Patients who take physician-prescribed blood thinners need to avoid several classes of medications, including cold medication, painkillers, herbal remedies, and certain drugs used to treat indigestion and a variety of stomach ailments, according to the Agency for Healthcare Research and Quality. Those taking blood thinners should also avoid aspirin.
Blood thinners interact with a variety of medications and common supplements, including vitamins and herbal remedies. Unless advised otherwise by a medical professional, those taking blood thinners should avoid taking these supplement and remedies when taking blood thinners, according to WebMD. Other drugs such as nonsteroidal anti-inflammatory drugs, ibuprofen, diclofenac, naproxen, celecoxib and salicylates possess anticoagulant properties, which heighten the risk of uncontrolled internal or external bleeding if taken with prescription blood thinners, according to WebMD and RXlist.com
Some herbal products such as green tea, ginseng, danshen, bromelains, fenugreek and garlic-based supplements also react with blood thinners such as warfarin, according to WebMD. Warfarin is a common blood thinner that interacts with a wide range of medicines, including anal and vaginal suppositories, increasing or decreasing the International Normalized Ratio, or INR, which is a measure of how quickly blood clots.
Vitamins such as Vitamin K can lower a patient's INR, increasing the risk of forming dangerous clots, according to the American Heart Association. Such a condition can cause complications in patients suffering from deep vein thrombosis, as WebMD reports.