Patients with allergic purpura may have neutrophilia and eosinophilia on routine blood tests. In patients with thrombocytopenic purpura, there may be a decrease in the number of platelets. Henochromic purpura belongs to a kind of vascular metamorphosis, and the disease is related to the body’s allergic reaction to a certain sensitizing substance, which is mainly manifested in the clinic as subcutaneous hemorrhagic spots. Blood tests may show an increase in the number of eosinophils, as well as an increase in the number of leukocytes or neutrophils. The blood test is not a sensitive test and does not confirm the diagnosis of purpura, but only serves as a means of exclusion, e.g., to exclude thrombocytopenic purpura. For those who are suspected to have allergic purpura, please consult the hospital in time, and actively diagnose and treat the disease to avoid delaying the condition.