Mavacamten side effects: what 5,020 FDA adverse event reports show
Drug class
Cardiac Myosin Inhibitor
Brand names
Camzyos
Who reports
5,020 reports · 43% serious · 127 with death outcome · 69% female
Used for
CAMZYOS ® is indicated for the treatment of adults with symptomatic New York Heart Association (NYHA) class II-III obstructive hypertrophic cardiomyopathy (HCM) to improve functional capacity and symptoms. CAMZYOS is a cardiac myosin inhibitor indicate.
What it is
CAMZYOS capsules for oral use contain mavacamten, a cardiac myosin inhibitor.
Boxed warning
RISK OF HEART FAILURE CAMZYOS reduces left ventricular ejection fraction (LVEF) and can cause heart failure due to systolic dysfunction [see Warnings and Precautions (5.1) ] . Echocardiogram assessments of LVEF are required prior to and during treatment with CAMZYOS. Initiation of CAMZYOS in patients with LVEF <55% is not recommended.
Causality screen of the 40 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 54 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Ejection fraction decreased | 181 | 48.5 42.0–56.0ROR 50.3 · χ² 8,286 / p <1e-300 | 47.7 EB05 42.2 · IC025 +5.2 3/3 methods agree | Lab value / disease marker | serious PRR 39.8 | no trial data cached |
| Mitral valve incompetence | 66 | 24.2 19.0–30.8ROR 24.5 · χ² 1,437 / p <1e-300 | 23.9 EB05 19.5 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious PRR 33.0 | no trial data cached |
| Atrial fibrillation | 325 | 13.8 12.4–15.3ROR 14.7 · χ² 3,849 / p <1e-300 | 13.7 EB05 12.5 · IC025 +3.6 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 19.0 | no trial data cached |
| Cardiogenic shock | 36 | 10.4 7.5–14.5ROR 10.5 · χ² 297 / p 7e-67 | 9.9 EB05 7.3 · IC025 +2.6 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 14.2 · 100% clinician | no trial data cached |
| Therapy interrupted | 142 | 8.5 7.2–10.0ROR 8.7 · χ² 935 / p 1e-205 | 8.3 EB05 7.2 · IC025 +2.8 3/3 methods agree | Reporting / coding artifact | serious PRR 11.7 · 72% consumer | no trial data cached |
| Insurance issue | 30 | 8.3 5.8–11.9ROR 8.4 · χ² 187 / p 9e-43 | 7.6 EB05 5.5 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 7.8 | no trial data cached |
| Tooth disorder | 45 | 8.3 6.2–11.1ROR 8.4 · χ² 282 / p 1e-63 | 7.8 EB05 6.0 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 3.5 · 84% consumer | no trial data cached |
| Dizziness postural | 18 | 7.7 4.9–12.3ROR 7.8 · χ² 99 / p 1e-23 | 6.7 EB05 4.4 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Dyspnoea exertional | 58 | 6.4 4.9–8.2ROR 6.4 · χ² 258 / p 2e-58 | 6.1 EB05 4.9 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.7 | no trial data cached |
| Adverse event | 133 | 6.0 5.0–7.1ROR 6.1 · χ² 546 / p 4e-121 | 5.8 EB05 5.1 · IC025 +2.3 3/3 methods agree | Reporting / coding artifact | serious PRR 6.6 | no trial data cached |
| Ventricular tachycardia | 23 | 5.7 3.8–8.6ROR 5.8 · χ² 85 / p 1e-20 | 5.2 EB05 3.6 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 7.9 | no trial data cached |
| Product dose omission in error | 36 | 5.5 4.0–7.7ROR 5.6 · χ² 129 / p 3e-30 | 5.2 EB05 3.9 · IC025 +1.8 3/3 methods agree | Reporting / coding artifact | serious PRR 8.3 · 78% consumer | no trial data cached |
| Palpitations (pounding heartbeat) | 153 | 5.4 4.6–6.3ROR 5.5 · χ² 547 / p 3e-121 | 5.3 EB05 4.6 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.7 | no trial data cached |
| Cardiac failure (heart failure) | 104 | 5.3 4.4–6.5ROR 5.4 · χ² 364 / p 2e-81 | 5.2 EB05 4.4 · IC025 +2.1 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 7.3 | no trial data cached |
| Product use issue | 240 | 5.3 4.7–6.0ROR 5.5 · χ² 840 / p 5e-185 | 5.2 EB05 4.7 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 1.8 · 82% consumer | no trial data cached |
| Respiratory tract congestion | 19 | 4.9 3.1–7.7ROR 4.9 · χ² 56 / p 4e-14 | 4.4 EB05 3.0 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 | no trial data cached |
| Brain fog | 17 | 4.8 3.0–7.7ROR 4.8 · χ² 48 / p 3e-12 | 4.3 EB05 2.9 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 5.2 | no trial data cached |
