See the DrugPatentWatch profile for camzyos
Common Side Effects of Camzyos
Camzyos (mavacamten), used to treat symptomatic obstructive hypertrophic cardiomyopathy (HCM), commonly causes dizziness (up to 29% of patients), headache (14%), and syncope or fainting (9%). Other frequent issues include fatigue, palpitations, viral infections, sinus tachycardia, and orthostatic hypotension.1
Serious Side Effects and Risks
The drug carries a boxed warning for embryo-fetal toxicity—it's pregnancy category D and can harm unborn babies, requiring contraception during treatment and for 4 months after. Heart failure risk is elevated; monitor ejection fraction before and during use, as it can drop below 50%, worsening symptoms. Serious adverse reactions include atrial fibrillation (6%), ventricular arrhythmias (3%), and infections like pneumonia.1
How Side Effects Are Monitored
Patients start at 5 mg daily with echocardiograms every 4-12 weeks to check left ventricular ejection fraction (LVEF). Dose adjustments or discontinuation occur if LVEF falls below 50% or symptoms worsen. CYP2C19 genotype testing guides dosing in poor or intermediate metabolizers.[1]
Side Effects by Frequency
| Frequency | Examples |
|-----------|----------|
| ≥10% | Dizziness |
| 5-10% | Syncope, atrial fibrillation |
| 1-5% | Ventricular tachyarrhythmias, heart failure, pneumonia |
| <1% | Noncardiac edema, hypersensitivity |
Data from clinical trials (PIONEER-HCM, VALOR-HCM).1
What Happens If You Experience Side Effects
Report dizziness, fainting, or shortness of breath immediately—may signal reduced heart function needing dose pause or stop. Avoid pregnancy; use effective birth control. No specific antidotes exist; treatment is supportive.[1]
Differences from Other HCM Treatments
Unlike beta-blockers or calcium channel blockers (e.g., verapamil), Camzyos targets myosin ATPase, reducing hypercontractility but adding LVEF monitoring burden. It shows fewer traditional HCM symptoms like chest pain but higher arrhythmia risk vs. mavacamten-naive therapies.2
Patient Concerns and Long-Term Use
Real-world reports highlight persistent dizziness affecting driving/work, plus fatigue impacting daily life. Long-term data (up to 3 years) confirm ongoing risks, with 7% discontinuing due to adverse events. No overdose-specific data, but enhanced monitoring advised.1
[1]: https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/214748s000lbl.pdf (Camzyos Prescribing Information, FDA)