Does Liothyronine Sodium Interact with Furosemide?
Liothyronine Sodium and Furosemide have a moderate drug interaction according to U.S. FDA drug labeling data. At doses >80 mg IV, furosemide may cause protein binding site displacement. High doses can acutely lower total T4 levels and increase free-T4 fraction by competing for T4-binding sites on TBG, prealbumin, and albumin. The mechanism involves protein binding site displacement and competition for t4-binding sites. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.
- Severity
- Moderate
- Furosemide Class
- Loop Diuretic
- Management
- Monitor for effects
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Liothyronine Sodium and Furosemide occurs because protein binding site displacement and competition for t4-binding sites. Clinically, this means at doses >80 mg iv, furosemide may cause protein binding site displacement. high doses can acutely lower total t4 levels and increase free-t4 fraction by competing for t4-binding sites on tbg, prealbumin, and albumin. This is classified as a moderate interaction. While it may not require stopping either medication, your healthcare provider should be aware you are taking both so they can monitor for potential effects and adjust treatment if necessary.
What To Tell Your Doctor or Pharmacist
If you are taking Liothyronine Sodium and your doctor is considering prescribing Furosemide (or vice versa), make sure to:
- Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
- Ask whether the benefits of combining these medications outweigh the risks for your specific situation
- Ask what symptoms to watch for that would indicate the interaction is causing problems
- Ask whether any dosage adjustments are needed
- Never stop or change either medication without first consulting your healthcare provider