The main causes of purple bruises include trauma, drug reactions, and abnormal blood clotting. It is recommended that those who have more bruises that do not subside should seek medical treatment in time to avoid aggravating the condition and delaying treatment. 1. Trauma: When the body is traumatized by trauma, the subcutaneous blood vessels are squeezed to rupture and bleed, forming subcutaneous bruises, and the epidermis will appear bruises. 2. Drug reaction: due to long-term or overdose of certain drugs affecting blood clotting (such as warfarin, etc.), the capillaries around the body appear scattered bleeding points, the formation of purple bruises. When this happens, stop the medication immediately and consult the relevant doctor. 3. Abnormal coagulation function: Thrombocytopenia or thrombocytosis caused by disease will cause abnormal coagulation function and bruises appear on the body. At this time, it is recommended that people seek medical treatment.