Drug interactions
Isoniazid + Vitamin B6
Severity: Moderate
Isoniazid 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
Isoniazid depletes pyridoxine and can cause peripheral neuropathy and, less commonly, CNS effects such as seizures. Patients at higher risk include those with malnutrition, diabetes, alcohol use, HIV, pregnancy, renal disease or slow acetylator status.
What this interaction means in plain words
Isoniazid 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.
Isoniazid belongs to Anti Bacterial; Vitamin B6 belongs to Gastrointestinal Tract.
Why it happens
Isoniazid forms hydrazones with pyridoxal and inhibits pyridoxal phosphokinase, reducing active pyridoxal phosphate and increasing urinary pyridoxine loss.
What to do
Give prophylactic pyridoxine to at-risk patients on isoniazid, commonly 10 to 25 mg daily, and use higher therapeutic doses if neuropathy develops. Monitor for neurologic symptoms.
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
- Levodopa + Vitamin B6 Moderate
- Penicillamine + Vitamin B6 Moderate
- Phenobarbital + Vitamin B6 Moderate
- Phenytoin + Vitamin B6 Moderate
Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Vitamin B6?
MediHelp rates the interaction as moderate. Isoniazid 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. Isoniazid depletes pyridoxine and can cause peripheral neuropathy and, less commonly, CNS effects such as seizures. Patients at higher risk include those with malnutrition, diabetes, alcohol use, HIV, pregnancy, renal disease or slow acetylator status.
How serious is the interaction between Isoniazid 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: Give prophylactic pyridoxine to at-risk patients on isoniazid, commonly 10 to 25 mg daily, and use higher therapeutic doses if neuropathy develops. Monitor for neurologic symptoms.
What other medicines interact with Vitamin B6?
MediHelp also lists interactions of Vitamin B6 with, for example, Ethotoin, Fosphenytoin, Levodopa. The full list is on the Vitamin B6 page.
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