Bruising on warfarin may be caused by abnormal coagulation indexes, and it is necessary to go to the hospital to review the coagulation indexes and adjust the dosage of the drug. Warfarin belongs to the anticoagulant, mainly used for the prevention and treatment of thrombosis, but overdose of the drug can easily lead to bleeding, there can be subcutaneous bruising, mucous membrane bleeding and so on. And warfarin need to go to the hospital regularly to recheck the prothrombin time (PT) and international normalized ratio (INR) during the medication. If bruises appear on the body, or red urine, black stool, nasal gum bleeding, etc., go to the hospital as soon as possible, through the blood test PT and INR, to determine whether it is caused by drug overdose.INR index is recommended to be controlled between 1.8~2.5, if the index is too high easy to bleed, you need to increase the dosage of the drug, and the index is too low can not achieve the expected therapeutic effect, you need to increase the dosage of the drug. Specific medication needs to follow the doctor’s instructions. During the period of taking warfarin, you should eat less grapefruit, mango, these foods are easy to enhance the efficacy of warfarin.