Drug interactions
Diazepam + Isoniazid
Severity: Moderate
Diazepam and Isoniazid: 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 inhibits enzymes involved in diazepam metabolism and can prolong its half-life and increase its effects. This may cause excess sedation and cognitive impairment.
What this interaction means in plain words
Diazepam and Isoniazid 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.
Diazepam belongs to Musculoskeletal; Isoniazid belongs to Anti Bacterial.
Why it happens
Isoniazid inhibits CYP2C19 and CYP3A4, reducing diazepam clearance.
What to do
Monitor for oversedation and reduce the diazepam dose if needed; consider lorazepam or oxazepam.
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 Diazepam and Isoniazid, 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 Diazepam
Other interactions of Isoniazid
Frequently asked questions
Can I take Diazepam with Isoniazid?
MediHelp rates the interaction as moderate. Diazepam and Isoniazid 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 inhibits enzymes involved in diazepam metabolism and can prolong its half-life and increase its effects. This may cause excess sedation and cognitive impairment.
How serious is the interaction between Diazepam and Isoniazid?
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 for oversedation and reduce the diazepam dose if needed; consider lorazepam or oxazepam.
What other medicines interact with Diazepam?
MediHelp also lists interactions of Diazepam with, for example, Calcium / magnesium / potassium / sodium oxybates, Alfentanil, Alprazolam. The full list is on the Diazepam 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.
