underarms

The underarms, or axillae, are the pyramidal spaces located beneath the shoulder joints. Each axilla is bounded by the chest wall and latissimus dorsi on the back, the upper arm laterally, and the skin forming the axillary fold. The area contains skin, fat, lymph nodes, blood vessels, nerves, and muscles that attach to the upper limb, along with sweat glands and hair follicles.

The skin of the axilla often has a higher density of hair follicles and apocrine sweat glands, which become active at puberty. Eccrine glands are distributed widely and produce a watery sweat important for thermoregulation; apocrine glands secrete a thicker fluid that, when metabolized by skin bacteria, contributes to body odor. The axilla also houses a network of axillary lymph nodes that drain lymph from the upper limb, chest wall, and breast region.

Function and odor: Sweating helps regulate body temperature; odor mainly results from bacterial breakdown of secretions in the armpit. Hygiene plays a key role in managing odor and moisture.

Common conditions: Skin irritation, dermatitis, folliculitis, candidiasis, and hidradenitis suppurativa can affect the axilla. Hyperhidrosis is a condition characterized by excessive sweating. Infections or enlarging lymph nodes may signal other health issues and should be evaluated.

Care: Regular cleansing with mild soap, thorough drying, and use of deodorants or antiperspirants as desired. Hair removal is elective. Medical treatment is advised for persistent odor with fever, lumps, or persistent swelling, or for disabling sweating, which may include prescription antiperspirants, medications, or procedures.