly as an unconscious form of communication.
Anhidrosis
It’s not always about sweating too much—sometimes the issue is not sweating enough. Anhidrosis is a condition where your body can’t sweat normally, and it can be triggered by nerve damage, certain medications or underlying medical issues, says physician Dr David Pariser.
Sweating is your body’s natural way to cool itself, so if this function is impaired, your risk of heat stroke rises. Anhidrosis can affect your entire body or just certain areas. In some cases, your body might overcompensate by sweating more in unaffected zones.
Low blood sugar
A sudden drop in blood sugar can leave you feeling flat, dizzy or nauseous—and you might notice your skin becoming pale, cold and clammy. Excessive sweating is a common sign, especially if you haven’t eaten in a while. In most cases, a sugary snack or drink can help stabilise things. But if symptoms keep coming back, it’s worth checking in with your doctor to rule out a more serious cause.
Fish odour syndrome
If your sweat has a strong, fishy smell, it could be more than just a hygiene issue. Trimethylaminuria (TMAU), or fish odour syndrome, is a rare condition where the body struggles to break down trimethylamine—a compound produced during digestion of foods like eggs, beans and fish. When this chemical builds up in the body, it can make your sweat, breath and urine smell noticeably fishy.
Hyperchlorhidrosis
If your sweat stings your eyes or leaves chalky white marks on your skin, you might be dealing with hyperchlorhidrosis—an uncommon condition where your sweat contains excess salt. It’s been linked to other health issues like cystic fibrosis, according to the National Library of Medicine, and in some cases, can lead to dangerously low sodium levels.
That said, not everyone with salty sweat has a medical problem. Some people simply sweat more salt due to their diet, how hard they exercise or their individual body chemistry.
Hyperhidrosis
If you sweat a lot for no clear reason, you might have hyperhidrosis—excessive sweating that goes beyond what’s typical. For it to be considered a medical issue, the sweating usually disrupts your daily life and isn’t triggered by heat, exercise or stress.
“You’re meant to sweat when you’re physically hot, exercising or under pressure,” says Dr Pariser. “People with primary hyperhidrosis sweat at times when they shouldn’t.”
That might mean having sweat dripping from your hands while sitting still in a cold room. If that sounds familiar, it’s worth speaking to your GP.
Lymphoma
Excessive sweating—especially at night—can sometimes be a sign of lymphoma, a type of cancer that affects the lymphatic system. While experts aren’t exactly sure why lymphoma causes this, some believe it may be the body’s response to the cancer itself or to other related symptoms.
Night sweats can also be linked to a number of other conditions, like menopause, anxiety and infections. If you’re noticing unusual sweating along with other symptoms, it’s best to speak with your GP rather than assume the worst.
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