Drug interactions
Fentanyl + Isoniazid
Severity: Moderate
Fentanyl 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 can inhibit CYP3A4 to a modest degree and may raise fentanyl exposure. Clinically significant effects are uncommon but possible.
What this interaction means in plain words
Fentanyl 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.
Fentanyl belongs to Musculoskeletal; Isoniazid belongs to Anti Bacterial.
Why it happens
Isoniazid inhibits CYP3A4, reducing fentanyl clearance.
What to do
Monitor for increased sedation and respiratory depression, particularly at the start of isoniazid therapy. Reduce the fentanyl dose if needed.
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 Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
Other interactions of Isoniazid
Frequently asked questions
Can I take Fentanyl with Isoniazid?
MediHelp rates the interaction as moderate. Fentanyl 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 can inhibit CYP3A4 to a modest degree and may raise fentanyl exposure. Clinically significant effects are uncommon but possible.
How serious is the interaction between Fentanyl 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 increased sedation and respiratory depression, particularly at the start of isoniazid therapy. Reduce the fentanyl dose if needed.
What other medicines interact with Fentanyl?
MediHelp also lists interactions of Fentanyl with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Fentanyl page.
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