UV allergy, clinically known as photodermatitis, is a physical dermatosis, a phototoxic skin inflammatory reaction disease caused by the action of UV light on human skin. Some patients with the symptoms may be related to genetic factors, but also may be related to personal factors, food factors, drug factors, environmental factors, etc. Patients can appear erythema, papules, papules, self-conscious burning, stinging or itching, can be treated by means of personal protection, local medication, systemic medication, etc. I. Causes: 1, personal factors: itself is sensitive skin, the use of cosmetics is not suitable for personal skin type, or due to work reasons need to be exposed to the outdoors for a longer period of time, thus making the skin in a sensitive state; 2, food factors: caused by excessive intake or exposure to food containing photosensitive substances, common food containing photosensitive substances are celery, lettuce, figs, amaranth, etc.; 3, drugs Factors: such as contraceptive pills, penicillin drug reactions can cause skin allergies, which can induce ultraviolet allergy; 4, environmental factors: abnormal changes in environmental temperature, hot and cold, or the environment has allergenic pollen, dust, etc., is also one of the causes of ultraviolet allergy. Treatment: 1. Personal protection: In daily life, it is necessary to eliminate factors that cause skin allergy, pay attention to avoid sunlight and ultraviolet radiation, develop habits of light prevention and avoidance, pay attention to good sun protection measures when going out, you can play umbrella, wear sun hat, wear long-sleeved clothes, apply sunscreen, etc. Also avoid contact with allergenic substances; 2. Local medication: When rashes appear on exposed areas such as face or hands and feet, you can If the rash appears on the face or hands and feet, you can use tacrolimus ointment or zinc oxide ointment to relieve the symptoms. When local swelling occurs, local wet and cold compresses such as saline or boric acid solution can be applied; 3. Systemic medication: For more serious allergic reactions, it is recommended to consult a doctor promptly and choose antihistamines such as loratadine and benadryl for treatment under the guidance of a doctor. In case of edema, diuretics such as furosemide, captopril, etc. can be used as an adjunct to treatment. In case of co-infection, antibiotics should be actively administered for anti-infection treatment.