Solar dermatitis is a kind of acute injury skin reaction caused by excessive exposure to sunlight on the exposed parts of the skin, according to the different pathogenesis of its type is also different, there are common sunburn, phototoxic reaction and photosensitive reaction. 1. Sunburn: mostly caused by excessive sun exposure, the main mechanism is that the skin receives more than its tolerance to medium-wave ultraviolet radiation, thus causing acute skin inflammation. 2. Phototoxic reaction: It is a non-immune reaction that can occur in any individual who receives excessive sun exposure. It can be divided into acute and chronic, and the chronic ones are often seen in seafarers and other long-term repeated large amounts of sun exposure. 3. Photosensitive reaction: often occurs only in a few individuals with photosensitive body, its essence is a kind of lymphocyte-mediated delayed-type hypersensitivity reaction. Photosensitive substances absorb light energy and combine with macromolecules in the body to form antigens, thus stimulating the body to produce antibodies or cellular immunity and cause disease. If you feel unwell, it is recommended that you consult a doctor in time for diagnosis and treatment, and do not blindly use medication.