The cause of allergic purpura is the feeling of external evil, diet disorder, blood stasis, deficiency of Qi and blood, clinical evidence of Yang, heat and actual evidence, if it is prolonged and repeated, it will be manifested as deficiency and mixed evidence of deficiency and actual. The first allergic purpura is caused by external evil, burning the blood, or even lead to heat and toxicity, forcing the blood to travel. If it does not heal for a long time, or repeatedly, then it will show the deficiency of qi and blood, stasis blocking the veins and ligaments, and become a difficult to treat disease. The allergic purpura is an autoimmune disease, caused by the body’s allergic reaction to certain allergic substances, resulting in increased capillary permeability and fragility, leading to bleeding and edema in subcutaneous tissues, mucous membranes and internal organs. Allergens can be caused by a variety of factors, but it is often difficult to find the exact cause for each specific case. Infections (including bacteria, viruses and especially parasites) are usually considered to be the most common cause, followed by allergic proteins in food (e.g., fish, shrimp, eggs, etc.) and other drugs (antibiotics, sulfonamides, antipyretics, sedatives, etc.), pollen, insect bites, vaccinations, etc. may be triggering factors for the disease.