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Moderate· limited-evidence
May be possible under supervision — talk to your prescriber or pharmacist before combining.
Kelp may contain significant vitamin K, which antagonizes warfarin, and its iodine content can affect thyroid-driven clotting factor turnover. Keep kelp intake consistent and monitor INR.
Vitamin K in kelp supports clotting factor synthesis opposing warfarin; variable iodine intake adds instability via thyroid effects on coagulation.
Source: Natural Medicines Database · Reviewed September 2026
Kelp + Warfarin (Coumadin): use caution. May be possible under supervision — talk to your prescriber or pharmacist before combining. Kelp may contain significant vitamin K, which antagonizes warfarin, and its iodine content can affect thyroid-driven clotting factor turnover. Keep kelp intake consistent and monitor INR.
Vitamin K in kelp supports clotting factor synthesis opposing warfarin; variable iodine intake adds instability via thyroid effects on coagulation.
Do not stop either abruptly on your own. Talk to your prescriber or pharmacist promptly — bring this page to your appointment.
Educational information only — not medical advice. Always verify with a healthcare professional.