A certain amount of blood can be swallowed in the saliva after tooth extraction, and every patient will involuntarily enter a part of blood in the digestive tract after tooth extraction, because no patient has been seen who can spit out all the blood. Generally, there will be slow bleeding half an hour after tooth extraction, and it is recommended to press a cotton ball or cotton roll in the wound area of tooth extraction and ask the patient to bite down tightly to stop the bleeding, and the bleeding will be gradually relieved after half an hour. However, it is normal to have blood in the mouth within 24 hours after tooth extraction, and most of the blood is swallowed by the patient, so this is a very normal physiological phenomenon and there is no need to worry.