The causes of underarm soreness are as follows: 1, inflammation: infection near the armpit, swollen lymph nodes in the armpit, etc.; 2, soft tissue injury: soft tissues near the armpit, the armpit area of muscle tissue, soft tissue, sprain, trauma, etc. in the activities; 3, other: excessive fatigue in the armpit, localized redness, swelling, heat, pain stimulation, etc.. After the armpit soreness, the patient should consult the doctor in time, need to be examined, clear the exact cause of the cause of treatment. Before the diagnosis is confirmed, and before the formulation of a definite treatment plan, avoid the use of painkillers, in order to avoid covering up the condition and delaying the treatment.