The human body contains between 2 and 4 million sweat glands, with the highest concentrations in the underarms, palms, and soles. In normal function, the sympathetic nervous system signals these eccrine glands to produce sweat in response to rising body temperature, physical exertion, or emotional stress. In hyperhidrosis, this signaling pathway becomes hyperactive, triggering sweat production without appropriate stimuli.
Primary focal hyperhidrosis, the most common form, is believed to result from overactivity in the sympathetic nervous system's cholinergic pathways. The neurotransmitter acetylcholine overstimulates sweat glands, causing them to produce perspiration at rates 4 to 5 times higher than normal. This dysfunction typically begins in adolescence and has a strong genetic component, with up to 65% of patients reporting a family history.
Secondary generalized hyperhidrosis can develop at any age and is associated with underlying medical conditions including thyroid disorders, diabetes, menopause, infections, or certain medications. Unlike primary hyperhidrosis, secondary forms tend to cause widespread sweating rather than affecting specific focal areas.
