Hyperhidrosis is excessive sweating that may occur over the entire body or only in certain parts, most commonly the underarms, palms of the hands and soles of the feet. This condition is caused by overactivity of the nerves that carry messages to the affected sweat glands. These nerves are part of the 'sympathetic' nervous system, which means that they are 'involuntary' or not under our conscious control.

Treatment may be with medication or, for underarm and palm sweating, may involve a surgical procedure known as Endoscopic Thoracic Sympathectomy (ETS). This is a minimally invasive procedure (it does not require a large incision or cut to be made) and involves interrupting the nerves that supply the sweat glands.