Contact dermatitis is an acute or chronic inflammatory reaction of the skin mucosa at the site of contact due to exposure to certain exogenous substances. It can occur at any site. According to the different pathogenesis, it is divided into primary irritant contact dermatitis and allergic contact dermatitis. Common primary irritants are divided into: 1, inorganic: sulfuric acid, nitric acid, hydrochloric acid, sodium hydroxide, sodium carbonate, calcium oxide, metal elements and their salts. 2. Organic: formic acid, acetic acid, phenol, ethanolamines, petroleum and coal tar, etc. Common contact allergens and their possible sources are: dichromate, nickel sulfate, mercury dioxide and leather products, clothing jewelry, cement, etc. Among the specific types of contact dermatitis include skin sensitization caused by cosmetics, hair dyes, infant diaper changes, paints or volatile gases, etc. Airborne chemical suspensions may also cause acute and chronic dermatitis at exposed sites. Sprays, perfumes, chemical dusts, and plant pollen may also be sources of sensitization in contact dermatitis. Treatment of contact dermatitis involves finding the cause, removing the exposure, and aggressive symptomatic management. After healing, try to avoid re-exposure to allergenic sources to avoid recurrence.