This page explains what happens if Levothyroxine and Warfarin are taken together, according to official sources.
INR monitoring advised during thyroid stabilization
Thyroid hormone status influences clotting factor catabolism. While large population studies show levothyroxine initiation is not associated with a significantly elevated risk of major hemorrhage, gradual metabolic changes can alter INR stability.
Monitor INR within 2–4 weeks after starting or titrating levothyroxine and adjust warfarin based on objective INR results rather than empirical proactive dose reductions.
Last updated: Sep 25, 2026
Before changing or stopping any medicine, ask your doctor or pharmacist. Never stop your medicine on your own.