Redness and itchiness of the skin when exposed to the sun is considered to be a solar dermatosis, which is related to sunburn, phototoxic reaction and photosensitivity reaction. 1. Sunburn: acute inflammation of the skin caused by ultraviolet rays in excess of the tolerated amount. 2. Phototoxic reaction: a kind of non-immune reaction, which occurs in any individual who receives excessive sunlight irradiation, and can be divided into acute and chronic, and the latter is mostly seen in people who receive large amounts of sunlight repeatedly over a long period of time, such as seafarer’s skin, actinic keratosis, and photodamage. 3. Photosensitive reaction: it is a kind of lymphocyte-mediated delayed hypersensitivity reaction, which only occurs in a few individuals with photosensitive qualities, and will stimulate the body to produce antibodies or immunity and thus cause solar urticaria, polymorphic sun rash and so on. Normally, sun exposure should be avoided, and physical shading agents should be applied to the exposed areas. Early treatment can also be carried out with topical glycerite lotion or glucocorticoid ointment, and antihistamine medication should be used if the itching is severe. The above situation, it is recommended to go to the hospital in a timely manner, the drug should be used in accordance with the doctor’s instructions, to avoid aggravation of the condition.