Introduction

Hyperhidrosis may generally be defined as excessive sweating or sweating beyond physiological needs. It may be divided into generalized, regional and localized/focal types and, according to whether the cause is known or not, into primary/idiopathic and secondary forms. Secondary hyperhidrosis can be induced by a number of infectious, endocrine, metabolic, cardiovascular, neurological, psychiatric and malignant conditions; it can also be caused by certain drugs and poisoning. The prevalence of hyperhidrosis in the US population has been calculated at 2.8% (Strutton et al., 2004). Of those, primary axillary hyperhidrosis appears to be the most frequent type, severely affecting 0.5%.

Box 22.1 gives the diagnosis of primary focal hyperhidrosis set out by a multispecialty working group (Hornberger et al., 2004). It usually starts in childhood or adolescence and mainly involves the armpits, palms, soles and craniofacial region, either alone or in various combinations. There are well-known, particularly emotional, triggers of sweating episodes, but the exact pathogenesis of the sympathetic overstimulation of eccrine sweat glands is still poorly understood apart from a clear genetic background.