Allergic purpura is a capillary allergic hemorrhagic disease, more common, mostly self-limiting, is curable, but there is a possibility of recurrence. It is a capillary hemorrhage caused by allergic reaction of the body to certain substances. Clinical manifestations are: 1. skin: skin purpura is the first symptom, often symmetrically distributed, in severe cases skin necrosis or semi-ulcer formation; 2. abdomen: abdominal pain is seen in 50% of patients, in severe cases combined with vomiting and gastrointestinal bleeding; 3. joint symptoms. Mostly seen in large joints such as knee and ankle; 4, renal lesions: hematuria, proteinuria, edema, hypertension; 5, neurological symptoms and respiratory symptoms are rare. Treatment of allergic purpura should first stop contact with possible allergic substances, use antihistamines to counteract allergic reactions, use epinephrine for patients with arthralgia and abdominal pain, use immunosuppressants when combined with renal lesions, and anticoagulation therapy when acute nephritis occurs (please consult a specialist at a regular hospital for specific medication). If the disease is manifested only by skin and joint damage, the course of the disease is generally short, but if the abdominal symptoms are obvious, the course of the disease is longer. The disease can be cured and most of them have a good prognosis, but when exposed to allergens again, it can lead to recurrence of the disease. Multiple recurrences and progression to renal failure with nephritis are associated with a poor prognosis.