Warfarin is currently the most widely used oral anticoagulant in the world and is often used to treat or prevent thrombotic disorders such as post-valve replacement, atrial fibrillation, lower extremity venous thrombosis and pulmonary embolism. Warfarin is a double-edged sword that can prevent and treat disease when used properly, but can lead to serious and even life-threatening consequences such as cerebral hemorrhage and gastrointestinal hemorrhage if used improperly. Many prescription or over-the-counter medications can enhance or diminish the effects of warfarin. It is important for patients taking warfarin for a long time to be aware of this, so that improper use does not lead to an increased risk of bleeding or thrombotic events. So, which drugs can affect the anticoagulant effect of warfarin? Herbs that reduce the anticoagulant effect of warfarin include: ginseng, American ginseng, and St. John’s wort. Western drugs that reduce the anticoagulant effect of warfarin include: phenytoin sodium, barbiturates, oral contraceptives, estrogen, clofentezine, rifampin, vitamin K, chlorothiazide, spironolactone, corticosteroids, etc. In addition to drugs, daily diet can also play a role in the effectiveness of warfarin: for example, spinach, cabbage, leek, coriander, lettuce, celery, watercress, carrot, tomato, broccoli, cauliflower, cabbage, lettuce, green pepper, chili, garlic, onion, egg yolk, soybean oil, cod liver oil, seaweed, avocado, animal liver, black tea, green tea. All are foods that can weaken the anticoagulant effect of warfarin. During the medication must pay attention to the following matters: 1. It is advisable to take the medication regularly. Patients need to take it at the same time every day. If you forget to take the medication, within 4 hours to make up; more than 4 hours do not make up, the next day normal medication, do not take a double dose. 2. It is advisable to check regularly. The dose of warfarin varies from person to person, and the dose of the drug should be adjusted according to the coagulation index. 3.It is advisable to have a regular diet. The mechanism of action of warfarin is to antagonize vitamin K to play the anticoagulant effect. The vitamin K content in various foods is different, so changes in diet structure will affect the effect of warfarin. Vegetables rich in vitamin K, such as spinach, asparagus, green cauliflower and lettuce, may reduce the anticoagulant effect of warfarin. Therefore, you should try to maintain a balanced diet structure, no need to deliberately favor or fast a certain food, do not blindly change the food structure, add nutrients. 4, pay attention to drug interactions. Warfarin’s anticoagulant effect is susceptible to drug interference, common antibiotics such as metronidazole, azithromycin, cefoperazone, levofloxacin, etc. will interfere with warfarin metabolism and enhance its anticoagulant effect. Phenytoin sodium and oral contraceptives, on the other hand, may reduce their anticoagulant effect. Therefore, it is important to inform the physician that you are taking warfarin, pay attention to drug-drug interactions, and monitor the INR when adjusting drug therapy, and adjust the warfarin dose if necessary. For patients who are taking warfarin for other diseases requiring surgical treatment, the drug should be discontinued before surgery after physician evaluation, usually 5-7 days in advance, and other anticoagulants with short duration of action should be used instead of warfarin, such as common heparin or low molecular heparin, etc. 5, pay attention to bleeding and other adverse reactions. The biggest adverse reaction of warfarin is to cause bleeding, during the drug must pay attention to whether there is skin mucous membrane bleeding, conjunctival bleeding, gum bleeding, nasal bleeding and black stool, hematuria and other conditions.