Drug · FAERS side-effect profile with label screen
Letermovir side effects: what 3,121 FDA adverse event reports show
Drug class
Cytomegalovirus DNA Terminase Complex Inhibitor
FDA label (Established Pharmacologic Class)
Brand names
Prevymis
openFDA label
Who reports
3,121 reports · 82% serious · 580 with death outcome · 43% female
openFDA FAERS counts, all years, deduplication not applied
Used for
PREVYMIS is a CMV DNA terminase complex inhibitor indicated for: Prophylaxis of cytomegalovirus (CMV) infection and disease in adult and pediatric patients 6 months of age and older and weighing at least 6 kg who are CMV-seropositive recipients [R+] of an allogeneic hematopoietic stem cell transplant (HSCT).
FDA label, Indications and Usage
What it is
PREVYMIS contains letermovir, an inhibitor of the CMV DNA terminase complex, and is administered orally or by intravenous infusion. Letermovir has a molecular formula of C 29 H 28 F 4 N 4 O 4 and a molecular weight of 572.55.
FDA label, Description section
Boxed warning
None in the current label
How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation.
Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)?
That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.
Causality screen of the 40 strongest signals
Labeled adverse reaction 1Labeled (related wording) 3Likely indication confounding 1Reporting / coding artifact 6Not in label — unassessed 29
What the badges mean
- 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.
- 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. 56 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Cytomegalovirus infection | 171 | 69.8 60.3–80.8ROR 73.8 · χ² 11,413 / p <1e-300 | 68.6 EB05 60.4 · IC025 +5.6 3/3 methods agree | Likely indication confounding term in indications | serious PRR 48.3 | no trial data cached |
| Nephropathy toxic | 80 | 48.6 39.1–60.4ROR 49.9 · χ² 3,657 / p <1e-300 | 47.7 EB05 39.6 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious PRR 34.7 · ♀ 22% (drug 43%) · 95% clinician | no trial data cached |
| Generalised oedema | 69 | 37.9 30.0–47.8ROR 38.7 · χ² 2,427 / p <1e-300 | 37.3 EB05 30.5 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious PRR 29.4 · ♀ 5% (drug 43%) · 94% clinician | no trial data cached |
| Thrombotic microangiopathy | 38 | 26.5 19.3–36.3ROR 26.8 · χ² 902 / p 2e-198 | 26.1 EB05 19.8 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious PRR 18.5 | no trial data cached |
| Drug resistance | 96 | 25.2 20.7–30.7ROR 26.0 · χ² 2,201 / p <1e-300 | 25.0 EB05 21.1 · IC025 +4.1 3/3 methods agree | Reporting / coding artifact | serious PRR 17.8 · 94% clinician | no trial data cached |
| Oesophagitis | 34 | 20.9 15.0–29.3ROR 21.2 · χ² 624 / p 4e-138 | 20.7 EB05 15.4 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious PRR 16.3 · ♀ 6% (drug 43%) · 100% clinician | no trial data cached |
| Respiratory distress | 79 | 19.3 15.5–24.0ROR 19.7 · χ² 1,348 / p 2e-295 | 19.1 EB05 15.8 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious PRR 13.7 · ♀ 8% (drug 43%) · 94% clinician | no trial data cached |
