Drug interactions
Folic acid + Phenobarbital
Severity: Moderate
Folic acid and Phenobarbital: 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
Folic acid may modestly reduce phenobarbital concentrations, and long-term phenobarbital use is associated with lower folate status. The combination can affect seizure control, so folate supplementation should be monitored in patients with epilepsy.
What this interaction means in plain words
Folic acid and Phenobarbital 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
Phenobarbital induces hepatic enzymes and impairs folate status, while folate may increase anticonvulsant metabolism.
What to do
Monitor seizure frequency and phenobarbital levels when starting or adjusting folic acid. Supplement folate where indicated at the lowest effective dose.
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?
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Other interactions of Folic acid
- Ethotoin + Folic acid Moderate
- Folic acid + Fosphenytoin Moderate
- Folic acid + Glucarpidase Moderate
- Folic acid + Methotrexate Moderate
- Folic acid + Pafolacianine Moderate
- Folic acid + Phenytoin Moderate
Frequently asked questions
Can I take Folic acid with Phenobarbital?
MediHelp rates the interaction as moderate. Folic acid and Phenobarbital 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. Folic acid may modestly reduce phenobarbital concentrations, and long-term phenobarbital use is associated with lower folate status. The combination can affect seizure control, so folate supplementation should be monitored in patients with epilepsy.
How serious is the interaction between Folic acid and Phenobarbital?
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 seizure frequency and phenobarbital levels when starting or adjusting folic acid. Supplement folate where indicated at the lowest effective dose.
What other medicines interact with Folic acid?
MediHelp also lists interactions of Folic acid with, for example, Ethotoin, Fosphenytoin, Glucarpidase. The full list is on the Folic acid page.
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