The common causes of pain next to the armpit are the following: a. Young female patients often experience hyperplasia and congestion of the breast glands due to the exuberant estrogen levels in their bodies. This can cause hyperplastic pain in the breast and induce swelling and discomfort next to the armpit. Reducing the intake of greasy, spicy and stimulating foods and regular rest and rest time will help maintain the stability of the body’s hormone levels, thus reducing the symptoms of breast enlargement and pain in the axillary area. Secondly, due to malignant tumor of breast, causing axillary lymph node invasion in elderly female patients, it will cause cancerous pain next to the axilla, and patients can feel obvious harder lumps in the axilla. Patients are suggested to have breast malignant tumor excision plus lymph node dissection as soon as possible.