Omeprazole and Vismodegib: 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
Vismodegib
Omeprazole
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 what's going on. Vismodegib (Erivedge) is a cancer medicine that needs an acidic stomach to dissolve well and be absorbed into your body. Omeprazole (Prilosec) lowers stomach acid. When you take them together, your body may absorb less of the vismodegib, which could make the cancer medicine work less well.
One important point: taking a higher dose of vismodegib will not make up for this. The good news is your care team can plan around it, whether that means watching how well your treatment is working or looking at other options for heartburn. Please don't stop either medicine on your own. Just bring it up with your pharmacist or doctor so they can guide you.
Mechanism: Omeprazole raises gastric pH, reducing the pH-dependent solubility and oral bioavailability of vismodegib, lowering its systemic exposure (AUC).
Direction: Reduced vismodegib effect (potential loss of efficacy). Neither agent is affected in the reverse direction here.
- Severity: Major
- Evidence: Theoretical
- Onset: Unspecified
- Note: Increasing the vismodegib dose does not compensate for lost exposure.
Management: If co-administration is necessary, monitor for reduced vismodegib efficacy (oncologic response). Consider whether continued acid suppression is required, and involve the prescribing oncologist in that decision.
What happens
Reduced vismodegib systemic exposure
Interaction Deep Dive
When vismodegib is taken together with agents that raise gastric pH, including omeprazole, the solubility and bioavailability of vismodegib can be reduced, which in turn lowers its systemic exposure. Raising the vismodegib dose does not offset this reduction in exposure1. Should concurrent administration of omeprazole and vismodegib be required, watch for reduced vismodegib efficacy.
Why it happens (mechanism)
Altered gastric pH
How to manage this interaction
What the care team may do:
- Monitor how well your vismodegib is working, since acid-lowering drugs can reduce how much is absorbed.
- Review whether you still need omeprazole, or whether another approach to your stomach symptoms fits better. This should be individualized by your team.
- Remember that a bigger vismodegib dose will not fix the reduced absorption, so that is not the solution.
What you should do:
- Keep taking both exactly as prescribed unless your doctor tells you otherwise.
- Tell your pharmacist and oncologist about every acid-reducing product you use, including over-the-counter ones.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Omeprazole and Vismodegib together?
Omeprazole can lower how much vismodegib your body absorbs, which may weaken the cancer medicine, and raising the vismodegib dose won't fix it. Keep taking both as prescribed and ask your oncologist or pharmacist whether the acid reducer is still needed. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Vismodegib 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 Vismodegib interaction managed?
What the care team may do: Monitor how well your vismodegib is working, since acid-lowering drugs can reduce how much is absorbed. Review whether you still need omeprazole, or whether another approach to your stomach symptoms fits better. This should be individualized by your team. Remember that a bigger vismodegib dose will not fix the reduced absorption, so that is not the solution. What you sho… 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 Vismodegib 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: ERIVEDGE(TM) oral capsules, vismodegib oral capsules. Genentech USA, Inc. (per FDA), South San Francisco, CA, 2012. DailyMed
Keep reading about Vismodegib
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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