Drug interactions
Isoniazid + Nefazodone
Severity: Major
Isoniazid and Nefazodone: major 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 has weak MAO-inhibiting activity, and nefazodone has serotonergic effects, so the combination could theoretically produce serotonin toxicity. Both drugs are also associated with liver injury, and nefazodone carries a boxed warning for hepatotoxicity, which makes combined use more concerning.
What this interaction means in plain words
Isoniazid and Nefazodone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive serotonergic activity through weak MAO inhibition and serotonin reuptake inhibition, plus additive hepatotoxic potential.
What to do
Avoid the combination where an alternative antidepressant is possible. If used, monitor liver function and watch for serotonin syndrome features.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Isoniazid and Nefazodone, 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 Isoniazid
Frequently asked questions
Can I take Isoniazid with Nefazodone?
MediHelp rates the interaction as major. Isoniazid and Nefazodone can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Isoniazid has weak MAO-inhibiting activity, and nefazodone has serotonergic effects, so the combination could theoretically produce serotonin toxicity. Both drugs are also associated with liver injury, and nefazodone carries a boxed warning for hepatotoxicity, which makes combined use more concerning.
How serious is the interaction between Isoniazid and Nefazodone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where an alternative antidepressant is possible. If used, monitor liver function and watch for serotonin syndrome features.
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.
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.
