Itchy armpit rash may be contact dermatitis, eczema, ringworm and other skin diseases. (1) Contact dermatitis: contact dermatitis refers to the skin contact with certain sensitizing or irritating substances, causing an inflammatory reaction of the skin at the contact site or even outside the contact site, which causes itchy armpits with red rashes and pimples. (2) Eczema: the cause of eczema is still unclear, may be related to chronic infection, endocrine and metabolic factors, belongs to a chronic itchy skin disease, during the attack will appear skin erythema, papules, blisters, oozing, accompanied by intense itching of the skin. (3) Ringworm: usually associated with dermatophyte infection, may occur in any part of the body, such as armpits, can cause localized ring-shaped erythema accompanied by flaking, itching phenomenon. If you find itchy red rash in the armpit, you should consult a doctor in time, ask the doctor to specify the cause of the disease, and if necessary, carry out appropriate treatment.