Like many arthritis treatments, glucosamine (even when used without
chondroitin) may possibly have hematologic effects that could cause it
to interact with warfarin. However, the evidence is far from
conclusive. Below you'll find selected excerpts from web pages which
discuss the matter.
"An increase in the International Normalized Ratio (INR) was noted
when glucosamine was administered to patients receiving warfarin. INR
values decreased when glucosamine was stopped."
Arts en Apotheker
"Chondroitin and heparin, a drug used to thin the blood, are similar
in chemical composition. For this reason, some researchers speculate
that people may suffer bleeding complications from chondroitin,
particularly when it is used in combination with other blood-thinning
medications, such as aspirin, warfarin, or heparin. For people who are
taking blood-thinning medications, it is wise to first consult a
healthcare practitioner before trying chondroitin."
"Chondroitin sulfate... May increase the effects of anticoagulants /
blood thinning drugs & herbs heparin, warfarin/coumadin, aspirin)"
Hospital for Special Surgery
"The Arthritis Foundation does not currently recommend the use of
chondroitin. if chondroitin sulfate is taken, it could very well
interact with anticoagulants such as warfarin or heparin and cause
increased bleeding tendencies."
Howard University Hospital
On the other hand, there are reputable sources that indicate no
serious interaction between glucosamine and warfarin:
"Hematologic effects have been a concern. Chondroitin sulfate and
GAGPS have a heparinoid structure. Parenteral glycosaminoglycans can
prolong the prothrombin time, the partial thromboplastin time, and
decrease platelet aggregability. A number of trials noted no
significant effects on the complete blood count when oral glucosamine
or oral chondroitin sulfate were given separately. In dogs, the
combination oral preparation produced minor transient decreases in
hematocrit and white blood cell count; decreases in platelet count and
aggregability; but no change in bleeding or clotting times. Despite
statistical significance of some changes, values stayed within the
normal clinical range."
U.S. Navy Seals Oesteoarthritis tests
"There are no reports in the literature of an interaction between
glucosamine and warfarin. There is no particular reason why
glucosamine should interact with warfarin since it is not metabolised
by the cytochrome P450 system, but is instead broken down in general
metabolism via the carbohydrate pathways. The serum level of
glucosamine is very low even immediately following a dose, so a direct
interaction is also unlikely. Our in-house experience with glucosamine
adverse reactions has not (to date) involved a case of warfarin
sensitivity. Finally, in many clinical trials no such interaction has
been reported. Again, if in doubt it is recommended you consult with
you health care adviser."
Here you'll find a collection of links to articles which provide
information about glucosamine:
The Arthritis and Glucosamine Center
Search terms used:
"glucosamine" + "warfarin"
"glucosamine" + "coumadin"
"glucosamine" + "heparin"
"glucosamine" + "hematologic effects"
"glucosamine" + "blood thinner"
"glucosamine" + "anticoagulant"
"glucosamine" + "prothrombin"
"glucosamine" + "clotting"
"glucosamine" + "inr"
If you should decide to try glucosamine, I strongly recommend that you
tell your physician. He or she may want to monitor your International
Normalized Ratio (INR) to keep a close look at your prothrombin time.
I hope this helps! Please keep in mind that Google Answers is not a
source of authoritative medical assistance; the material I've
presented above is not intended as a diagnosis, nor as a substitute
for the services of a qualified medical professional.
If anything is unclear, or if a link does not function, please request
clarification; I'll gladly offer further assistance before you rate my