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Camzyos Side Effects

Generic name: mavacamten

Medically reviewed by Last updated on Dec 21, 2022.

Note: This document contains side effect information about mavacamten. Some dosage forms listed on this page may not apply to the brand name Camzyos.

Applies to mavacamten: oral capsule.


Oral route (Capsule)

Risk of Heart FailureMavacamten reduces left ventricular ejection fraction (LVEF) and can cause heart failure due to systolic dysfunction.Echocardiogram assessments of LVEF are required prior to and during treatment with mavacamten. Initiation of mavacamten in patients with LVEF less than 55% is not recommended. Interrupt mavacamten if LVEF is less than 50% at any visit or if the patient experiences heart failure symptoms or worsening clinical status.Concomitant use of mavacamten with certain cytochrome P450 inhibitors or discontinuation of certain P450 inducers may increase the risk of heart failure due to systolic dysfunction; therefore, the use of mavacamten is contraindicated with the following: moderate to strong CYP2C19 inhibitors or strong CYP3A4 inhibitors, and moderate to strong CYP2C19 inducers or moderate to strong CYP3A4 inducers.Because of the risk of heart failure due to systolic dysfunction, mavacamten is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS), called Camzyos REMS Program.

Serious side effects of Camzyos

Along with its needed effects, mavacamten (the active ingredient contained in Camzyos) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking mavacamten:

More common

Incidence not known

  • Chest pain or tightness
  • decreased urine output
  • dilated neck veins
  • irregular breathing
  • irregular heartbeat
  • swelling of the face, fingers, feet, or lower legs
  • trouble breathing
  • unusual tiredness or weakness
  • weight gain

For Healthcare Professionals

Applies to mavacamten: oral capsule.


In a clinical trial, mean resting LVEF was 74% at baseline in patients treated with this drug and those treated with placebo. Mean absolute change from baseline in LVEF was -4% with this drug and 0% with placebo over the 30-week treatment period. At Week 38 (after an 8-week interruption of trial drug), mean LVEF was similar to baseline for both treatment groups. In the clinical trial, 7 patients (6%) taking this drug and 2 patients (2%) taking placebo had reversible reductions in LVEF to less than 50% (median: 48%; range: 35% to 49%) during therapy; in 3 of the 7 patients taking this drug and 1 of the 2 placebo patients taking placebo, these reductions were asymptomatic. LVEF recovered after therapy interruption in all 7 patients treated with this drug.[Ref]

Common (1% to 10%): Reduced left ventricular ejection fraction (LVEF)

Frequency not reported: Reduced systolic contraction[Ref]

Nervous system

Very common (10% or more): Dizziness (up to 27%)

Common (1% to 10%): Syncope[Ref]


1. Product Information. Camzyos (mavacamten). MyoKardia Inc. 2022.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.