Soy may interfere with thyroid medication
Soy isoflavones may interfere with levothyroxine absorption and possibly thyroid function itself. Effect varies between individuals.
Maintain consistent soy intake. Don't take soy supplements same time as thyroid med.
Separate soy supplements from thyroid medication by 4+ hours
Soy may interfere with thyroid medication. Maintain consistent soy intake. Don't take soy supplements same time as thyroid med.
Separate soy supplements from thyroid medication by 4+ hours
This interaction is rated “Caution” by Formulate. Soy isoflavones may interfere with levothyroxine absorption and possibly thyroid function itself. Effect varies between individuals.
Studies from our registry that mention soy or thyroid medication. Each links to the primary source and the other Formulate pages citing it.
Other interactions to know
Ashwagandha can raise thyroid hormone levels and stack additively with levothyroxine, risking thyrotoxicosis.
Calcium blocks thyroid medication absorption
Iron reduces levothyroxine absorption
Iodine supplementation can destabilize thyroid
Magnesium may reduce thyroid med absorption
Selenium supports thyroid hormone conversion
Check your full stack in the free interaction checker.
The free checker lets you add any combination of supplements and medications at once. The free web app goes further — every stack change surfaces interaction alerts automatically.
Medical disclaimer. This page is for educational purposes only and does not replace advice from a qualified healthcare provider.
Last medically reviewed: