Infant armpit redness need to identify the cause, may be physiological, may also be pathological; physiological causes need to adjust the lifestyle, pathologically caused by the need for targeted treatment under the guidance of a doctor, such as drug therapy. 1. Physiological: caused by sweat stimulation, if the long-term impregnation by some sweat, parents care is not in place, it may cause armpit redness. Parents need to pay attention to the local parts of the armpit when bathing children, the armpit itself exists in the sweat glands, and there are folds in the skin, when bathing the upper limbs need to be lifted up, the skin folds of the sweat stains as well as the local skin cleaned. 2. Pathologic: (1) Inter-abrasive rash, caused by local airlessness and friction, occurs in the armpits, neck and groin, the lesions are initially well-defined erythema, swelling is obvious, followed by vesiculation and oozing. Localized erythema without skin breakage, can be used externally as appropriate, such as glycerin lotion. (2) Prickly heat, is a small papule and blister that occurs rapidly when the sweat pore is blocked in a hot and humid environment. Generally, prickly heat will disappear soon after the skin is cooled down and dried out, and no special medication is needed. There may be other factors, redness is obvious, if the adjustment of lifestyle is not obvious, we should go to the hospital in a timely manner to clarify the cause of the disease, in accordance with the doctor’s instructions for standardized treatment, parents should not blindly give the child medication.