odor, underarm

Excessive underarm (axillary) odor, or bromhidrosis, is caused by the breakdown of fatty acids and ammonia in the sweat from the apocrine¹ sweat glands of the underarm (axillary) areas of pubertal and postpubertal individuals. This breakdown is caused by bacteria on the skin. Antiperspirants containing aluminum chloride, zirconium, or zinc are helpful to reduce the amount of sweat, as well germicidal soaps or topical antibiotic creams such as gentamicin or cleomycin to reduce bacterial colonization.

Eccrine sweat glands simply secrete the clear watery fluid that relates to body cooling. Eccrine bromhidrosis is caused by bacterial breakdown of dead skin cells moistened by excessive eccrine sweating. An example of this type of bromhidrosis is "stinky feet." Aluminum chloride preparations (Drysol®) are helpful for this type of excessive sweating and resultant odor.

Theoretically, underarm odor should not be a problem in pre-pubertal children, since pubertal hormones produce the increase in fatty acid content of apocrine sweat that causes body odor. However, some prepubertal children become colonized with strains of bacteria that can cause offensive axillary odor, and these children respond to topical antibiotics, notably clindamycin.

1. Apocrine sweat contains part of the secreting cells (another type of apocrine secretion is breast milk). Apocrine sweat glands are located wherever there is body hair, but most densely in the axillary and pubic areas.

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