Does Metronidazole Interact With Phenytoin?

Drugs that Induce CYP450 Enzymes The simultaneous administration of drugs that induce microsomal liver enzymes, such as phenytoin or phenobarbital, may accelerate the elimination of metronidazole, resulting in reduced plasma levels; impaired clearance of phenytoin has also been reported.

Severity: Minor

Severity basis: drug interactions section. Combining Metronidazole (Nitroimidazole antibiotic) and Phenytoin (Anticonvulsant) 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

Drugs that Induce CYP450 Enzymes The simultaneous administration of drugs that induce microsomal liver enzymes, such as phenytoin or phenobarbital, may accelerate the elimination of metronidazole, resulting in reduced plasma levels; impaired clearance of phenytoin has also been reported.

Source: FDA structured product labeling (set_id 02046a22-a5eb-4bb7-bec7-e5a2aa55e142).

Metronidazole

Nitroimidazole antibiotic

Brands: Flagyl

View Metronidazole safety profile

Phenytoin

Anticonvulsant

Brands: Dilantin

View Phenytoin 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 It may be incomplete or out of date, and individual circumstances vary.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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