If your arms itch with small granules after sun exposure, it may be related to solar urticaria, and it is recommended to combine desensitization treatment with antihistamines and general preventive measures. Solar urticaria can appear in the exposed parts of the body after sunlight exposure, generally 1 to 2 hours to subside, can be accompanied by local itching and stinging. Solar urticaria need to take antihistamines such as loratadine, and can be combined with hydroxychloroquine, UVA or UVB desensitization therapy. Topical sun blockers can also be used to prevent solar urticaria. In addition, it is also necessary to minimize the prolonged sunlight activities, but can be moderate outdoor activities, conducive to the body to improve resistance. After the sun leads to localized itching and skin lesions, it is recommended to consult a doctor in a timely manner, in accordance with the doctor’s instructions on the cause of the symptomatic treatment. Drugs should be used according to medical advice.