In recent years, awareness of the dangers of deep vein thrombosis has increased and the clinical use of warfarin has grown. Because many drugs (including over-the-counter medications) as well as food can significantly affect the anticoagulant effect of warfarin, patients receiving warfarin therapy should avoid or minimize the combined use of medications. When it must be used, monitoring of coagulation should be intensified. Many prescription or over-the-counter medications can enhance or diminish the effects of warfarin. Clinicians and patients on warfarin therapy should be aware of this to avoid inappropriate use that may increase the risk of bleeding or thrombotic events. Drugs that enhance the anticoagulant effect of warfarin: aspirin, sodium salicylate, indomethacin, pautazone, quinine, diuretic acid, methylsulfonylurea, metronidazole, allopurinol, erythromycin, chloramphenicol, some aminoglycoside antibiotics, cephalosporins, cimetidine, clobetine, dextromethorphan, and p-acetaminophen. Drugs that reduce the anticoagulant effect of warfarin: phenytoin sodium, barbiturates, oral contraceptives, estrogens, clofentezine, rifampin, vitamin K, chlorothiazide, spironolactone, corticosteroids, etc. Drugs that cannot be combined with warfarin: epinephrine hydrochloride, amikacin, vitamin B12, meprobamate, indocin, chlorpromazine hydrochloride, vancomycin hydrochloride, etc. Some herbs (e.g. Salvia, Ginseng, Angelica, Ginkgo, etc.) enhance the anticoagulant effect of warfarin. Some foods (e.g. grapefruit, mango, garlic, ginger, onion, kelp, cauliflower, kale, carrot, kiwi, green peas, cabbage, leek, spinach, lettuce, grapefruit juice, cheese, egg yolk and animal offal) are rich in vitamin K, which can weaken the anticoagulant effect of warfarin and need to be taken into consideration during medication or consumption. Once a patient has taken the aforementioned medications or foods, he or she should consult a physician and decide whether to perform coagulation tests (mainly INR) or make the necessary interventions, as appropriate. We hope that all patients will take the medication correctly and review it in time to ensure the efficacy of the treatment.