Itchy armpits can be caused by friction, eczema or contact dermatitis. 1. local friction: armpit red itch, if it is presenting diffuse redness, accompanied by friction pain, may be caused by local friction, such as arm activities and sweat and clothing and other friction, resulting in local skin red itchy phenomenon. 2. skin eczema: armpit red itch if the local erythema and papules, may be the armpit eczema-like changes, there may be erosion, oozing, keratinization and other symptoms. 3. Contact dermatitis: If the patient is allergic, the skin in the armpit area is subjected to external stimuli, an inflammatory reaction may occur, resulting in localized red itchy symptoms. Red itchy armpits are recommended to actively go to the regular hospital, clear what causes, and then targeted treatment.