Omeprazole and Mavacamten: 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
Mavacamten
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. Omeprazole (a common heartburn medicine) partly blocks the liver enzyme that clears mavacamten (Camzyos) from your body. That means more mavacamten can build up, which can raise the chance of side effects like too much drop in your heart's pumping strength, dizziness, or shortness of breath. At the same time, mavacamten can make omeprazole work a bit less well for your stomach.
The good news is that your care team knows about this and can plan for it. They may start mavacamten at a lower dose, or lower your current dose, and check you with an ECG and symptom review. Please don't change either medicine on your own, just talk with your pharmacist or doctor.
Mechanism: Omeprazole is a moderate CYP2C19 inhibitor, reducing CYP2C19-mediated metabolism of mavacamten and increasing its exposure. A study showed mavacamten AUC(inf) rose ~48% (no Cmax change) in CYP2C19 normal/rapid metabolizers. Reciprocally, mavacamten may induce CYP2C19/CYP3A4, lowering omeprazole exposure and efficacy. Evidence: probable; severity major.
- Stable omeprazole, starting mavacamten: initiate at 2.5 mg once daily.
- Stable mavacamten, adding omeprazole: reduce to next lower dose level; avoid adding omeprazole if already on 2.5 mg.
- Clinical + ECG (LVEF) assessment 4 weeks after inhibitor start; no up-titration until 12 weeks.
- Short-term (~1 week) omeprazole: interrupt mavacamten, resume at prior dose afterward.
- If omeprazole stopped after chronic use, mavacamten dose may need increasing.
What happens
Increased mavacamten exposure, an increased risk of mavacamten-related adverse reactions, reduced omeprazole exposure and reduced efficacy of omeprazole
Interaction Deep Dive
Taking mavacamten together with omeprazole (a moderate CYP2C19 inhibitor that also serves as a substrate of CYP2C19 and CYP3A4) can raise mavacamten exposure, potentially heightening adverse reactions linked to mavacamten, and can lower omeprazole exposure, potentially diminishing omeprazole's effectiveness. For patients already stabilized on omeprazole, begin mavacamten at 2.5 mg by mouth once daily. When patients already receiving mavacamten plan to add omeprazole, drop the mavacamten dose to the next lower daily (mg) level (that is, 15 mg to 10 mg, 10 mg to 5 mg, or 5 mg to 2.5 mg). Carry out clinical and ECG evaluation 4 weeks following inhibitor initiation, and refrain from up-titrating mavacamten to the next higher (mg) dose level until 12 weeks after the inhibitor. Because no lower dose exists, do not start concomitant omeprazole in patients who are stable on 2.5 mg of mavacamten. If omeprazole is stopped after prolonged concomitant use, a higher mavacamten dose may be required. Watch for symptoms that are new or worsening. Stopping a moderate CYP2C19 inhibitor following long-term concomitant use can decrease mavacamten exposure, which can lessen mavacamten efficacy. When omeprazole is used only briefly (for example, 1 week), pause mavacamten throughout the omeprazole treatment period. Mavacamten can be restarted at the prior dose right after the concomitant therapy ends. In a drug interaction study, giving mavacamten 15 mg alongside omeprazole 20 mg once daily raised mavacamten AUC(inf) by 48% while leaving Cmax unchanged in healthy CYP2C19 normal and rapid metabolizers1.
Why it happens (mechanism)
Inhibition of CYP2C19-mediated metabolism of mavacamten; induction of CYP2C19-mediated metabolism of omeprazole; induction of CYP3A4-mediated metabolism of omeprazole
How to manage this interaction
Keep taking both exactly as prescribed and let your care team coordinate the timing and dosing. This is a manageable combination.
- Your team may start mavacamten at a low dose, or lower your current dose, when omeprazole is on board.
- Expect a clinical check and an ECG (heart tracing) around 4 weeks after adding omeprazole, with any dose increases held for about 12 weeks.
- For short omeprazole courses (about a week), your team may pause mavacamten and restart it afterward.
- Report new or worsening symptoms like shortness of breath, dizziness, or fatigue.
Always check with your pharmacist or doctor before starting, stopping, or switching either medicine.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
3 reports — tap to read
a) During a drug interaction study, giving mavacamten 15 mg together with omeprazole 20 mg once daily raised mavacamten AUC(inf) by 48% while producing no change in Cmax in healthy individuals classified as CYP2C19 normal and rapid metabolizers 1.
b) In a drug interaction study, taking mavacamten once daily in patients with hypertrophic cardiomyopathy is projected to lower the AUC and Cmax of omeprazole, a CYP2C19 substrate, by 48% and by 17%, respectively, varying with the mavacamten dose and the CYP2C19 phenotype 1.
c) Administering a 16-day regimen of mavacamten (25 mg on days 1 and 2, then 15 mg for 14 days) together with midazolam (a CYP3A4 substrate) led to a 13% and 7% reduction in midazolam AUC(inf) and Cmax, respectively, in healthy subjects. When mavacamten once daily is coadministered in patients with hypertrophic cardiomyopathy, midazolam AUC(inf) and Cmax are predicted to fall by 45% and 24%, respectively 1.
Common questions
Can I take Omeprazole and Mavacamten together?
Omeprazole raises mavacamten levels (about 48% higher exposure) and can weaken omeprazole's own effect, so your care team will lower or delay mavacamten dosing and check your heart with an ECG. Do not change either drug on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Mavacamten 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 Mavacamten interaction managed?
Keep taking both exactly as prescribed and let your care team coordinate the timing and dosing. This is a manageable combination. Your team may start mavacamten at a low dose, or lower your current dose, when omeprazole is on board. Expect a clinical check and an ECG (heart tracing) around 4 weeks after adding omeprazole, with any dose increases held for about 12 weeks. For short omeprazole course… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
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 Mavacamten 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: CAMZYOS(R) oral capsules, mavacamten oral capsules. Bristol-Myers Squibb Company (per Manufacturer), Princeton, NJ, 2025. DailyMed
Keep reading about Mavacamten
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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