The CPSA gratefully acknowledges Zoë Phillips, MPH, MD candidate, University of Saskatchewan, and Gordon E. Searles, MD, FRCPC, FACP, for assistance in the preparation of this report. February 2021.

Hyperhidrosis is a condition characterized by excessive sweating. It is estimated to affect up to 5% of the population. Hyperhidrosis can occur over specific localized areas of the body (called focal areas), or over the entire body (called generalized).

There are two main categories of hyperhidrosis: primary and secondary. Primary hyperhidrosis tends to be focal in nature, whereas secondary hyperhidrosis more often presents as generalized sweating.

Primary focal hyperhidrosis: Primary focal hyperhidrosis commonly affects the underarms, soles of the feet, palms, and face and scalp, but can also involve other discrete areas of the body. It tends to It tends to be mirrored and on both sides of the body, and it is common for combinations of focal areas to be affected. It is not caused by any underlying medical disease or drug.

The cause of primary focal hyperhidrosis is not certain, but the tendency may be inherited. Eccrine sweat glands are one of three main types of sweat glands and help humans stay cool. They are located throughout the body, but exist in greatest quantity on the palms, soles, and underarms. There is no change in the number or size of the eccrine sweat glands in people with hyperhidrosis. Hyperhidrosis is instead thought to occur when there is overactivity of the thermoregulatory centre in the hypothalamus of the brain. This overactivity is then transmitted via the sympathetic nervous system to the eccrine sweat glands, which causes them to be overactive and produce more sweat.

Secondary hyperhidrosis: Secondary hyperhidrosis is less common than primary hyperhidrosis. It is most commonly generalized, but it can occur rarely in specific areas either equally mirrored on both sides of the body or on only one side of the body. Secondary hyperhidrosis is generally caused by an underlying condition. Causes for secondary hyperhidrosis include cancer, infection, endocrine/metabolic disorders, cardiovascular disease, respiratory disease, neurologic disorders, psychiatric disorders, or medications.