Purpura is not contagious, purpura is a bleeding disorder that manifests itself in the skin as petechiae, petechiae. There are many causes of purpura, touch purpura is due to the patient’s thin skin or increased capillary fragility, resulting in petechiae and petechiae on the skin once there is a slight touch, this is mostly caused by taking glucocorticoids and other drugs. The most common representative disease of vascular purpura is allergic purpura, which is a systemic lesion due to infection or allergy induced immune abnormalities in the body. Platelet purpura is an idiopathic thrombocytopenic purpura that occurs due to a decrease in the number or abnormal function of platelets. After a patient develops purpura, the cause needs to be identified and then treated symptomatically.