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. Anyone can be affected at any site. Depending on the pathogenesis, the cause can be divided into primary irritants and contact sensitizers. (1) Common primary irritants are divided into: 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, ethanol amines, petroleum and coal tar, etc. 2, common contact allergens and their possible sources are dichromate, nickel sulfate, mercury dioxide and leather products, clothing jewelry, cement, etc. One particular type of contact dermatitis is skin sensitization that can be caused by cosmetics or hair dyes, poor diaper changes for infants, paints or volatile gases. 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.