Warfarin, which is frequently used in the treatment of thromboembolism, is a potent anticoagulant. It is a narrow therapeutic index drug and there is a risk of bleeding when the therapeutic dose is exceeded. It interacts with many drugs and foods. Due to drug and food interactions, the effectiveness of treatment decreases or spontaneous bleeding occurs. Although drug interactions constitute a small part of adverse drug reactions, they are important because they cause predictable and preventable mortality and morbidity. Prevention of drug interactions provides shortened hospital stay, reduced readmission rate, and reduced treatment costs. Examining the treatment applied to patients in terms of drug interactions increases the effectiveness and reliability of the treatment. The purpose of this review is to increase the knowledge level of warfarin on drug and food interactions.