Itching under the armpits may be related to physiological factors, or it may be caused by eczema, folliculitis, intertrigo and so on. 1. Physiological factors: especially in the hot summer, due to poor ventilation under the armpits, sweating more, resulting in prolonged stimulation of the skin by sweat, may cause itching under the armpits. 2. Eczema: due to a variety of internal and external factors stimulation caused by eczema, may cause itchy armpits, may also be accompanied by local skin erythema, papules, blisters, vesicles and oozing and other manifestations. 3. Folliculitis: due to poor hygiene or sweating under the armpits, under the stimulation of these undesirable factors, it is likely to cause folliculitis, which may lead to itchy under the armpits, and may be accompanied by localized papules, small pustules and other symptoms. 4. between friction rash: usually due to more sweat under the armpits, long time in the humid and warm environment, coupled with repeated friction stimulation, may cause itchy armpits under the armpits, may also be accompanied by localized skin erythema, oozing and other manifestations. Itchy under the armpits, but also for other reasons, in the exclusion of physiological factors, should be as soon as possible to see a doctor, clear reasons, give targeted treatment.