| Drug level increased | 45 | 18.3 13.7–24.5ROR 18.6 · χ² 717 / p 3e-158 | 18.1 EB05 14.0 · IC025 +3.4 3/3 methods agree | Reporting / coding artifact | serious PRR 13.3 · 93% clinician | no trial data cached |
| Pancytopenia (all blood cells low) | 148 | 17.9 15.3–20.9ROR 18.7 · χ² 2,343 / p <1e-300 | 17.8 EB05 15.5 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious PRR 12.6 · 94% clinician | no trial data cached |
| Myelosuppression | 87 | 17.2 14.0–21.2ROR 17.7 · χ² 1,312 / p 1e-287 | 17.1 EB05 14.3 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious PRR 12.1 · ♀ 21% (drug 43%) · 91% clinician | no trial data cached |
| Mucosal inflammation | 60 | 15.5 12.1–19.9ROR 15.8 · χ² 799 / p 5e-176 | 15.4 EB05 12.3 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious PRR 11.6 · 93% clinician | no trial data cached |
| Transfusion | 20 | 12.8 8.3–19.8ROR 12.9 · χ² 206 / p 6e-47 | 12.0 EB05 7.7 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 9.4 · ♀ 85% (drug 43%) · 90% clinician | no trial data cached |
| Pneumocystis jirovecii pneumonia | 19 | 12.8 8.2–20.0ROR 12.9 · χ² 195 / p 2e-44 | 11.9 EB05 7.6 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 9.0 | no trial data cached |
| Bacteraemia | 22 | 12.6 8.3–19.1ROR 12.7 · χ² 223 / p 1e-50 | 11.8 EB05 7.8 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 8.9 · 91% clinician | no trial data cached |
| Posterior reversible encephalopathy syndrome | 16 | 11.3 6.9–18.4ROR 11.4 · χ² 140 / p 1e-32 | 10.1 EB05 6.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 7.9 | no trial data cached |
| Acute myeloid leukaemia | 26 | 11.2 7.7–16.5ROR 11.3 · χ² 232 / p 1e-52 | 10.5 EB05 7.2 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 7.9 | no trial data cached |
| Drug level decreased | 16 | 10.5 6.5–17.2ROR 10.6 · χ² 128 / p 5e-30 | 9.2 EB05 5.6 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 9.1 | no trial data cached |
| Lung disorder | 72 | 9.9 7.9–12.4ROR 10.1 · χ² 567 / p 1e-125 | 9.6 EB05 7.8 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 7.6 · ♀ 11% (drug 43%) | no trial data cached |
| Acute respiratory distress syndrome | 25 | 9.5 6.4–14.0ROR 9.6 · χ² 182 / p 1e-41 | 8.7 EB05 6.0 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.7 · ♀ 86% (drug 43%) | no trial data cached |
| Multiple organ dysfunction syndrome | 39 | 9.4 6.9–12.8ROR 9.5 · χ² 284 / p 4e-64 | 8.9 EB05 6.6 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 6.6 · ♀ 69% (drug 43%) | no trial data cached |
| Septic shock | 60 | 9.3 7.3–12.0ROR 9.5 · χ² 439 / p 1e-97 | 9.0 EB05 7.2 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.6 · 97% clinician | no trial data cached |
| Cytopenia | 16 | 9.0 5.5–14.7ROR 9.0 · χ² 106 / p 4e-25 | 7.7 EB05 4.8 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 6.5 | no trial data cached |
| Lymphopenia | 18 | 8.6 5.4–13.6ROR 8.6 · χ² 113 / p 9e-27 | 7.5 EB05 4.8 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 6.5 | no trial data cached |
