Most people have probably heard of the importance of sun protection in reducing chronic cumulative UV damage. However, many people may have a certain amount of luck: if you apply sunscreen less than once, you won’t get wrinkles or cancer right away, right? In fact, many people also suffer from another kind of sun damage, namely the short-term visible “solar dermatitis”. Clinical manifestations Seasonal onset: Spring and summer. Repeated attacks that last for years. Common population: Young and middle-aged women. There is a clear relationship with sun exposure: sun exposure can trigger it, and the condition can be relieved by avoiding light for a period of time. Trigger test can be clear: dosage was erythematous amount of medium-wave erythematous ultraviolet (UVB) irradiation of the same area, once a day, a total of 3 times, can induce the rash. Rash site: mostly seen in exposed areas, such as the face and neck, the V-zone of the forehead, the back of both hands and the extensor side of the forearm. Rash characteristics: The rash often occurs 30 minutes to a few hours after continuous sun exposure and is polymorphic such as erythema, papules, pemphigus, blisters, nodules, etc. Mossy lesions may also appear. The itching is obvious, mostly in about 7 days to subside, without leaving a scar. Prevention is the key 1. Sun protection is the prerequisite to avoid recurrence: such as wearing long-sleeved clothes, broad-brimmed hats, external sunscreen, etc. Apply sunscreen (such as SPF15 or 30/PA++) 15~20 minutes before going out, and avoid using photosensitive food or medicine. 2.Training the body’s ability to tolerate light exposure: gradually increase the amount of light exposure in winter and spring or in spring and summer, participate in outdoor activities on the principle of avoiding light, try to choose to receive small doses of short duration UV radiation before 9 a.m. and at 4 p.m., gradually increase the light brightness and improve the body’s ability to tolerate light exposure. Treatment 1, symptomatic treatment: oral antihistamines, such as cetirizine, loratadine, etc., the rash at the topical use of furnace glycolic lotion or corticosteroid cream. 2, other oral drugs: such as nicotinamide, hydroxychloroquine, thalidomide, severe cases can be short-term use of hormones such as prednisone.