Consider skin allergy, depending on the cause, the performance may vary, possible diseases are: papular urticaria, urticaria, solar dermatitis, contact dermatitis, drug rash, etc. 1, papular urticaria, also known as insect bite dermatitis, manifests as isolated or scattered, fusiform hard red papules with insect eyes at the top, some of which may have blistering manifestations, there may be a recent history of outings and bedding not frequently exposed to the sun leading to mite dermatitis and similar manifestations. 2, drug rash onset quickly, a large range, 4-20 days before the onset may have a history of drug use, and the use of drugs mostly for the first time. 3, sun dermatitis is mostly in the exposure area, and there may be a history of exposure to the sun before the onset. 4, skin care products dermatitis. 5, contact dermatitis. 6, allergic dermatitis and a large class of allergic dermatitis, according to the medical history to find a clear cause, can improve allergen testing to help screen, or treatment-based. All of the above diseases are manifested as itchy red bumps on the skin, and the initial diagnosis can be made with reference to the medical history and performance, and the treatment is largely based on removing the causative factors and anti-allergy treatment (oral cetirizine, topical dinaide ointment). In life, we should pay attention to not washing or scratching the affected area, not eating spicy and stimulating food, and not drinking alcohol.