Omeprazole and Fexinidazole: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fexinidazole
No brand names on recordOmeprazole
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Here's the simple version. Fexinidazole can slow down one of the liver's cleanup enzymes (called CYP3A4). Omeprazole (Prilosec) is partly broken down by that same enzyme. So when you take them together, your body may clear omeprazole a little more slowly, and its level could build up. That could mean more of omeprazole's side effects, like headache, stomach upset, or diarrhea.
I want to be honest with you: this concern is based on how the drugs work rather than on lots of real-world reports, so the actual risk may be modest. Please don't change anything on your own. Your care team can manage this easily by adjusting things or keeping a closer eye on you.
Mechanism: Fexinidazole inhibits CYP3A4. Omeprazole is a CYP3A4 substrate (also CYP2C19), so co-administration may reduce omeprazole clearance and increase its exposure (AUC/Cmax).
Direction: Increased omeprazole concentrations, higher risk of dose-related adverse effects. Neither drug's therapeutic direction is reversed.
- Severity: Major per label.
- Onset: Unspecified.
- Evidence: Theoretical.
- Management: Manufacturer advises avoiding concomitant fexinidazole with CYP3A4 substrates. If used together, individualize dosing and monitor for omeprazole-related adverse effects.
What happens
An increased CYP3A4 substrate exposure
Interaction Deep Dive
Because fexinidazole acts as a CYP3A4 inhibitor, its use together with CYP3A4 substrates should be avoided, since the elevated concentrations of those substrate drugs raise the likelihood of adverse reactions1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by fexinidazole
How to manage this interaction
What your care team may do:
- Consider whether the two drugs should be used together at all, since the fexinidazole labeling advises avoiding CYP3A4 substrates.
- Choose an alternative acid-reducing medication if appropriate.
- Adjust and individualize your dosing and monitor you more closely for side effects if both are needed.
What you should do: Keep taking both exactly as prescribed unless your prescriber tells you otherwise. Let your pharmacist or doctor know you are on both, and mention any new headache, stomach upset, or diarrhea so they can tailor your plan.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Omeprazole and Fexinidazole together?
Fexinidazole may raise omeprazole levels by slowing its breakdown, so the label advises avoiding the combination; talk with your pharmacist or doctor, who can adjust or substitute as needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Fexinidazole interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Omeprazole and Fexinidazole interaction managed?
What your care team may do: Consider whether the two drugs should be used together at all, since the fexinidazole labeling advises avoiding CYP3A4 substrates. Choose an alternative acid-reducing medication if appropriate. Adjust and individualize your dosing and monitor you more closely for side effects if both are needed. What you should do: Keep taking both exactly as prescribed unless your pres… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Omeprazole or Fexinidazole need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: Fexinidazole oral tablets, fexinidazole oral tablets. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2021. DailyMed
Keep reading about Fexinidazole
Keep reading about Omeprazole
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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