HERBAL MEDICINES OR DIETARY SUPPLEMENTS AND WARFARIN AND OTHER ORAL ANTICOAGULANTS - GLUCOSAMINE +/- CHONDROITIN

A couple of reports suggest that glucosamine with or without chondroitin may increase the INR in patients taking warfarin. In contrast, one case of a decreased INR has been reported when glucosamine was taken with acenocoumarol.
There do not appear to have been any controlled studies of this interaction. The cases described suggest it would be prudent to monitor the INR more closely if glucosamine is started. If a patient shows an unexpected change in INR, bear in mind the possibility of self-medication with supplements such as glucosamine.