Allergic purpura is an allergic disease with capillary vasculitis as the main lesion, involving the skin most commonly, followed by the gastrointestinal tract, joints and kidneys, with an acute onset and variable symptoms. The disease is more common in children over 3 years of age, especially in school-age children, and is about twice as common in males as in females. The onset of the disease is usually preceded by a history of upper respiratory tract infection one to three weeks prior to the onset of the disease, and most often occurs in the spring and fall. The disease responds well to hormone therapy, except for kidney involvement. The duration of the disease is mostly about 1 month, occasionally prolonged, but the relapse rate is high, about 30% of patients have a tendency to relapse. Second, the cause According to research, allergic purpura and the affected children’s allergic constitution related. Bacteria attached to dust, seafood food, animal fur, cold air, pollen and drugs containing antibiotics and other ingredients can cause purpura attacks. Some studies have found that allergic foods such as freshwater fish, crab, milk and eggs are the most common, followed by beans and cereals. The general causes include: 1, infection: such as pediatric colds, tonsillitis, pneumonia, diarrhea, urinary tract infections, skin sores, etc. About half of the sick children have a history of upper respiratory tract infection 1-3 weeks before the onset of the disease. 2, food: such as fish, shrimp, eggs, milk, wine, drinks, soy products, leeks, beef jerky, etc., can cause the onset of allergic purpura, or make those who have been treated to improve relapse. 3, drugs: such as penicillin, sulfonamides, biological agents, various preventive injections, plasma products, blood, etc. 4, toxins: such as bee, snake, scorpion, mosquito bites, etc., may also cause the onset. 5, certain foreign substances: such as pollen, willow, pet fur, as well as paint, gasoline, dust, chemicals, pesticides, chemical fibers, etc., the affected children can develop the disease because of contact. The first thing that children or parents see is usually skin purpura, mostly starts to appear in bilateral calves, around the ankles, sometimes accompanied by hives, the more serious children can also appear bleeding spots on the upper limbs, chest and back, and even a large petechiae or bloody blisters. Purpura is characterized by bleeding spots that are high on the skin, varying in size, purplish in color, and do not fade when pressed. They usually subside in 1 to 2 weeks, but may recur or persist for weeks or months. Next is abdominal pain, which can be dull, vague or paroxysmal colic, with variable location and tender abdominal muscles, and may be accompanied by vomiting and bloody stools. There is also joint pain, about 1/3 to 2/3 of the children will have painful red and swollen joints and cannot walk. It is mostly seen in the ankle and knee joints, and some children even develop joint cavity effusion. Joint swelling is characterized by no sequelae after it subsides. In about 30% of children, renal damage, such as hematuria, proteinuria or tubuluria, may occur. This more severe manifestation is called purpura nephritis and usually occurs 2 to 4 weeks after the onset of the disease. The onset of nephritis varies from mild to severe, most of them are mild and usually do not cure themselves, a few can develop renal failure and uremia. Therefore, children allergic purpura once diagnosed must be treated in time. If you find a bleeding spot on your child, you should choose to go to a regular hospital for consultation and treatment. For pediatric allergic purpura, anti-allergic drugs, application of immunosuppressants, etc. are currently used; if there is an infection, antimicrobial agents will also be used: for abdominal pain, 654-2, TEGM or hormone treatment; for joint pain, symptomatic treatment such as pain relief is given. The aim is to reduce capillary exudation, relieve allergic symptoms and minimize the risk of complications. V. Prevention (1) Pay attention to avoid contact with pathogenic agents, such as pollen, chemicals, paint, gasoline, dust mites, etc. (2) Allergic children should not keep pets and minimize contact with animal fur, especially for children with clear allergens. (3) Pay attention to dietary hygiene, wash hands regularly, do not eat unclean fruits and vegetables and aquatic plants to eliminate the chance of intestinal parasitic infections. Avoid eating spicy food and stimulating food, seafood, etc. (4) Strengthen exercise, enhance physical fitness, improve the body’s immunity to various infections, avoid the triggers for the occurrence of allergic purpura. (5) Pay attention to climate change, prevent cold and keep warm, prevent cold and flu, room ventilation regularly to keep the indoor air fresh. (6) Before the disease is cured, do not vaccinate various preventive vaccines, must be cured 3 to 6 months before vaccination, otherwise it may lead to the recurrence of the disease.