Ferrous Fumarate and Levothyroxine: Drug Interaction Guide

Quick answer: This combination requires caution. Ferrous Fumarate and Levothyroxine can be used together with adjustments and monitoring.

Interaction severity: Moderate — caution required

How Ferrous Fumarate interacts with Levothyroxine

Iron forms poorly absorbed complexes with levothyroxine in the gastrointestinal tract, reducing thyroid hormone absorption and potentially increasing TSH.

What you should do

Separate administration by at least four hours. Recheck TSH after starting, stopping, or substantially changing iron therapy and adjust levothyroxine if necessary.

Key facts

Severity

Moderate — caution required

Mechanism

Iron forms poorly absorbed complexes with levothyroxine in the gastrointestinal tract, reducing thyroid hormone absorpti...

Action

Separate administration by at least four hours. Recheck TSH after starting, stopping, or substantially changing iron the...

Important medical disclaimer: This page provides educational information about drug interactions for general reference. It is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss your specific medications with a qualified healthcare provider before starting, stopping, or changing any treatment. About our editorial team.

Frequently asked questions

Can I take Ferrous Fumarate and Levothyroxine together?

With caution. Separate administration by at least four hours. Recheck TSH after starting, stopping, or substantially changing iron therapy and adjust levothyroxine if necessary.

What is the severity of this interaction?

The interaction between Ferrous Fumarate and Levothyroxine is classified as Moderate — caution required. Iron forms poorly absorbed complexes with levothyroxine in the gastrointestinal tract, reducing thyroid hormone absorption and potentially increasing TSH.

What should I do if I'm prescribed both?

Separate administration by at least four hours. Recheck TSH after starting, stopping, or substantially changing iron therapy and adjust levothyroxine if necessary. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

Last reviewed: by iMedic Medical Editorial Team. Our editorial process.