Drug interactions
Phenobarbital + Vitamin B6
Severity: Moderate
Phenobarbital and Vitamin B6: 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
High-dose pyridoxine has been reported to reduce serum phenobarbital concentrations in some patients. This could weaken seizure control, though the effect is inconsistent.
What this interaction means in plain words
Phenobarbital and Vitamin B6 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
Pyridoxine may enhance phenobarbital metabolism, but the mechanism is not well established.
What to do
Avoid high-dose pyridoxine in patients on phenobarbital unless needed. If it is used, monitor phenobarbital levels and seizure frequency.
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 Vitamin B6
- Ethotoin + Vitamin B6 Moderate
- Fosphenytoin + Vitamin B6 Moderate
- Isoniazid + Vitamin B6 Moderate
- Levodopa + Vitamin B6 Moderate
- Penicillamine + Vitamin B6 Moderate
- Phenytoin + Vitamin B6 Moderate
Frequently asked questions
Can I take Phenobarbital with Vitamin B6?
MediHelp rates the interaction as moderate. Phenobarbital and Vitamin B6 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. High-dose pyridoxine has been reported to reduce serum phenobarbital concentrations in some patients. This could weaken seizure control, though the effect is inconsistent.
How serious is the interaction between Phenobarbital and Vitamin B6?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid high-dose pyridoxine in patients on phenobarbital unless needed. If it is used, monitor phenobarbital levels and seizure frequency.
What other medicines interact with Vitamin B6?
MediHelp also lists interactions of Vitamin B6 with, for example, Ethotoin, Fosphenytoin, Isoniazid. The full list is on the Vitamin B6 page.
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