Drug interactions
Phenobarbital + Topiramate
Severity: Moderate
Phenobarbital and Topiramate: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Phenobarbital adds to topiramate's sedation and cognitive effects, and the combination may cause marked drowsiness. Phenobarbital may also induce metabolism and lower topiramate concentrations, which can affect seizure control.
What this interaction means in plain words
Phenobarbital and Topiramate can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Additive CNS depression, with modest enzyme induction by phenobarbital lowering topiramate exposure.
What to do
Monitor for sedation and cognitive effects, and assess seizure control when either drug is started or stopped. Adjust topiramate dose to clinical response.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Phenobarbital and Topiramate, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Topiramate
Frequently asked questions
Can I take Phenobarbital with Topiramate?
MediHelp rates the interaction as moderate. Phenobarbital and Topiramate can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Phenobarbital adds to topiramate's sedation and cognitive effects, and the combination may cause marked drowsiness. Phenobarbital may also induce metabolism and lower topiramate concentrations, which can affect seizure control.
How serious is the interaction between Phenobarbital and Topiramate?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for sedation and cognitive effects, and assess seizure control when either drug is started or stopped. Adjust topiramate dose to clinical response.
What other medicines interact with Topiramate?
MediHelp also lists interactions of Topiramate with, for example, Benzhydrocodone / acetaminophen, Buprenorphine long-acting, Buprenorphine subdermal implant. The full list is on the Topiramate page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
