Bruising that doesn’t go away may be related to purpura, coagulation disorders, and drug factors. 1. Purpura is caused by increased permeability and rupture of subcutaneous blood vessels that bleed due to various reasons. Since the blood is not drained out of the body, bruises are formed under the skin. Before the disease is effectively treated, the petechiae will persist and may even appear in other parts of the body. 2. Coagulation dysfunction refers to the lack of coagulation factors due to various reasons, which will not only be manifested as persistent petechiae, but also nosebleeds and bleeding gums and so on. 3. Drug factors mainly refers to the adverse effects of drugs leading to subcutaneous bleeding, such as long time taking aspirin and other anticoagulant drugs may lead to increased skin capillary fragility, bruising performance. Because of the many causes of subcutaneous bleeding, the specific circumstances need to ask the doctor for an interview and improve the relevant examination.