What is excessive sweating?

Information for the public

Excessive sweating (also called hyperhidrosis) is when a person sweats more than is necessary to cool their body down and maintain normal body temperature. When it isn't known what has caused the excessive sweating, this is called 'primary hyperhidrosis'. This mostly affects only specific areas of the body, such as the palms of the hands and the soles of the feet, the underarms, or the face and scalp. Primary hyperhidrosis affects both men and women, and most commonly starts before the age of 18.

When it is known what has caused the excessive sweating, this is called 'secondary hyperhidrosis'. Examples of conditions that can cause secondary hyperhidrosis are an overactive thyroid, or going through the menopause. Secondary hyperhidrosis most commonly affects the whole body, rather than specific areas.

Sometimes people have surgery as a last resort to control excessive sweating of the palms, soles or underarms. During the surgery, the nerves that cause the sweating are cut which stops the sweating. However, after surgery, sweating can sometimes develop in another part of the body that was not affected before. When this happens this is called 'compensatory' sweating or 'compensatory hyperhidrosis'.