Dark blood 4 hours after tooth extraction may be normal or abnormal, such as self-coagulation dysfunction. The wound will bleed after tooth extraction, and as your own coagulation function works, the bleeding will gradually stop to form a blood clot to close the wound. As iron ions oxidize, the clot turns black. It may be discharged when spitting, which is normal. If the amount of bleeding is large, or the pain is severe, this is an abnormal situation, which may be due to the wound cracking or its own coagulation dysfunction. When there is black blood after 4 hours of tooth extraction, it is recommended to consult a doctor in time, follow the doctor’s instructions to carry out relevant examinations, clarify the cause with the help of the doctor, and carry out targeted treatment or therapy.