Heparin is a very strong blood-thinning drug that is delivered by injection. If you receive heparin, make sure you check with your doctor before taking any type of supplement.
Chondroitin Based on chondroitin’s chemical similarity to the anticoagulant drug heparin, it has been suggested that chondroitin might have anticoagulant effects as well. There are no case reports of any problems relating to this, and studies suggest that chondroitin has at most a mild anticoagulant effect. 19 Nonetheless, prudence suggests that chondroitin should not be combined with heparin except under physician supervision.
Garlic The herb garlic (Allium sativum) is taken to lower cholesterol, among many other proposed uses. Because garlic has a blood-thinning effect itself, it might be dangerous to combine garlic with heparin. 1,2 Two cases have been reported in which the combination of garlic and the blood-thinner warfarin doubled the time it took for blood to clot. 3 Though warfarin thins the blood in a different way than heparin, there are concerns that garlic might interact similarly with heparin.