Does Levothyroxine Interact With Rifampin?

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine.

Severity: Minor

Severity basis: drug interactions section. Combining Levothyroxine (Thyroid hormone) and Rifampin (Rifamycin antibiotic (strong CYP3A4 inducer)) is classified as a minor interaction.

What to Do

This is generally a minor interaction, but review it with your pharmacist to be sure it is safe for you.

From the FDA Label

Drug or Drug Class Effect Phenobarbital Rifampin Phenobarbital has been shown to reduce the response to thyroxine.

Source: FDA structured product labeling (set_id 008de8fd-150f-4022-8ccb-c8bfa94875c7).

Levothyroxine

Thyroid hormone

Brands: Synthroid, Levoxyl, Euthyrox

View Levothyroxine safety profile

Rifampin

Rifamycin antibiotic (strong CYP3A4 inducer)

Brands: Rifadin

View Rifampin safety profile

Check these against your full medication list in our free Interaction Checker

This information is educational — not medical advice.

This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.

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