What are the causes of hyperhidrosis?

What causes primary focal hyperhidrosis?

Primary focal hyperhidrosis is usually classed as idiopathic, which means that there is no identified cause, but most experts believe that the condition is caused by problems with the sympathetic nervous system. The sympathetic nervous system is responsible for controlling most of the actions we carry out without conscious thought, for example, the movement and digestion of food through the body. The sympathetic nervous system uses sweating as a means of cooling the body down and when the body gets too hot, the sympathetic nervous system sends signals to the sweat glands to start producing sweat. Once the sweat has been secreted, it cools on the skin, making the body colder.

Experts believe that primary hyperhidrosis is caused by problems with the part of the brain that is responsible for sending signals to the sweat glands, which means that the sweat glands secrete sweat even when the body is not too hot.

There is also evidence to suggest that primary focal hyperhidrosis can run in families, and around 1 in 4 people with the condition have a close relative who also sweats excessively. Family history of a condition indicates that a genetic mutation may have occurred.

What causes secondary hyperhidrosis?

Secondary hyperhidrosis has an underlying cause and there are many different conditions that may cause excessive sweating. Common causes of secondary hyperhidrosis include:

  • The menopause
  • Abuse of drugs or alcohol
  • Alcohol or drug withdrawal
  • Over-active thyroid gland

Less common conditions which cause secondary hyperhidrosis include:

  • Leukaemia or lymphoma (cancers of the white blood cells)
  • HIV
  • Tuberculosis
  • Parkinson's disease

Taking certain types of medication can also cause excessive sweating. These medications include:

  • Anti-depressants
  • Tamoxifen, which is used to treat some cases of breast cancer
  • Gonadotrophin-releasing hormone antagonist, which is used to treat some cases of prostate cancer in men and infertility in women

What causes generalised hyperhidrosis?

Generalised hyperhidrosis is usually linked to an underlying health problem and possible causes of generalised hyperhidrosis include:

  • Anxiety disorders
  • Damage to the nerves in the spinal cord
  • Heart problems
  • Some types of infection
  • Some forms of cancer
  • Taking certain types of medication
  • Hormone imbalance due to an over-active thyroid gland