Abrocitinib and Mavacamten: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mavacamten
Abrocitinib
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.
These two medicines can affect each other in two ways. Abrocitinib (Cibinqo) slows down an enzyme that clears mavacamten (Camzyos) from your body. That can let mavacamten build up, which may raise the chance of side effects like your heart pumping too weakly. At the same time, mavacamten can speed up the breakdown of abrocitinib, which may make your skin medicine work less well.
The good news: your care team can manage this. Mavacamten is a heart medicine that is dosed carefully, so they may lower your dose and check your heart with an ECG. Keep taking both as prescribed and talk with your doctor or pharmacist before making any changes.
Bidirectional CYP interaction. Abrocitinib is a moderate CYP2C19 inhibitor, reducing mavacamten clearance and increasing mavacamten exposure and adverse-reaction risk (including negative inotropy/heart failure). Conversely, mavacamten induces CYP2C19 and CYP2C9, potentially lowering abrocitinib exposure and efficacy. Neither is a prodrug; direction as stated. Evidence: probable; severity major.
- Mavacamten dosing: if already on a moderate 2C19 inhibitor, start at 2.5 mg once daily; if adding the inhibitor, reduce mavacamten to the next lower level (15to10, 10to5, 5to2.5 mg).
- Monitor: clinical and ECG/LVEF assessment at 4 weeks; no up-titration until 12 weeks post-initiation.
- Avoid adding inhibitor if on 2.5 mg (no lower dose). Consider mavacamten increase if inhibitor discontinued after long-term use.
What happens
Increased mavacamten exposure, an increased risk of mavacamten-related adverse reactions, reduced abrocitinib exposure and reduced efficacy of abrocitinib
Interaction Deep Dive
Taking mavacamten together with abrocitinib (a moderate CYP2C19 inhibitor) can raise mavacamten exposure, potentially heightening the likelihood of mavacamten-related adverse reactions. Because mavacamten (an inducer of CYP2C19 and CYP2C9) may lower abrocitinib exposure and consequently diminish abrocitinib efficacy when combined with abrocitinib (a substrate of CYP2C19 and CYP2C9), close monitoring is warranted. For patients already stabilized on a moderate CYP2C19 inhibitor, begin mavacamten at 2.5 mg orally once daily. When a patient currently taking mavacamten plans to start a moderate CYP2C19 inhibitor, decrease the mavacamten dose to the next lower daily (mg) level (that is, from 15 mg to 10 mg, from 10 mg to 5 mg, or from 5 mg to 2.5 mg). Carry out clinical and ECG evaluation 4 weeks following inhibitor initiation, and refrain from up-titrating mavacamten until 12 weeks after the inhibitor is started. Do not begin a concomitant moderate CYP2C19 inhibitor in patients stable on 2.5 mg of mavacamten, since no lower dose exists. Should the moderate CYP2C19 inhibitor be stopped after prolonged concomitant use, a higher mavacamten dose may become necessary. Watch for symptoms that are new or worsening. Stopping a moderate CYP2C19 inhibitor following long-term concomitant use can lower mavacamten exposure and thereby reduce its efficacy. In cases of short-term use (for example, 1 week), pause mavacamten for the entire period of moderate CYP2C19 inhibitor treatment. Mavacamten can be restarted at the prior dose right after the concomitant therapy is discontinued1.
Why it happens (mechanism)
Inhibition of CYP2C19-mediated metabolism of mavacamten; induction of CYP2C19-mediated metabolism of abrocitinib; induction of CYP2C9-mediated metabolism of abrocitinib
How to manage this interaction
Keep taking both as prescribed unless your prescriber tells you otherwise. Because mavacamten is a heart medicine with a narrow safe range, your team will tailor the dose and watch you closely.
- Your mavacamten dose may be lowered (or started lower) when abrocitinib is on board.
- Expect a heart check and ECG around 4 weeks, with no dose increases until about 12 weeks.
- If your abrocitinib seems less effective for your skin, mention it.
- Report new or worsening symptoms like shortness of breath, swelling, dizziness, or fainting.
- Tell your team any time either medicine is started or stopped, since your mavacamten dose may need adjusting.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
3 reports — tap to read
a) A drug interaction study found that taking mavacamten 15 mg together with omeprazole (a CYP2C19 inhibitor) 20 mg once daily raised mavacamten AUC(inf) by 48%, while producing no change in Cmax, in healthy individuals who were CYP2C19 normal and rapid metabolizers 1.
b) A drug interaction study predicts that giving mavacamten once daily to patients with hypertrophic cardiomyopathy (HCM) will lower the AUC and Cmax of TOLBUTamide, a CYP2C9 substrate, by as much as 54% and 23%, respectively, with the extent depending on the mavacamten dose and the CYP2C19 phenotype 1.
c) A drug interaction study predicts that administering mavacamten once daily to HCM patients will lower the AUC and Cmax of omeprazole, a CYP2C19 substrate, by as much as 48% and 17%, respectively, with the extent depending on the mavacamten dose and the CYP2C19 phenotype 1.
Common questions
Can I take Abrocitinib and Mavacamten together?
Combining these can raise mavacamten levels (more side-effect risk) and lower abrocitinib effectiveness, so your team will likely reduce your mavacamten dose and monitor your heart with an ECG. Keep taking both and do not change anything without your prescriber. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abrocitinib 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 Abrocitinib and Mavacamten interaction managed?
Keep taking both as prescribed unless your prescriber tells you otherwise. Because mavacamten is a heart medicine with a narrow safe range, your team will tailor the dose and watch you closely. Your mavacamten dose may be lowered (or started lower) when abrocitinib is on board. Expect a heart check and ECG around 4 weeks, with no dose increases until about 12 weeks. If your abrocitinib seems less… 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.
Questions for your pharmacist
- Does my dose of Abrocitinib 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 Abrocitinib
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist