Those who have had a pulmonary embolism generally do not need to take warfarin all the time, but may need to take it all the time for recurrent venous thrombosis in patients who have risk factors that persist for a long time. Pulmonary embolism is a pathological and clinical condition caused by the entry of embedded material into the pulmonary arteries and their branches, blocking the blood supply to the tissues. Anticoagulants are needed later to prevent recurrence and further expansion of the thrombus. Warfarin is a commonly used anticoagulant and usually does not need to be taken all the time; oral administration for 3 to 6 months is sufficient. However, for recurrent venous thrombosis in patients with long standing risk factors, it can be taken orally for up to 12 months or even all the time. Warfarin adverse reactions can be petechiae, purpura, bleeding gums, nosebleeds, etc., so pregnancy, hemophilia, thrombocytopenic purpura and other bleeding tendency disease patients are prohibited. It is recommended that patients standardize the use of medication under the guidance of a doctor, do not self-medication, so as not to cause adverse reactions, if the body is not feeling well, timely medical treatment.