Omeprazole and Belumosudil: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Belumosudil
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. Belumosudil (Rezurock) is the medicine treating your graft-versus-host disease. Omeprazole (Prilosec) lowers the acid in your stomach. It turns out belumosudil needs a somewhat acidic stomach to dissolve and get absorbed well. When omeprazole makes your stomach less acidic, your body takes in less belumosudil, so it may not work as well as it should.
The good news is that this is very manageable. Your care team knows about this and can adjust your belumosudil dose so you still get the benefit. Please don't change either medicine on your own. Just check in with your pharmacist or doctor so they can make sure your dose is right for you.
Mechanism: Omeprazole raises gastric pH, reducing the pH-dependent dissolution and absorption of belumosudil. Neither agent's activity depends on prodrug conversion here; the effect is a straightforward reduction in belumosudil exposure.
Direction/magnitude: In healthy-subject PK studies, omeprazole decreased belumosudil Cmax by ~68% and AUC by ~47% (rabeprazole reduced Cmax ~87%, AUC ~80%). This may reduce belumosudil efficacy.
- Evidence: theoretical/PK-based; severity rated major.
- Onset: unspecified.
- Management: If coadministered, increase belumosudil to 200 mg twice daily. Monitor clinical response (GVHD control).
What happens
Reduced belumosudil exposure
Interaction Deep Dive
Taking belumosudil together with a proton pump inhibitor can lower belumosudil exposure and thereby potentially diminish its effectiveness. Drug interaction studies conducted in healthy subjects showed that giving belumosudil alongside the proton pump inhibitors rabeprazole and omeprazole reduced belumosudil Cmax by 87% and 68%, and AUC by 80% and 47%, respectively. When belumosudil is given concurrently with a proton pump inhibitor, the belumosudil dose should be raised to 200 mg twice daily1.
Why it happens (mechanism)
Increased gastric pH by proton pump inhibitors
How to manage this interaction
This interaction is expected and manageable. The key point is that omeprazole can lower how much belumosudil your body absorbs, which could weaken its effect.
- Keep taking both medicines as prescribed unless your care team tells you otherwise.
- The documented fix is that your team may increase belumosudil to 200 mg twice daily when it is taken with a proton pump inhibitor like omeprazole. This dose should be individualized by your prescriber.
- Your team may also monitor your response to make sure the belumosudil is still controlling your condition.
Tell your pharmacist or doctor that you take both, so they can confirm the right dose for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) In a drug interaction study conducted in healthy subjects, giving belumosudil together with rabeprazole (a proton pump inhibitor) reduced the Cmax of belumosudil by 87% and its AUC by 80%.1.
b) In a drug interaction study conducted in healthy subjects, giving belumosudil together with omeprazole (a proton pump inhibitor) reduced the Cmax of belumosudil by 68% and its AUC by 47%.1.
Common questions
Can I take Omeprazole and Belumosudil together?
Omeprazole can substantially lower how much belumosudil your body absorbs, possibly weakening it, but your care team can manage this, often by increasing belumosudil to 200 mg twice daily. Don't change either drug yourself; confirm your dose with your prescriber or pharmacist. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Belumosudil 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 Belumosudil interaction managed?
This interaction is expected and manageable. The key point is that omeprazole can lower how much belumosudil your body absorbs, which could weaken its effect. Keep taking both medicines as prescribed unless your care team tells you otherwise. The documented fix is that your team may increase belumosudil to 200 mg twice daily when it is taken with a proton pump inhibitor like omeprazole. This dose… 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 Belumosudil 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: REZUROCK(R) oral tablets, belumosudil oral tablets. Kadmon Pharmaceuticals LLC (per FDA), Bridgewater, NJ, 2024. DailyMed
Keep reading about Belumosudil
Keep reading about Omeprazole
These medications also interact with supplements
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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