When patients first start taking warfarin, the dose adjustment of warfarin should be based not only on the measured value of INR, but also on the trend of INR changes. Generally, on the 5th day after warfarin application, if the INR has a tendency to increase, but has not yet reached the lower limit of the therapeutic target, attention should be paid, and if necessary, the dose needs to be reduced. It should be noted that the INR does not change until several days after warfarin dose adjustment, so dose adjustment should not be too frequent. If the INR of a patient taking warfarin for a long period of time is measured several times the result lies steadily outside the target range. Patients with high INR fluctuations are most likely to have thromboembolism or bleeding complications, and these patients should be reminded to pay attention to the diet These patients should be reminded to maintain a stable intake of vitamin K, take their medication as prescribed, and monitor their INR regularly. If a patient taking warfarin has had a recent fluctuation in INR, below the target range of 0.2 or above the target range of 0.4, the reasons for INR fluctuations should be sought, including: laboratory measurement errors, failure to take medication as prescribed, temporary application of medication that interacts with warfarin, a large fluctuation in dietary intake of vitamin K or a change in health status. If the cause of INR fluctuation is not found, the warfarin dose should be changed and the INR should be readjusted, and the measurement should be repeated within 2 weeks. Warfarin dose adjustment is based on the magnitude of the INR deviation from the target range and the patient’s previous response to warfarin dose adjustment. In most cases warfarin is increased or decreased by 5% to 20%. Excessive changes, such as more than 1/3 of the original dose, may be overkill in the INR. What’s more, patients should be reminded to always adjust the dose under the supervision of a physician when starting warfarin, because warfarin can vary in anticoagulant strength between people or even in different states of the same person, increasing the risk of complications if patients adjust the dose themselves.