Drug interactions
Isoniazid + Paracetamol
Severity: Moderate
Isoniazid and Paracetamol: 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
Both drugs can injure the liver, and isoniazid alters paracetamol metabolism so that more toxic metabolite may be formed. Patients on isoniazid, especially with alcohol use, malnutrition or liver disease, may be at higher risk of hepatotoxicity from paracetamol.
What this interaction means in plain words
Isoniazid and Paracetamol 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; Paracetamol belongs to Musculoskeletal.
Why it happens
Isoniazid modulates CYP2E1 (inhibits then induces), which can increase formation of the toxic metabolite NAPQI, adding to its own hepatotoxicity.
What to do
Keep paracetamol at the lowest effective dose, avoid chronic high doses and alcohol, and monitor liver enzymes in patients on isoniazid.
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 Isoniazid and Paracetamol, 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 7 days on the web. No card needed.
Other interactions of Paracetamol
- Ethanol + Paracetamol Major
- Busulfan + Paracetamol Moderate
- Carbamazepine + Paracetamol Moderate
- Cholestyramine + Paracetamol Moderate
- Felbamate + Paracetamol Moderate
- Fosphenytoin + Paracetamol Moderate
Other interactions of Isoniazid
Frequently asked questions
Can I take Isoniazid with Paracetamol?
MediHelp rates the interaction as moderate. Isoniazid and Paracetamol 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. Both drugs can injure the liver, and isoniazid alters paracetamol metabolism so that more toxic metabolite may be formed. Patients on isoniazid, especially with alcohol use, malnutrition or liver disease, may be at higher risk of hepatotoxicity from paracetamol.
How serious is the interaction between Isoniazid and Paracetamol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Keep paracetamol at the lowest effective dose, avoid chronic high doses and alcohol, and monitor liver enzymes in patients on isoniazid.
What other medicines interact with Paracetamol?
MediHelp also lists interactions of Paracetamol with, for example, Ethanol, Busulfan, Carbamazepine. The full list is on the Paracetamol 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.
