Contact dermatitis is an acute or chronic inflammatory reaction that occurs at the site of skin-mucosal contact due to exposure to certain exogenous substances. Contact dermatitis can be divided into acute, subacute and chronic according to the course of the disease, in addition to the existence of some etiology and clinical manifestations and other aspects with some special clinical types. 1, acute contact dermatitis: the onset of the disease is more acute. The lesions are mostly confined to the contact area, and a few can spread or involve peripheral areas. The shape of the lesion is related to the contact material, the boundary is clear, the affected area has papules and papules, in severe cases, the redness and swelling is obvious and blisters and blisters appear, patients often feel itching or burning pain, scratching can bring the pathogenic material to the distant parts and produce similar lesions. A small number of patients with severe disease have systemic symptoms. 2, subacute and chronic contact dermatitis: if the irritation of the contact material is weak or low concentration, the lesions can start subacute, manifesting as mild erythema, papules, unclear boundaries. Long-term repeated exposure can lead to chronic local lesions, manifested as mild hyperplasia and mossy lesions. 3. Special types of contact dermatitis: (1) Cosmetic dermatitis: dermatitis caused by contact with cosmetics or hair dyes. The disease varies in severity, the lighter for the contact area appears red, swollen, papules, papules, the heavier can appear on the basis of erythema blistering or even throughout the body. (2) Diaper dermatitis: diaper change is not diligent, resulting in bacterial irritation of the skin. Mostly involving the infant perineum, sometimes can spread to the groin and lower abdomen. The lesions are large and flushed, and may also appear as macules and papules with clear margins and a pattern consistent with the extent of diaper dressing. (3) Lacrimal dermatitis: skin sensitization caused by paints or volatile gases, mostly involving exposed areas. The manifestations are flushing, edema, papules, papules, blisters, and in severe cases, fusion into large blisters. Self-perceived itching or burning. (4) Airborne contact dermatitis: Airborne chemical suspensions may cause acute and chronic dermatitis in exposed areas, especially the upper eyelids and face. Treatment of contact dermatitis is to find the cause, remove the exposure and treat it symptomatically, and avoid re-exposure to the allergen to avoid recurrence.