Eccrine glands are uniquely susceptible to a variety of pathologic pro
cesses. Alteration in the rate of sweat secretion manifests as hypohid
rosis and hyperhidrosis. Obstruction of the eccrine duct leads to mili
aria. The excretion of drugs into eccrine sweat may be a contributory
factor in neutrophilic eccrine hidradenitis (NEH), syringosquamous met
aplasia (SSM), coma bulla, and erythema multiforme (EM). Alterations i
n the electrolyte composition of eccrine sweat can be observed in seve
ral systemic diseases, most notably cystic fibrosis. This article summ
arizes current knowledge of eccrine gland pathophysiology.