Small red lump in the armpit

Redness and tenderness commonly occur with an inflamed hair follicle, boil, blocked sweat gland, cyst, shaving irritation, or a small skin infection. A swollen lymph node can follow an infection in the arm, breast, or nearby skin. [Breast Cancer](/conditions/breast-cancer/) and [Lymphoma](/conditions/lymphoma/) can present with an armpit lump, but a red lump does not by itself identify either condition. A clinician uses the skin appearance, tenderness, depth, mobility, duration, and other symptoms to decide whether testing is needed.

Keep the area clean and dry, pause shaving and fragranced products, and avoid squeezing or puncturing the lump. A warm, clean compress may ease discomfort if the skin is intact. Arrange a medical appointment if the lump does not settle, returns repeatedly, enlarges, feels deep or firm, or has no obvious skin cause. Tell the clinician about recent infections, vaccines, wounds on the arm, breast changes, and medicines. They may examine the breast, arm, and lymph nodes and decide whether imaging or a sample is appropriate.

Seek same-day care for spreading redness, severe pain, pus, red streaks, fever, chills, or feeling unwell. Get urgent help if swelling interferes with arm movement or breathing, or if it increases quickly. Arrange prompt review for a hard or fixed lump, a lump that persists after the skin redness improves, unexplained weight loss, drenching night sweats, or a new breast change.

Ask whether the lump is in the skin or a lymph node, what may have triggered it, and whether it needs drainage, medicine, imaging, or observation. Ask how to care for the skin, when to return, and which changes should prompt urgent contact.