Painful Armpit Cyst: When to See a Doctor

A large, painful cyst in the armpit (axilla) should be evaluated if you notice:

• Rapid growth or sudden appearance.
• Persistent or worsening pain beyond a few days.
• Signs of infection: Redness, warmth, swelling, pus drainage, red streaks.
• Fever or chills.
• Restricted arm movement due to size or location near nerves/vessels.
• No improvement with warm compresses and OTC pain relievers after several days.
• History of cancer or immunosuppression.

Common causes include infected epidermoid cysts, hidradenitis suppurativa, swollen lymph nodes, or abscesses. A clinician can drain, excise, or prescribe antibiotics as needed. Do not attempt to squeeze or lance it yourself.