Hello, Welcome to HCM Warfarin is an oral anticoagulant.This medication is used to treat blood clots (such as in deep vein thrombosis-DVT or pulmonary embolus-PE) and also to prevent new clots from forming in your body. Since you are giving history of blood clot in your lung,do not to stop the drug without your doctors advice.It may be quite dangerous. Although its a very good drug,it is not free of side effects like bleeding,osteoporosis so on.You can be free of this side effects by getting your blood tests (INR) done at regular intervals. Some foods can affect how warfarin works in your body and may affect your treatment and dose. So,avoid intake of foods such as broccoli, cauliflower, cabbage, brussels, sprouts, kale, spinach, and other green leafy vegetables, and certain vitamin supplements which are rich in vitamin K.