Omeprazole and Apalutamide: 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
Apalutamide
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: Apalutamide (Erleada) is a strong "enzyme booster." It speeds up the liver enzymes that break down many other medicines, including omeprazole (Prilosec). In one study, adding apalutamide dropped omeprazole levels in the blood by about 85 percent.
What that means for you is simple: your omeprazole may work much less well, so your heartburn or acid symptoms could come back. This doesn't make omeprazole dangerous, it just makes it weaker. Please don't change anything on your own. Your care team can manage this, sometimes by picking a different acid medicine that apalutamide doesn't weaken. Let your pharmacist or doctor know if your symptoms return.
Mechanism: Apalutamide is a potent inducer of CYP3A4 and CYP2C19. Omeprazole is a CYP2C19 (and partial CYP3A4) substrate, so induction accelerates its metabolism and lowers exposure.
- Direction: reduced omeprazole exposure and diminished acid suppression.
- Magnitude: single-dose data showed an ~85% decrease in omeprazole AUC.
- Onset: unspecified; induction typically develops over days to weeks.
- Evidence: theoretical/PK-based.
Management: Substituting a PPI or acid-reducing agent not primarily reliant on CYP2C19/CYP3A4 is preferred. If coadministration continues, monitor for loss of therapeutic effect (recurrent reflux/dyspepsia symptoms).
What happens
Reduced CYP2C19/CYP3A4 substrate exposure
Interaction Deep Dive
Taking apalutamide together with substrates of CYP3A4 or CYP2C19 can lower the exposure to those substrates. In clinical studies, giving apalutamide alongside midazolam (a CYP3A4 substrate) lowered apalutamide exposure. Likewise, when a single dose of apalutamide was given with the CYP2C19 substrate omeprazole, the omeprazole AUC fell by 85%. During treatment with apalutamide, it is advisable to switch out any drug that is chiefly metabolized through CYP3A4 or CYP2C19. When such coadministration cannot be avoided, monitor the patient for diminished substrate activity1.
Why it happens (mechanism)
Induction of CYP3A4-substrate metabolism by apalutamide; induction of CYP2C19-substrate metabolism by apalutamide
How to manage this interaction
What your care team may do:
- Consider switching you to a different acid-reducing medicine that apalutamide doesn't weaken as much.
- Watch for signs the omeprazole isn't working (heartburn, reflux, stomach discomfort coming back).
What you can do:
- Keep taking both medicines as prescribed unless your prescriber tells you otherwise.
- Tell your pharmacist or doctor if your acid or reflux symptoms return, since that may signal the omeprazole is working less well.
- Ask before adding any new medicine, since apalutamide affects many drugs the same way.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
Common questions
Can I take Omeprazole and Apalutamide together?
Apalutamide can sharply lower omeprazole levels (about 85 percent in one study), so your omeprazole may stop controlling acid as well. Keep taking both, watch for returning symptoms, and ask your care team about an alternative acid medicine. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Apalutamide 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 Apalutamide interaction managed?
What your care team may do: Consider switching you to a different acid-reducing medicine that apalutamide doesn't weaken as much. Watch for signs the omeprazole isn't working (heartburn, reflux, stomach discomfort coming back). What you can do: Keep taking both medicines as prescribed unless your prescriber tells you otherwise. Tell your pharmacist or doctor if your acid or reflux symptoms return,… 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 Apalutamide 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 (2)
Keep reading about Apalutamide
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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