Ontruzant side effects: what 522 FDA adverse event reports show

Ontruzant · 17 reaction terms · 174 drug–reaction co-reports · data 2026-09-14

Drug class

HER2/neu Receptor Antagonist

FDA label (Established Pharmacologic Class) · compare the class

Who reports

522 reports · 93% serious · 28 with death outcome · 78% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Ontruzant is a HER2/neu receptor antagonist indicated in adults for: The treatment of HER2-overexpressing breast cancer. ( 1.1 , 1.2 ) The treatment of HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma. ( 1.3 ) Select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product ( 1 , 2.2 ).

FDA label, Indications and Usage

What it is

Trastuzumab-dttb is a humanized IgG1 kappa monoclonal antibody that selectively binds with high affinity to the extracellular domain of the human epidermal growth factor receptor 2 protein, HER2. Trastuzumab-dttb is produced by recombinant DNA technology in a mammalian cell (Chinese Hamster Ovary) culture.

FDA label, Description section

Boxed warning

CARDIOMYOPATHY, INFUSION REACTIONS, EMBRYO-FETAL TOXICITY, and PULMONARY TOXICITY WARNING: CARDIOMYOPATHY, INFUSION REACTIONS, EMBRYO-FETAL TOXICITY, and PULMONARY TOXICITY See full prescribing information for comple.

FDA 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 15 strongest signals

Labeled adverse reaction 2Labeled (related wording) 2Likely indication confounding 1Reporting / coding artifact 1Not in label — unassessed 9

