Harvard Heart Letter

Snail's pace for home INR testing

FDA-approved machines allow you to test your blood's clotting potential at home. Why do so few people who take warfarin use them?

Everyone who takes the blood-thinning drug warfarin (Coumadin) — and there are several million of you out there — walks a medication tightrope every day. Take too little warfarin, and you leave yourself open to potentially deadly or disabling blood clots. Take too much, and you're at risk of developing serious bleeding in the stomach or a hemorrhagic stroke (bleeding in the brain). The right amount, though, offers protection against blood clots with a low risk of bleeding problems.

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