Swallowing blood water after tooth extraction is to prevent repeated mouth opening activities from affecting the pressure effect of cotton balls on the wound. Due to the tearing of soft tissues and rupture of small blood vessels during tooth extraction, some bloody exudate will be mixed in the saliva, and as the anesthetic effect gradually disappears and the patient feels painful in the wound, the doctor usually advises the patient to bite on the sterile cotton ball or gauze to compress the traumatized wound and blood vessels to stop the bleeding and pain. It is common to swallow blood after tooth extraction, not strictly in the sense of swallowing, but because if spitting out, it is necessary to open the mouth to move, when the cotton ball used to stop bleeding loosens, there is a possibility of increased bleeding and increased pain. Therefore, generally after tooth extraction, the doctor will recommend to bite the cotton ball tightly for about half an hour, or according to the patient’s own situation, to extend the compression time appropriately, during which the bloody exudate should be swallowed, not to open the mouth to spit, speak, eat, etc., and not to lick the gum wound frequently so as not to affect the wound healing. If excessive bleeding occurs, pain persists without relief, or bleeding persists even after half an hour of compression, consider local and systemic factors, such as infection occurring during the operation, poor postoperative wound healing, incomplete tissue cleanup, or low platelets on their own. If abnormalities occur, timely feedback to the doctor is required to clarify the cause of the abnormal condition as early as possible to avoid adverse consequences.