A bag in the armpit hurts when pressed is most likely an enlarged lymph node in the armpit, which needs oral or intravenous antibiotic medication (such as cefradine); it may also be an epidermoid cyst, which needs to be surgically removed in the hospital; or it may be a boil, which can be treated with topical medication. 1. Swollen lymph nodes: Swollen lymph nodes in the armpit are usually caused by bacterial infection, and need to be treated with oral antibiotic drugs, such as cefixime and cefradine. After treatment, the pain can be relieved and the swelling of lymph nodes will gradually subside. Adverse reactions such as nausea and vomiting may occur during the medication, and it is forbidden for patients who are allergic to cefixime. 2. Epidermoid cysts: When epidermoid cysts appear in the armpit, pain symptoms may also occur, and then you need to go to the hospital to do lumpectomy to remove the cysts, and take good care of the cysts after the operation. 3. Boil: Boil is an acute purulent inflammation of the deep part of the hair follicle and surrounding tissues, often induced by Staphylococcus aureus. The skin lesions at the beginning of the follicular inflammatory papules, basal infiltration is obvious, after the expansion of inflammation to the surrounding area, the formation of hard nodules, accompanied by redness, swelling and heat pain, early boils are not suppurative can be used externally with 20% of the ichthyolite ointment, can also be used externally with mupirocin ointment. The reason why there is a bag in the armpit hurts when pressed is more, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease and follow the doctor’s instructions for symptomatic treatment.