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. 2 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Polyneuropathy	18	60.9 38.6–95.9ROR 63.0 · χ² 1,000 / p 9e-220	57.3 EB05 38.3 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious PRR 35.9	no trial data cached
Hypomagnesaemia	14	40.6 24.2–68.0ROR 41.7 · χ² 501 / p 2e-111	38.6 EB05 24.4 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious PRR 25.8	no trial data cached
Ejection fraction decreased	15	38.7 23.5–63.8ROR 39.9 · χ² 514 / p 4e-114	37.0 EB05 23.8 · IC025 +3.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 26.4	no trial data cached
Hypokalaemia (low potassium)	44	38.5 29.0–51.2ROR 42.0 · χ² 1,574 / p <1e-300	37.9 EB05 29.4 · IC025 +4.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 24.2 · ♀ 100% (drug 78%) · 100% clinician	no trial data cached
Flank pain	6	25.8 11.6–57.1ROR 26.1 · χ² 119 / p 5e-28	22.8 EB05 9.4 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 20.9	no trial data cached
Device related infection	9	23.4 12.3–44.8ROR 23.8 · χ² 172 / p 2e-39	22.0 EB05 11.7 · IC025 +2.3 3/3 methods agree	Reporting / coding artifact	serious PRR 14.9	no trial data cached
Ileus	7	22.9 11.0–47.7ROR 23.2 · χ² 125 / p 2e-29	20.6 EB05 9.1 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 14.2	no trial data cached
Renal pain	6	22.8 10.3–50.6ROR 23.1 · χ² 104 / p 9e-25	19.9 EB05 7.6 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 20.8	no trial data cached
Hypertensive crisis	6	21.6 9.7–47.9ROR 21.8 · χ² 98 / p 2e-23	18.6 EB05 7.0 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 13.4	no trial data cached
Hepatic encephalopathy	5	21.5 9.0–51.5ROR 21.7 · χ² 78 / p 4e-19	17.3 EB05 5.5 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 13.3	no trial data cached
Conjunctivitis	9	19.7 10.3–37.6ROR 20.0 · χ² 142 / p 6e-33	18.2 EB05 9.0 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious PRR 20.1	no trial data cached
Gastric haemorrhage	5	17.3 7.2–41.5ROR 17.5 · χ² 62 / p 2e-15	12.9 EB05 4.2 · IC025 +1.2 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 11.1	no trial data cached
Cardiovascular disorder	10	15.7 8.5–29.0ROR 16.0 · χ² 124 / p 5e-29	14.1 EB05 7.0 · IC025 +2.1 3/3 methods agree	Labeled (related wording) related wording	serious PRR 10.4	no trial data cached
Palmar-plantar erythrodysaesthesia syndrome	7	12.0 5.8–25.1ROR 12.2 · χ² 60 / p 4e-15	9.0 EB05 4.0 · IC025 +1.5 3/3 methods agree	Not in label — unassessed	serious PRR 8.5	no trial data cached
Osteonecrosis of jaw (jawbone death)	7	11.3 5.4–23.6ROR 11.4 · χ² 56 / p 4e-14	8.3 EB05 3.8 · IC025 +1.4 3/3 methods agree	Not in label — unassessed	serious PRR 7.0	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
Hypokalaemia (low potassium)	44	38.5 29.0–51.2ROR 42.0 · χ² 1,574 / p <1e-300	37.9 EB05 29.4 · IC025 +4.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 24.2 · ♀ 100% (drug 78%) · 100% clinician	no trial data cached
Polyneuropathy	18	60.9 38.6–95.9ROR 63.0 · χ² 1,000 / p 9e-220	57.3 EB05 38.3 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious PRR 35.9	no trial data cached
Ejection fraction decreased	15	38.7 23.5–63.8ROR 39.9 · χ² 514 / p 4e-114	37.0 EB05 23.8 · IC025 +3.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 26.4	no trial data cached
Hypomagnesaemia	14	40.6 24.2–68.0ROR 41.7 · χ² 501 / p 2e-111	38.6 EB05 24.4 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious PRR 25.8	no trial data cached
Cardiovascular disorder	10	15.7 8.5–29.0ROR 16.0 · χ² 124 / p 5e-29	14.1 EB05 7.0 · IC025 +2.1 3/3 methods agree	Labeled (related wording) related wording	serious PRR 10.4	no trial data cached
Conjunctivitis	9	19.7 10.3–37.6ROR 20.0 · χ² 142 / p 6e-33	18.2 EB05 9.0 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious PRR 20.1	no trial data cached
Device related infection	9	23.4 12.3–44.8ROR 23.8 · χ² 172 / p 2e-39	22.0 EB05 11.7 · IC025 +2.3 3/3 methods agree	Reporting / coding artifact	serious PRR 14.9	no trial data cached
Osteonecrosis of jaw (jawbone death)	7	11.3 5.4–23.6ROR 11.4 · χ² 56 / p 4e-14	8.3 EB05 3.8 · IC025 +1.4 3/3 methods agree	Not in label — unassessed	serious PRR 7.0	no trial data cached
Palmar-plantar erythrodysaesthesia syndrome	7	12.0 5.8–25.1ROR 12.2 · χ² 60 / p 4e-15	9.0 EB05 4.0 · IC025 +1.5 3/3 methods agree	Not in label — unassessed	serious PRR 8.5	no trial data cached
Ileus	7	22.9 11.0–47.7ROR 23.2 · χ² 125 / p 2e-29	20.6 EB05 9.1 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 14.2	no trial data cached
Hypertensive crisis	6	21.6 9.7–47.9ROR 21.8 · χ² 98 / p 2e-23	18.6 EB05 7.0 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 13.4	no trial data cached
Renal pain	6	22.8 10.3–50.6ROR 23.1 · χ² 104 / p 9e-25	19.9 EB05 7.6 · IC025 +1.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 20.8	no trial data cached
Flank pain	6	25.8 11.6–57.1ROR 26.1 · χ² 119 / p 5e-28	22.8 EB05 9.4 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 20.9	no trial data cached
Gastric haemorrhage	5	17.3 7.2–41.5ROR 17.5 · χ² 62 / p 2e-15	12.9 EB05 4.2 · IC025 +1.2 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 11.1	no trial data cached
Hepatic encephalopathy	5	21.5 9.0–51.5ROR 21.7 · χ² 78 / p 4e-19	17.3 EB05 5.5 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 13.3	no trial data cached

Unlabeled candidate signals

Every screened signal with n ≥ 20 was either labeled, an indication term, or an artifact pattern — no unlabeled candidate stood out in the top signals.

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 Ontruzant?

In FDA FAERS, the most frequently co-reported reaction terms for Ontruzant are hypokalaemia, polyneuropathy, ejection fraction decreased, hypomagnesaemia, cardiovascular disorder, conjunctivitis. 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 Ontruzant have an FDA boxed warning?

Yes. The current FDA label carries a boxed warning: CARDIOMYOPATHY, INFUSION REACTIONS, EMBRYO-FETAL TOXICITY, and PULMONARY TOXICITY WARNING: CARDIOMYOPATHY, INFUSION REACTIONS, EMBRYO-FETAL TOXICITY, and PULMONARY TOXICITY See full prescribing information for comple.

Do FAERS signals prove that Ontruzant 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 ce2a2492-85e3-4b0a-872a-047f44e4203d, effective 20260420; matched on openfda.generic_name.exact:"ONTRUZANT")
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, field patient.drug.openfda.generic_name.exact, 17 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.