| Ventricular extrasystoles | 12 | 4.8 2.7–8.4ROR 4.8 · χ² 32 / p 8e-9 | 4.1 EB05 2.5 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 2.4 | no trial data cached |
| Cardiomyopathy | 17 | 4.7 3.0–7.6ROR 4.8 · χ² 47 / p 4e-12 | 4.2 EB05 2.8 · IC025 +1.3 3/3 methods agree | Likely indication confounding term in indications | serious PRR 6.5 | no trial data cached |
| Product dose omission issue | 323 | 4.7 4.2–5.2ROR 4.9 · χ² 945 / p 1e-207 | 4.7 EB05 4.2 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious PRR 3.4 · 81% consumer | no trial data cached |
| Laryngitis | 12 | 4.6 2.6–8.0ROR 4.6 · χ² 30 / p 2e-8 | 3.9 EB05 2.4 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious n=8 | no trial data cached |
| Adverse drug reaction | 93 | 4.3 3.5–5.3ROR 4.4 · χ² 232 / p 9e-53 | 4.2 EB05 3.5 · IC025 +1.7 3/3 methods agree | Reporting / coding artifact | serious PRR 0.7 · 90% consumer | no trial data cached |
| Tooth infection | 13 | 4.1 2.4–7.0ROR 4.1 · χ² 27 / p 1e-7 | 3.6 EB05 2.3 · IC025 +0.9 3/3 methods agree | Not in label — unassessed | serious PRR 1.4 | no trial data cached |
| Chest pain | 161 | 3.6 3.1–4.2ROR 3.7 · χ² 300 / p 2e-67 | 3.5 EB05 3.1 · IC025 +1.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.1 | no trial data cached |
| Treatment noncompliance | 47 | 3.6 2.7–4.7ROR 3.6 · χ² 85 / p 2e-20 | 3.5 EB05 2.7 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious PRR 1.6 | no trial data cached |
| Seasonal allergy | 12 | 3.5 2.0–6.2ROR 3.5 · χ² 19 / p 6e-6 | 3.2 EB05 2.0 · IC025 +0.7 | Not in label — unassessed | serious n=1 | no trial data cached |
| Gout | 15 | 3.4 2.1–5.7ROR 3.5 · χ² 24 / p 6e-7 | 3.2 EB05 2.1 · IC025 +0.8 3/3 methods agree | Not in label — unassessed | serious PRR 2.4 | no trial data cached |
| Blood pressure abnormal | 16 | 3.3 2.0–5.4ROR 3.3 · χ² 24 / p 5e-7 | 3.1 EB05 2.0 · IC025 +0.8 3/3 methods agree | Lab value / disease marker | serious PRR 1.7 | no trial data cached |
| Peripheral swelling | 123 | 3.3 2.8–3.9ROR 3.4 · χ² 197 / p 4e-45 | 3.3 EB05 2.8 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 2.0 | no trial data cached |
| Circumstance or information capable of leading to medication error | 26 | 3.2 2.2–4.7ROR 3.2 · χ² 37 / p 5e-10 | 3.1 EB05 2.2 · IC025 +1.0 3/3 methods agree | Labeled (related wording) related wording | serious n=1 · 81% consumer | no trial data cached |
| Nasopharyngitis (common cold) | 143 | 3.2 2.7–3.8ROR 3.3 · χ² 215 / p 5e-49 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 1.6 · 83% consumer | no trial data cached |
| Product prescribing issue | 15 | 3.0 1.8–5.0ROR 3.0 · χ² 19 / p 8e-6 | 2.8 EB05 1.8 · IC025 +0.6 | Reporting / coding artifact | serious PRR 1.5 | no trial data cached |
| Angina pectoris | 20 | 2.9 1.8–4.4ROR 2.9 · χ² 22 / p 1e-6 | 2.7 EB05 1.9 · IC025 +0.7 | Not in label — unassessed | serious PRR 4.0 | no trial data cached |
| Chest discomfort | 67 | 2.7 2.1–3.4ROR 2.7 · χ² 71 / p 2e-17 | 2.7 EB05 2.2 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 2.1 | no trial data cached |
| Syncope (fainting) | 63 | 2.6 2.0–3.3ROR 2.6 · χ² 61 / p 4e-15 | 2.6 EB05 2.1 · IC025 +0.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.8 | no trial data cached |
| Heart rate decreased | 22 | 2.6 1.7–3.9ROR 2.6 · χ² 20 / p 5e-6 | 2.5 EB05 1.7 · IC025 +0.6 | Lab value / disease marker | serious PRR 3.6 · ♀ 90% (drug 69%) | no trial data cached |
| Gallbladder disorder | 11 | 2.5 1.4–4.6ROR 2.5 · χ² 9 / p 0.002 | 2.4 EB05 1.4 · IC025 +0.2 | Not in label — unassessed | serious PRR 2.8 | no trial data cached |
| Dyspnoea (shortness of breath) | 344 | 2.5 2.3–2.8ROR 2.6 · χ² 320 / p 8e-72 | 2.5 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.0 | no trial data cached |
| Toothache | 11 | 2.5 1.4–4.5ROR 2.5 · χ² 9 / p 0.002 | 2.4 EB05 1.4 · IC025 +0.2 | Not in label — unassessed | – | no trial data cached |
| Urinary tract infection (bladder infection) | 103 | 2.5 2.1–3.0ROR 2.5 · χ² 92 / p 5e-22 | 2.5 EB05 2.1 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 1.5 · ♀ 95% (drug 69%) | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Dyspnoea (shortness of breath) | 344 | 2.5 2.3–2.8ROR 2.6 · χ² 320 / p 8e-72 | 2.5 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.0 | no trial data cached |
