Drug interactions
Isoniazid + Valproic acid
Severity: Moderate
Isoniazid and Valproic acid: 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 may raise valproate concentrations, and both drugs can injure the liver. Together they may increase the risk of hepatotoxicity and valproate-related adverse effects.
What this interaction means in plain words
Isoniazid and Valproic acid 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; Valproic acid belongs to Central Nervous System.
Why it happens
Isoniazid inhibits CYP enzymes and may reduce valproate metabolism, with additive hepatotoxic potential.
What to do
Monitor liver enzymes and valproate levels, and reduce the valproate dose if toxicity or elevated concentrations occur. Counsel patients to report jaundice, vomiting or confusion.
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 Isoniazid
Other interactions of Valproic acid
- Ertapenem + Valproic acid Contraindicated
- Imipenem / cilastatin / relebactam + Valproic acid Contraindicated
- Imipenem / cilastatin + Valproic acid Contraindicated
- Meropenem / vaborbactam + Valproic acid Contraindicated
- Meropenem + Valproic acid Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Valproic acid Major
Frequently asked questions
Can I take Isoniazid with Valproic acid?
MediHelp rates the interaction as moderate. Isoniazid and Valproic acid 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 may raise valproate concentrations, and both drugs can injure the liver. Together they may increase the risk of hepatotoxicity and valproate-related adverse effects.
How serious is the interaction between Isoniazid and Valproic acid?
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 liver enzymes and valproate levels, and reduce the valproate dose if toxicity or elevated concentrations occur. Counsel patients to report jaundice, vomiting or confusion.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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