What the label lists and what reports show
Mavacamten side effects
Mavacamten's FDA label lists its adverse reactions in its own words. FAERS holds 5,081 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (352 reports).
- No generic listed
- Boxed warning
Check it at the source: the mavacamten FDA label on DailyMed (effective April 17, 2025, Myokardia, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of CAMZYOS?CAMZYOS may cause serious side effects, including: • Heart failure. See “What is the most important information I should know about CAMZYOS?” The most common side effects of CAMZYOS include: dizziness and fainting (syncope). These are not all of the possible side effects of CAMZYOS. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects to Bristol-Myers Squibb at 1-800-721-5072.
Source: FDA drug label, NDA214998 (Bristol), as published by Myokardia, Inc., effective April 17, 2025 (SPL set 669c936b-3ee6-4e36-8a22-79dd11b1255b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe following adverse reaction is discussed in other sections of the labeling: • Heart failure [see Warnings and Precautions (5.1) ] Adverse reactions occurring in >5% of patients and more commonly on CAMZYOS than on placebo were dizziness (27%) and syncope (6%). ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Bristol-Myers Squibb at 1-800-721-5072 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of CAMZYOS was evaluated in EXPLORER-HCM, a Phase 3, double-blind, randomized, placebo-controlled trial [see Clinical Studies (14) ]. …
Source: FDA drug label, NDA214998 (Bristol), as published by Myokardia, Inc., effective April 17, 2025 (SPL set 669c936b-3ee6-4e36-8a22-79dd11b1255b), via openFDA; the full label on DailyMed
What do FAERS reports show?
5,081 reports list mavacamten among the medicines taken, each a report of something that happened, not proof the medicine caused it; 127 are coded as a death and 891 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Reports rose sharply in 2025 (1,458, against a median of 0 a year): FAERS counts follow reporting, which news, litigation and label changes can drive, not how often a reaction happens. Of the 20 reactions below, 5 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Mavacamten: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions