Hypohidrosis

Hypohidrosis is a reduced ability to sweat, resulting from a decreased number or impaired function of eccrine sweat glands or from dysfunctional sympathetic cholinergic innervation. It can be focal or generalized and may be present from birth or develop later in life. As a result, evaporative cooling is impaired, increasing the risk of overheating in hot or humid environments.

Clinical features include reduced or absent sweating in affected areas, heat intolerance, overheating, and dry or flaky skin. In milder cases, symptoms may be limited to visual signs of reduced sweating during heat exposure; more extensive forms raise the risk of fever and heat-related illness.

Causes are diverse. Congenital forms include hypohidrotic ectodermal dysplasia, often due to mutations affecting sweat gland development. Acquired hypohidrosis can arise from autoimmune or neuropathic conditions (such as diabetes with autonomic neuropathy), infections, skin or nerve injury, radiation, or medications with anticholinergic effects. Localized hypohidrosis can occur after botulinum toxin injections or laser treatment.

Diagnosis relies on history and physical examination, supplemented by sweat testing. The Minor starch-iodine test maps regional sweating, while quantitative tests such as thermoregulatory sweat testing (TTST) or QSART assess overall sweat function and innervation. Additional workup targets potential underlying causes when indicated.

Management focuses on avoiding overheating and addressing the underlying cause. Strategies include environmental cooling, hydration, skin care, and reviewing medications that reduce sweating. There is no cure for congenital forms; management is supportive and preventative.

Prognosis varies with extent and cause. Generalized hypohidrosis carries a higher risk of heat-related illness, whereas localized forms tend to have a more limited impact.