Does Semaglutide (Ozempic) affect the efficacy of Levothyroxine (T4)?

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Last updated: May 17, 2025View editorial policy

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From the Research

Ozempic (semaglutide) may increase the exposure of levothyroxine, and patients taking both medications should monitor their thyroid function tests (TSH, T4) regularly, as their levothyroxine dosage might need adjustment 1. When taking both medications, it's advisable to separate their administration to minimize any potential interference with levothyroxine absorption. Ozempic, as a GLP-1 receptor agonist, can affect the pharmacokinetics of levothyroxine, and a 33% increase in total T4 exposure was observed with levothyroxine/oral semaglutide vs levothyroxine alone 1. Some key points to consider:

  • Patients taking both medications should monitor for signs of hypothyroidism (fatigue, weight gain, cold intolerance) which might indicate reduced levothyroxine effectiveness.
  • Regular thyroid function tests (TSH, T4) are recommended when starting, stopping, or changing the dose of Ozempic while on levothyroxine therapy.
  • If you notice any changes in your thyroid symptoms after starting Ozempic, consult your healthcare provider, as your levothyroxine dosage might need adjustment. It's essential to note that the interaction between Ozempic and levothyroxine is not considered major, but monitoring and potential dosage adjustments are necessary to ensure optimal thyroid hormone levels 1.

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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