Pokrasnenie armpit brings discomfort, aches. to Postpone visit doctors is not appropriate. Formation under the muscle cavity may turn out to be dangerous disease. However often it is consequences frequent use antiperspirants with aluminum, non-compliance rules personal hygiene, excessive sweating. Redness triggers narrow blouse, infected razor-affiliation, the infection. lump under armpit hurts Discomfort under the arm, redness, lump getting warm? This is the abscess that should operated on, after that take medications. initial stage treat lotions, anti-inflammatory medicines. If the process switched to second stage, shown surgery.