Allergic purpura, also called allergic purpura, is a kind of allergic capillary and fine blood vessel vasculitis, mainly manifested by purple-red petechiae and petechiae on the skin and mucous membrane, which will be accompanied by joint pain, abdominal pain and kidney damage in severe cases, and platelets will not be reduced in patients with allergic purpura. Platelet reduction can also cause purpura, however, in addition to the occurrence of purple spots on the skin, often accompanied by nosebleeds, gum bleeding, mucous membrane bleeding, internal bleeding, etc., bleeding time and clotting time are prolonged, you can go to the hospital to check the blood routine to see the number of platelets, you can identify which is the case. If it is allergic purpura, check the urine routine accordingly to exclude kidney damage.