| Febrile neutropenia | 78 | 7.9 6.4–9.9ROR 8.1 · χ² 466 / p 1e-103 | 7.6 EB05 6.3 · IC025 +2.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.6 · 96% clinician | no trial data cached |
| Leukopenia (low white blood cells) | 57 | 7.7 5.9–9.9ROR 7.8 · χ² 325 / p 6e-73 | 7.3 EB05 5.8 · IC025 +2.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.4 · 91% clinician | no trial data cached |
| Acute kidney injury (sudden kidney damage) | 170 | 7.5 6.5–8.7ROR 7.9 · χ² 958 / p 1e-210 | 7.4 EB05 6.5 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.3 · ♀ 18% (drug 43%) · 92% clinician | no trial data cached |
| Status epilepticus | 12 | 7.1 4.1–12.5ROR 7.2 · χ² 57 / p 2e-14 | 5.8 EB05 3.5 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 5.0 | no trial data cached |
| Drug interaction | 165 | 7.0 6.0–8.1ROR 7.3 · χ² 847 / p 2e-186 | 6.9 EB05 6.0 · IC025 +2.5 3/3 methods agree | Reporting / coding artifact | serious PRR 4.8 · 92% clinician | no trial data cached |
| Product prescribing issue | 21 | 6.9 4.5–10.6ROR 7.0 · χ² 101 / p 5e-24 | 6.1 EB05 4.2 · IC025 +1.9 3/3 methods agree | Reporting / coding artifact | serious PRR 7.3 · 100% clinician | no trial data cached |
| Encephalopathy | 24 | 6.6 4.4–9.8ROR 6.6 · χ² 108 / p 1e-25 | 5.9 EB05 4.2 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 4.6 | no trial data cached |
| Agranulocytosis (severe loss of white cells) | 17 | 6.2 3.8–9.9ROR 6.2 · χ² 69 / p 6e-17 | 5.4 EB05 3.5 · IC025 +1.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.3 | no trial data cached |
| Altered state of consciousness | 19 | 5.9 3.8–9.3ROR 6.0 · χ² 73 / p 7e-18 | 5.2 EB05 3.5 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 | no trial data cached |
| Hepatic failure | 26 | 5.8 3.9–8.5ROR 5.8 · χ² 98 / p 2e-23 | 5.3 EB05 3.8 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 4.1 · ♀ 12% (drug 43%) | no trial data cached |
| Acute respiratory failure | 16 | 5.6 3.4–9.2ROR 5.6 · χ² 56 / p 3e-14 | 4.9 EB05 3.2 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 4.0 | no trial data cached |
| Hepatic cytolysis | 10 | 5.5 3.0–10.2ROR 5.5 · χ² 32 / p 6e-9 | 4.5 EB05 2.6 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.9 | no trial data cached |
| Immunodeficiency | 12 | 5.5 3.1–9.6ROR 5.5 · χ² 40 / p 2e-10 | 4.6 EB05 2.8 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 | no trial data cached |
| Pancreatitis acute | 18 | 5.4 3.4–8.6ROR 5.4 · χ² 61 / p 3e-15 | 4.8 EB05 3.2 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 | no trial data cached |
| Off label use (used outside approved label) | 689 | 5.3 5.0–5.7ROR 6.6 · χ² 2,527 / p <1e-300 | 5.3 EB05 5.0 · IC025 +2.3 3/3 methods agree | Reporting / coding artifact | serious PRR 5.1 | no trial data cached |
| Cytokine release syndrome | 15 | 5.3 3.2–8.8ROR 5.3 · χ² 48 / p 2e-12 | 4.6 EB05 3.0 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 | no trial data cached |
| Fungal infection | 23 | 4.6 3.1–7.0ROR 4.7 · χ² 62 / p 2e-15 | 4.3 EB05 3.0 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.0 | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).
