Possible causes of sun exposure skin allergies include solar dermatitis, lupus erythematosus, etc., which can be improved by strengthening sun protection and medication. 1. Solar dermatitis: it may be due to allergy to ultraviolet rays, part of the patient’s skin in the excessive ultraviolet irradiation, the body’s photosensitive substances will be transformed from semi-antigen to complete antigen, causing the occurrence of light hypersensitivity reaction in the body, which leads to skin erythema, blisters, itching and other solar dermatitis manifestations. Such patients should pay attention to strengthen sun protection measures when they go out, and those with mild allergic symptoms can apply topical glycerine lotion, dexamethasone acetate ointment, tacrolimus ointment and other medications; those with severe allergic symptoms also need to take hydroxychloroquine, niacinamide, β-carotene, hydrocortisone, cyclosporine, and other medications to help with the treatment. 2. Lupus erythematosus: sunburn skin allergy may also be caused by lupus erythematosus, because in the sun, excessive ultraviolet radiation will induce some patients with lupus erythematosus activities, which aggravate the condition to a certain extent, resulting in patients with skin allergies or aggravation of the original skin inflammation. Such patients should pay attention to strengthening sun protection, avoiding excessive ultraviolet radiation, and actively treating lupus erythematosus, such as applying topical hydrocortisone cream, tacrolimus ointment, retinoic acid cream and other medications to help improve the symptoms of skin allergies; in severe cases, hydroxychloroquine, hydrocortisone and other medications need to be taken orally to help treat the disease. It is recommended that patients consult a doctor in time to identify the cause and use medication under the doctor’s guidance to avoid delaying the condition.