anhidrosis

Anhidrosis is a medical condition characterized by an absent or markedly reduced ability to sweat in response to heat or physical activity. It can involve the entire body (generalized anhidrosis) or only certain areas of skin (focal or localized anhidrosis). The term hypohidrosis refers to reduced sweating that is not completely absent. Normal sweating depends on the autonomic nervous system controlling eccrine sweat glands; disruption of nerves, glands, or signaling pathways can lead to anhidrosis.

Symptoms and risks include heat intolerance, rapid onset of overheating, dizziness or fainting, fatigue, and dry, flushed skin. In generalized cases, overheating can progress to heat-related illness or heat stroke, especially in hot environments or during exercise. Localized anhidrosis may be noticed as dry patches with little or no sweating.

Causes are varied and include congenital conditions such as hypohidrotic ectodermal dysplasia, where sweat glands are underdeveloped or absent. Acquired causes include autonomic neuropathies (for example, diabetic autonomic neuropathy), autoimmune autonomic disorders, skin injuries or burns that damage sweat glands, infections affecting the autonomic nerves, and medications with anticholinergic or sympathetic-suppressing effects.

Diagnosis relies on medical history, physical examination, and specialized tests of sudomotor function, such as thermoregulatory sweat tests and quantitative sudomotor axon reflex tests. Skin biopsy can assess the number and integrity of sweat glands in some cases.

Treatment focuses on preventing overheating and addressing underlying conditions. Management may include environmental cooling, hydration, gradual acclimatization to heat, and treating any identifiable cause when possible. There is no universal cure for anhidrosis, and prognosis depends on the underlying etiology.