Medically reviewed by Kashif J. Piracha, MD Armpit pain can have many causes, ranging from injuries and irritants to ...

Painful armpit lumps are often due to a swollen axillary lymph node under the armpit. This is usually a sign that the body is fighting an infection, but it can sometimes indicate cancer.

Other causes of an armpit rash include a yeast infection, psoriasis, or seborrheic dermatitis. Rashes are pesky patches of irritated skin that can affect any part of your body, including your armpits.

Lymph nodes are part of the body’s immune system. A swollen lymph node in the armpit may be a sign of a bacterial or viral infection, an injury, or a serious health condition, such as cancer.