The main characteristics of the early symptoms of allergic purpura are: first, the location, purpura is mostly seen on the extensor side of the lower limbs, buttocks and around the joints. The skin lesion is characterized as a bright red or dark red papule, erythema or patch that is high above the skin, slightly above the skin, or flat on the skin, with different size and shape, and is mostly symmetrical. Third, the time of appearance, mostly in batches. First, there may be a single rash, which gradually increases into a dense multiple rash. V. Accompanying symptoms, patients may have abdominal pain, vomiting, bloody stools and joint symptoms. Abnormal laboratory test results, platelet count, and bleeding and clotting time, are normal in most patients. If the bleeding time and clotting time are significantly shortened, another disease, thrombocytopenic purpura, is considered.