Isoniazid and Paracetamol: Drug Interaction Guide

Quick answer: This combination requires caution. Isoniazid and Paracetamol can be used together with adjustments and monitoring.

Interaction severity: Moderate — caution required

How Isoniazid interacts with Paracetamol

Isoniazid induces CYP2E1, increasing formation of the hepatotoxic paracetamol metabolite NAPQI, while also depleting glutathione stores, augmenting risk of hepatotoxicity especially with chronic or high-dose paracetamol.

What you should do

Limit paracetamol to ≤2 g/day in patients on isoniazid, particularly with alcohol use, malnutrition or pre-existing liver disease; monitor LFTs if regular dosing is required.

Key facts

Severity

Moderate — caution required

Mechanism

Isoniazid induces CYP2E1, increasing formation of the hepatotoxic paracetamol metabolite NAPQI, while also depleting glu...

Action

Limit paracetamol to ≤2 g/day in patients on isoniazid, particularly with alcohol use, malnutrition or pre-existing live...

Important medical disclaimer: This page provides educational information about drug interactions for general reference. It is not a substitute for professional medical advice, diagnosis, or treatment. Always discuss your specific medications with a qualified healthcare provider before starting, stopping, or changing any treatment. About our editorial team.

Frequently asked questions

Can I take Isoniazid and Paracetamol together?

With caution. Limit paracetamol to ≤2 g/day in patients on isoniazid, particularly with alcohol use, malnutrition or pre-existing liver disease; monitor LFTs if regular dosing is required.

What is the severity of this interaction?

The interaction between Isoniazid and Paracetamol is classified as Moderate — caution required. Isoniazid induces CYP2E1, increasing formation of the hepatotoxic paracetamol metabolite NAPQI, while also depleting glutathione stores, augmenting risk of hepatotoxicity especially with chronic or high-dose paracetamol.

What should I do if I'm prescribed both?

Limit paracetamol to ≤2 g/day in patients on isoniazid, particularly with alcohol use, malnutrition or pre-existing liver disease; monitor LFTs if regular dosing is required. Always consult your prescribing clinician — do not stop or change medications without medical guidance.

Last reviewed: by iMedic Medical Editorial Team. Our editorial process.