What should you know about a small itchy lump in the armpit?

Itching can occur when the skin is irritated by shaving, deodorant, friction, or contact dermatitis. A blocked hair follicle, boil, cyst, or local infection may feel tender or warm. Lymph nodes in the armpit can enlarge while the immune system responds to an infection or inflammation in the arm, chest, or nearby skin. Breast cancer and lymphoma can also present with an armpit lump, although a lump alone cannot identify its cause. Note whether it is in the skin or deeper, whether it moves, and whether the skin is red or draining.

Avoid squeezing, scratching, or repeatedly checking the area. Pause new deodorants and shaving until the skin settles, and keep it clean and dry. Record when you first noticed the lump, any recent skin injury, vaccination, infection, or breast change, and whether it is growing. Arrange a medical examination if it does not settle, returns, or feels deep. The clinician may inspect the skin, examine nearby areas, and decide whether imaging or a sample is needed.

Seek prompt medical care for a rapidly enlarging lump, spreading redness, marked warmth, pus, fever, or severe pain. Arrange an assessment for a hard or fixed lump, a lump that persists, or associated breast or nipple changes, unexplained weight loss, drenching night sweats, or ongoing fatigue. Seek urgent help if swelling is accompanied by breathing difficulty or you feel severely unwell.

Ask whether the lump appears to be in the skin or a lymph node, what features make infection more likely, and how long observation is reasonable. Ask whether your breast and arm should be examined, and what test would clarify the cause if the lump remains.