Does Phenytoin Interact with Acetazolamide?
Phenytoin and Acetazolamide have a moderate drug interaction according to U.S. FDA drug labeling data. Acetazolamide modifies phenytoin metabolism increasing serum levels, which may increase osteomalacia occurrence in patients on chronic therapy. The mechanism involves modifies phenytoin metabolism. 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
- Phenytoin Class
- Anti-epileptic Agent
- Acetazolamide Class
- Carbonic Anhydrase Inhibitor
- Management
- Monitor for effects
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Phenytoin and Acetazolamide occurs because modifies phenytoin metabolism. Clinically, this means acetazolamide modifies phenytoin metabolism increasing serum levels, which may increase osteomalacia occurrence in patients on chronic therapy. 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 Phenytoin and your doctor is considering prescribing Acetazolamide (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