Today over 15 million US citizens consuming herbal remedies and other potent supplements. This is a cause for worry, as an article in The Journal of the American College of Cardiology lists 25 popular herbal products that can interact with heart medication. While any positive effect is still yet to be documented for many of the remedies, the negative side effects might be very serious when combined with medications such as beta blockers, statins and blood thinners. The four main herb supplements to avoid while on blood thinners are : garlic, ginkgo, ginseng, and ginger . If on blood pressure or heart rythm medicine avoid St Johns worth (also called Hypericum). Grapefruit juice can increase the effect of medications, and lead to liver damage and muscle pain.
The best thing to do is to avoid all unnecessary supplements altogether, and to always inform your doctor if you plan on taking any.