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 |
|---|---|---|---|---|---|---|
| Off label use (used outside approved label) | 689 | 5.3 5.0–5.7ROR 6.6 · χ² 2,527 / p <1e-300 | 5.3 EB05 5.0 · IC025 +2.3 3/3 methods agree | Reporting / coding artifact | serious PRR 5.1 | no trial data cached |
| Cytomegalovirus infection | 171 | 69.8 60.3–80.8ROR 73.8 · χ² 11,413 / p <1e-300 | 68.6 EB05 60.4 · IC025 +5.6 3/3 methods agree | Likely indication confounding term in indications | serious PRR 48.3 | no trial data cached |
| Acute kidney injury (sudden kidney damage) | 170 | 7.5 6.5–8.7ROR 7.9 · χ² 958 / p 1e-210 | 7.4 EB05 6.5 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.3 · ♀ 18% (drug 43%) · 92% clinician | no trial data cached |
| Drug interaction | 165 | 7.0 6.0–8.1ROR 7.3 · χ² 847 / p 2e-186 | 6.9 EB05 6.0 · IC025 +2.5 3/3 methods agree | Reporting / coding artifact | serious PRR 4.8 · 92% clinician | no trial data cached |
| Product use in unapproved indication | 158 | 4.3 3.7–5.1ROR 4.5 · χ² 408 / p 4e-91 | 4.3 EB05 3.8 · IC025 +1.8 3/3 methods agree | Reporting / coding artifact | serious PRR 4.2 | no trial data cached |
| Pancytopenia (all blood cells low) | 148 | 17.9 15.3–20.9ROR 18.7 · χ² 2,343 / p <1e-300 | 17.8 EB05 15.5 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious PRR 12.6 · 94% clinician | no trial data cached |
| Drug resistance | 96 | 25.2 20.7–30.7ROR 26.0 · χ² 2,201 / p <1e-300 | 25.0 EB05 21.1 · IC025 +4.1 3/3 methods agree | Reporting / coding artifact | serious PRR 17.8 · 94% clinician | no trial data cached |
| Hospitalisation | 95 | 4.2 3.4–5.1ROR 4.3 · χ² 229 / p 5e-52 | 4.1 EB05 3.5 · IC025 +1.7 3/3 methods agree | Reporting / coding artifact | serious PRR 2.9 | no trial data cached |
| Product dose omission issue | 90 | 2.1 1.7–2.6ROR 2.2 · χ² 53 / p 2e-13 | 2.1 EB05 1.8 · IC025 +0.7 | Reporting / coding artifact | serious PRR 1.8 | no trial data cached |
| Myelosuppression | 87 | 17.2 14.0–21.2ROR 17.7 · χ² 1,312 / p 1e-287 | 17.1 EB05 14.3 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious PRR 12.1 · ♀ 21% (drug 43%) · 91% clinician | no trial data cached |
| No adverse event | 83 | 3.1 2.5–3.9ROR 3.2 · χ² 120 / p 3e-28 | 3.1 EB05 2.6 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious PRR 1.7 | no trial data cached |
| Nephropathy toxic | 80 | 48.6 39.1–60.4ROR 49.9 · χ² 3,657 / p <1e-300 | 47.7 EB05 39.6 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious PRR 34.7 · ♀ 22% (drug 43%) · 95% clinician | no trial data cached |
| Neutropenia (low neutrophils (infection-fighting cells)) | 79 | 3.9 3.2–4.9ROR 4.0 · χ² 170 / p 4e-39 | 3.8 EB05 3.2 · IC025 +1.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.9 · 91% clinician | no trial data cached |
| Respiratory distress | 79 | 19.3 15.5–24.0ROR 19.7 · χ² 1,348 / p 2e-295 | 19.1 EB05 15.8 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious PRR 13.7 · ♀ 8% (drug 43%) · 94% clinician | no trial data cached |
| Febrile neutropenia | 78 | 7.9 6.4–9.9ROR 8.1 · χ² 466 / p 1e-103 | 7.6 EB05 6.3 · IC025 +2.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.6 · 96% clinician | 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.
- Nephropathy toxic — n=80, PRR 48.6
- Generalised oedema — n=69, PRR 37.9
- Thrombotic microangiopathy — n=38, PRR 26.5
- Oesophagitis — n=34, PRR 20.9
- Respiratory distress — n=79, PRR 19.3
- Pancytopenia — n=148, PRR 17.9
- Myelosuppression — n=87, PRR 17.2
- Mucosal inflammation — n=60, PRR 15.5
- Transfusion — n=20, PRR 12.8
- Bacteraemia — n=22, PRR 12.6
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 Letermovir?
In FDA FAERS, the most frequently co-reported reaction terms for Letermovir are cytomegalovirus infection, acute kidney injury, pancytopenia, myelosuppression, nephropathy toxic, neutropenia. 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 Letermovir have an FDA boxed warning?
No. The FDA label retrieved for Letermovir has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Letermovir 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 1b49df80-be4f-47e0-a0b7-123f3e69395b, effective 20260114; matched on
openfda.generic_name.exact:"LETERMOVIR") - 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, 96 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.