The cause of allergic purpura is still unclear, and it is currently believed to be related to food, drug factors, infectious factors and so on. 1. Food: mainly animal heterogeneous protein caused by body allergy, such as eggs, seafood, milk and so on. 2. Drug factors: for people who use antibiotics such as penicillin, ibuprofen, indomethacin and other non-steroidal anti-inflammatory drugs, may lead to the occurrence of allergic purpura. 3. Infectious factors: for patients with combined infections of hemolytic streptococcus, measles virus, varicella-zoster virus, roundworms and other pathogens, it is also possible to cause allergic purpura. For allergic purpura patients, once diagnosed, should be actively treated under the guidance of the doctor, so as to avoid recurrence or aggravation of the disease.