Hyperhidrosis is usually caused by either overactive sweat glands or an underlying medical condition. In many people, the exact reason isn’t fully known, but primary hyperhidrosis often appears to involve a problem in the nervous system that tells sweat glands to turn on when they shouldn’t.

Main causes

  • Primary hyperhidrosis: No clear medical cause is found, and it often runs in families.
  • Secondary hyperhidrosis: Caused by another condition, medication, or trigger such as:
    • Thyroid problems
    • Diabetes
    • Menopause
    • Infections like tuberculosis
    • Heart disease or heart failure
    • Parkinson’s disease
    • Some cancers, including lymphoma or leukemia
    • Certain medicines, including antidepressants and some diabetes or hormonal drugs

Common triggers

Even when hyperhidrosis is primary, sweating can be worsened by:

  • Stress, anxiety, or nervousness
  • Heat or humidity
  • Exercise
  • Spicy foods
  • Caffeine and alcohol

When to pay attention

If sweating is new, widespread, happens during sleep, or comes with symptoms like weight loss, fever, palpitations, or tremor, it can point to an underlying condition rather than primary hyperhidrosis.

A quick example: someone who has had sweaty palms since childhood may have primary hyperhidrosis, while someone who suddenly starts sweating heavily all over after starting a new medication may have secondary hyperhidrosis.