Drug interactions
Diclofenac + Phenobarbital
Severity: Minor
Diclofenac and Phenobarbital: minor 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
Phenobarbital is an enzyme inducer, including of CYP2C9, and may lower diclofenac plasma concentrations. This may reduce analgesic or anti-inflammatory efficacy during long-term co-use.
What this interaction means in plain words
Diclofenac and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Phenobarbital induces CYP2C9, accelerating diclofenac metabolism.
What to do
Monitor for loss of diclofenac effect and adjust the dose within labeled limits or choose another analgesic if response is inadequate.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Diclofenac and Phenobarbital, 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 Diclofenac
- Diclofenac + Ketorolac Contraindicated
- Diclofenac + Ketorolac intranasal Contraindicated
- Aceclofenac + Diclofenac Major
- Acemetacin + Diclofenac Major
- Alteplase + Diclofenac Major
- Amiloride + Diclofenac Major
Frequently asked questions
Can I take Diclofenac with Phenobarbital?
MediHelp rates the interaction as minor. Diclofenac and Phenobarbital have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenobarbital is an enzyme inducer, including of CYP2C9, and may lower diclofenac plasma concentrations. This may reduce analgesic or anti-inflammatory efficacy during long-term co-use.
How serious is the interaction between Diclofenac and Phenobarbital?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for loss of diclofenac effect and adjust the dose within labeled limits or choose another analgesic if response is inadequate.
What other medicines interact with Diclofenac?
MediHelp also lists interactions of Diclofenac with, for example, Ketorolac, Ketorolac intranasal, Aceclofenac. The full list is on the Diclofenac 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.