| Atrial fibrillation | 325 | 13.8 12.4–15.3ROR 14.7 · χ² 3,849 / p <1e-300 | 13.7 EB05 12.5 · IC025 +3.6 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 19.0 | no trial data cached |
| Product dose omission issue | 323 | 4.7 4.2–5.2ROR 4.9 · χ² 945 / p 1e-207 | 4.7 EB05 4.2 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious PRR 3.4 · 81% consumer | no trial data cached |
| Dizziness | 300 | 2.5 2.2–2.8ROR 2.6 · χ² 272 / p 2e-61 | 2.5 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.4 | no trial data cached |
| Product use issue | 240 | 5.3 4.7–6.0ROR 5.5 · χ² 840 / p 5e-185 | 5.2 EB05 4.7 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 1.8 · 82% consumer | no trial data cached |
| Ejection fraction decreased | 181 | 48.5 42.0–56.0ROR 50.3 · χ² 8,286 / p <1e-300 | 47.7 EB05 42.2 · IC025 +5.2 3/3 methods agree | Lab value / disease marker | serious PRR 39.8 | no trial data cached |
| Chest pain | 161 | 3.6 3.1–4.2ROR 3.7 · χ² 300 / p 2e-67 | 3.5 EB05 3.1 · IC025 +1.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.1 | no trial data cached |
| Palpitations (pounding heartbeat) | 153 | 5.4 4.6–6.3ROR 5.5 · χ² 547 / p 3e-121 | 5.3 EB05 4.6 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.7 | no trial data cached |
| Nasopharyngitis (common cold) | 143 | 3.2 2.7–3.8ROR 3.3 · χ² 215 / p 5e-49 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 1.6 · 83% consumer | no trial data cached |
| Therapy interrupted | 142 | 8.5 7.2–10.0ROR 8.7 · χ² 935 / p 1e-205 | 8.3 EB05 7.2 · IC025 +2.8 3/3 methods agree | Reporting / coding artifact | serious PRR 11.7 · 72% consumer | no trial data cached |
| Adverse event | 133 | 6.0 5.0–7.1ROR 6.1 · χ² 546 / p 4e-121 | 5.8 EB05 5.1 · IC025 +2.3 3/3 methods agree | Reporting / coding artifact | serious PRR 6.6 | no trial data cached |
| Peripheral swelling | 123 | 3.3 2.8–3.9ROR 3.4 · χ² 197 / p 4e-45 | 3.3 EB05 2.8 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 2.0 | no trial data cached |
| Weight increased (weight gain) | 121 | 2.2 1.9–2.7ROR 2.3 · χ² 83 / p 4e-20 | 2.2 EB05 1.9 · IC025 +0.9 | Not in label — unassessed | serious PRR 1.3 · 70% consumer | no trial data cached |
| Cardiac failure (heart failure) | 104 | 5.3 4.4–6.5ROR 5.4 · χ² 364 / p 2e-81 | 5.2 EB05 4.4 · IC025 +2.1 3/3 methods agree | Labeled — boxed warning synonym match | serious PRR 7.3 | no trial data cached |
| Urinary tract infection (bladder infection) | 103 | 2.5 2.1–3.0ROR 2.5 · χ² 92 / p 5e-22 | 2.5 EB05 2.1 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 1.5 · ♀ 95% (drug 69%) | no trial data cached |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Mitral valve incompetence — n=66, PRR 24.2
- Insurance issue — n=30, PRR 8.3
- Tooth disorder — n=45, PRR 8.3
- Dyspnoea exertional — n=58, PRR 6.4
- Ventricular tachycardia — n=23, PRR 5.7
- Peripheral swelling — n=123, PRR 3.3
- Nasopharyngitis — n=143, PRR 3.2
- Angina pectoris — n=20, PRR 2.9
- Chest discomfort — n=67, PRR 2.7
- Urinary tract infection — n=103, PRR 2.5
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Mavacamten?
In FDA FAERS, the most frequently co-reported reaction terms for Mavacamten are dyspnoea, atrial fibrillation, dizziness, ejection fraction decreased, chest pain, palpitations. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Mavacamten have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: RISK OF HEART FAILURE CAMZYOS reduces left ventricular ejection fraction (LVEF) and can cause heart failure due to systolic dysfunction [see Warnings and Precautions (5.1) ] . Echocardiogram assessments of LVEF are required prior to and during treatment with CAMZYOS. Initiation of CAMZYOS in patients with LVEF <55% is not recommended.
Do FAERS signals prove that Mavacamten causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 669c936b-3ee6-4e36-8a22-79dd11b1255b, effective 20250417; matched on
openfda.generic_name.exact:"MAVACAMTEN") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 94 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.