The armpit pain is commonly caused by the following reasons: 1, hair follicle infection, when the local soft tissue infection will cause pain, usually combined with mild redness and swelling or even exudation, you can apply local iodophor, along with oral cephalosporin antibiotics, if necessary, you can also take oral medication to clear heat and fire, such as Shuanghuanglian oral liquid, etc. 2, may be caused by costochondritis, when the body suffered trauma or by The pain may be caused by a cyst in the sebaceous gland or even a malignant tumor in the lymph nodes. In short, if the pain persists, you need to go to the hospital in time to clarify the cause.