If there are black stools, hematuria, large unexplained bruises, coffee-like vomit, nosebleeds or gum bleeding, or excessive menstruation in female patients, the patient should be seen promptly, the INR should be rechecked, and the amount of anticoagulant should be reduced under the guidance of the doctor. Pay attention to avoid trauma and other factors that cause bleeding in daily life, such as bleeding from skin incisions caused by shaving. Some drugs have antagonistic effect with warfarin and shorten the time of prothrombin, such as VitK, barbiturates, estrogen, oral contraceptives, etc. Patients should be instructed to pay attention to them in their daily life to ensure safety. Some drugs have synergistic effects with warfarin to prolong the prothrombin time, such as antipyretic analgesics, chloramphenicol, broad-spectrum antibiotics, long-acting sulfonamides, salicylates, etc. Therefore, the application of other drugs during anticoagulation must be taken under the guidance of a doctor. It is required to take the medication at the same time fixed every day with accurate dosage. Patients are instructed to time the alarm clock, send messages by pager, and send letters from family members to supervise, etc., so as not to forget, and if they forget to take it on one day, no additional dose should be taken the next day. The prothrombin time should be kept within 1.5 to 2.0 times the normal control value while taking warfarin. The anticoagulation monitoring protocol requires once every 2 weeks for the first 2 months after discharge, once every 2 to 3 weeks for 2 to 6 months, and once every 2 to 3 months after 6 months. All dental operations: routine scaling, extractions, fillings, operations on the gums and dental bed; any major surgery; some of the following minor operations: abscess drainage, tonsillectomy, appendectomy, prostate surgery, childbirth; operations that can cause trauma to the tissues of the body: bladder examinations, rectal and colon examinations, etc.