Are there any interactions between warfarin and magnesium supplements?

Howard E. Lewine, MD
Probably not, but the conclusion from experiments on a possible interaction are mixed.

There does seem to be some binding of magnesium to warfarin in the intestine. But it remains unclear if this decreases the amount of warfarin that is absorbed, increases it, or has no significant effect at all.

It is best to avoid taking magnesium at the same time you take your warfarin. Take them at least two hours apart. That should eliminate any possible interaction.

Zinc and iron may also bind with warfarin. The same advice applies to them as it does for magnesium.