Hyperhidrosis is a skin disorder characterized by excessive sweating that often causes significant impairment in social, occupational, and emotional wellbeing. Hyperhidrosis is thought to affect 2.8% of the US population and can be of primary or secondary origin. Primary hyperhidrosis is usually bilateral, symmetric, and focal. The most common focal sites include, but are not limited to, the palms, soles, and axillae. Secondary hyperhidrosis is usually caused by an underlying medical condition or medication. Secondary hyperhidrosis must be ruled out before a diagnosis of primary hyperhidrosis is made.

Keywords

Hyperhidrosis

Primary hyperhidrosis

Secondary hyperhidrosis

Prevalence

Diagnosis

Key points

Introduction

Hyperhidrosis is a skin disorder characterized by sweating in excess of what is required for thermoregulation. Hyperhidrosis can be primary or secondary in nature and may have general, regional, or focal manifestations.1 Primary hyperhidrosis is most often focal and generally causes idiopathic, symmetrically bilateral excessive sweating of the axillae, palms, soles, or craniofacial region.2,3 Secondary hyperhidrosis manifests most often as generalized excessive sweating that is related to an underlying medical condition or use of medication. Hyperhidrosis results in a decrease in quality of life, may cause impairment in the ability to carry out daily functions, and in some cases may increase risk of cutaneous infection.4,5 Previous reports indicate that this condition affects 7.8 million people in the United States but this number may be conservative, because hyperhidrosis is both underreported by patients and underdiagnosed by health care professionals.2 Understanding the epidemiology of the disorder is critical for screening, diagnosis, and treatment.

Primary hyperhidrosis

Primary focal hyperhidrosis is excessive sweating in a specific region of the body that is not caused by other medical conditions or medications.2 The cause of primary hyperhidrosis is not well understood, but is thought to be due to an overactivity of the autonomic nervous system. Eccrine sweat glands, which are located in the deep dermal layer of the skin, are innervated by post-ganglionic sympathetic nerve fibers and are stimulated by the neurotransmitter acetylcholine.6 In primary hyperhidrosis, it is believed that these sweat glands receive aberrant stimulation by the sympathetic fibers causing excessive sweat production, although this has not been proved. Histologic evaluation of the affected areas demonstrates normal appearing eccrine sweat glands with a normal number, size, and density of the glands. Quantity and function of acetylcholinesterase is also known to be normal, indicating an overabundance of neurotransmitter is not the cause.3,6–8