Calcium blocks thyroid medication absorption
Calcium binds to levothyroxine (Synthroid) in the gut, reducing absorption by up to 60%. This can lead to subtherapeutic thyroid levels and hypothyroid symptoms.
Take thyroid medication at least 4 hours before or after calcium supplements.
Separate by 4+ hours; thyroid med first thing in morning
Calcium blocks thyroid medication absorption. Take thyroid medication at least 4 hours before or after calcium supplements.
Separate by 4+ hours; thyroid med first thing in morning
This interaction is rated “Warning” by Formulate. Calcium binds to levothyroxine (Synthroid) in the gut, reducing absorption by up to 60%. This can lead to subtherapeutic thyroid levels and hypothyroid symptoms.
The free checker lets you add any combination of supplements and medications at once. Formulate's desktop 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.