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Ask Dr. Gourmet

Does Vitamin C interact with Coumadin (warfarin)?

I was just reading your article and someone wrote in and said they were on warfarin and told not to take vitamin C. I also am on warfarin and I've been taking vitamin C because after my surgery a few months ago they gave it to me in the hospital. I asked about taking it at home and was told I could. I was not told for how long. But, since it is cold season I have continued to take it daily along with echinacea and zinc to help ward off any colds. What effect does vitamin C have with warfarin if any? And does taking these other vitamins really help in warding off colds?

Dr. Gourmet Says...

Orange JuiceThere have been isolated reports of interaction between Vitamin C and Coumadin (warfarin). These have not been well supported and it appears that up to 1,000 mg of Vitamin C is safe. Check with your physician about whether he or she feels this would be OK for you.

That said, I don't recommend Vitamin C to patient for any reason. There is no good evidence that taking Vitamin C in supplement form is beneficial. It has not been shown to help in warding off colds. Likewise, the recent research on echinacea and zinc shows no help with prevention or treatment of colds.

Thanks for writing,

Timothy S. Harlan, MD, FACP, CCMS
Dr. Gourmet