Fosnetupitant and Palonosetron side effects: what 1,137 FDA adverse event reports show

Fosnetupitant And Palonosetron · Akynzeo · 23 reaction terms · 369 drug–reaction co-reports · data 2026-09-14

Drug class

Serotonin-3 Receptor Antagonist, Substance P/Neurokinin-1 Receptor Antagonist

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Akynzeo

openFDA label

Who reports

1,137 reports · 93% serious · 159 with death outcome · 63% female

openFDA FAERS counts, all years, deduplication not applied

Used for

AKYNZEO capsules is indicated in combination with dexamethasone in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of cancer chemotherapy, including, but not limited to, highly emetogenic chemotherapy.

FDA label, Indications and Usage

What it is

AKYNZEO (300 mg netupitant/0.5 mg palonosetron) capsules are an oral combination product of netupitant, a substance P/neurokinin 1 (NK-1) receptor antagonist, and palonosetron hydrochloride, a serotonin-3 (5-HT 3 ) receptor antagonist.

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 20 strongest signals

Labeled adverse reaction 1Lab value / disease marker 1Not in label — unassessed 18

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.
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. 3 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
Pneumocystis jirovecii pneumonia	12	22.2 12.6–38.9ROR 22.4 · χ² 222 / p 2e-50	21.3 EB05 12.6 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 13.7	no trial data cached
Inappropriate antidiuretic hormone secretion	8	14.5 7.3–28.9ROR 14.6 · χ² 88 / p 4e-21	12.0 EB05 5.4 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious PRR 9.0	no trial data cached
Hospice care	7	13.1 6.3–27.5ROR 13.2 · χ² 67 / p 2e-16	10.1 EB05 4.3 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 5.0	no trial data cached
Febrile neutropenia	47	13.1 9.9–17.3ROR 13.6 · χ² 514 / p 4e-114	12.9 EB05 9.9 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 8.1 · 100% clinician	no trial data cached
Neutropenia (low neutrophils (infection-fighting cells))	85	11.6 9.4–14.2ROR 12.4 · χ² 816 / p 1e-179	11.4 EB05 9.4 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 7.3 · 98% clinician	no trial data cached
Stomatitis (mouth sores)	38	11.6 8.5–15.8ROR 11.9 · χ² 357 / p 7e-80	11.1 EB05 8.3 · IC025 +2.8 3/3 methods agree	Not in label — unassessed	serious PRR 10.7	no trial data cached
Hypomagnesaemia	8	10.6 5.3–21.2ROR 10.7 · χ² 61 / p 4e-15	8.0 EB05 3.9 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 6.8	no trial data cached
Blood thyroid stimulating hormone increased	5	10.0 4.2–24.0ROR 10.0 · χ² 32 / p 8e-9	6.3 EB05 2.7 · IC025 +0.9 3/3 methods agree	Lab value / disease marker	serious n=5	no trial data cached
Leukopenia (low white blood cells)	27	10.0 6.9–14.5ROR 10.2 · χ² 210 / p 8e-48	9.2 EB05 6.4 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious PRR 6.4 · 100% clinician	no trial data cached
Mucosal inflammation	14	9.9 5.9–16.7ROR 10.0 · χ² 104 / p 1e-24	8.4 EB05 5.0 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 6.5	no trial data cached
Polyneuropathy	6	9.3 4.2–20.7ROR 9.3 · χ² 37 / p 7e-10	6.3 EB05 2.9 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 5.8	no trial data cached
Bone marrow failure	10	9.0 4.9–16.7ROR 9.1 · χ² 64 / p 8e-16	7.1 EB05 3.9 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 5.6	no trial data cached
Dermatitis	9	8.0 4.2–15.4ROR 8.1 · χ² 48 / p 2e-12	6.1 EB05 3.3 · IC025 +1.4 3/3 methods agree	Not in label — unassessed	serious PRR 10.1	no trial data cached
Cytokine release syndrome	8	7.7 3.9–15.5ROR 7.8 · χ² 41 / p 1e-10	5.7 EB05 3.0 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.8	no trial data cached
Hepatic cytolysis	5	7.5 3.1–18.1ROR 7.6 · χ² 22 / p 1e-6	4.9 EB05 2.2 · IC025 +0.7 3/3 methods agree	Not in label — unassessed	serious PRR 4.7	no trial data cached
Flushing	39	7.0 5.2–9.6ROR 7.3 · χ² 197 / p 4e-45	6.6 EB05 5.0 · IC025 +2.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 11.0 · 95% clinician	no trial data cached
Pneumonitis	10	6.8 3.7–12.6ROR 6.9 · χ² 44 / p 2e-11	5.4 EB05 3.1 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.4	no trial data cached
Cardiovascular disorder	7	5.0 2.4–10.6ROR 5.1 · χ² 19 / p 7e-6	3.9 EB05 2.1 · IC025 +0.7 3/3 methods agree	Not in label — unassessed	serious PRR 3.4	no trial data cached
Plasma cell myeloma	8	3.8 1.9–7.5ROR 3.8 · χ² 14 / p 1e-4	3.2 EB05 1.8 · IC025 +0.5	Not in label — unassessed	serious PRR 1.3	no trial data cached
Pancreatic carcinoma	5	3.2 1.3–7.6ROR 3.2 · χ² 5 / p 0.010	2.6 EB05 1.3 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Not in label — unassessed	serious PRR 2.0	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
Neutropenia (low neutrophils (infection-fighting cells))	85	11.6 9.4–14.2ROR 12.4 · χ² 816 / p 1e-179	11.4 EB05 9.4 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 7.3 · 98% clinician	no trial data cached
Febrile neutropenia	47	13.1 9.9–17.3ROR 13.6 · χ² 514 / p 4e-114	12.9 EB05 9.9 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 8.1 · 100% clinician	no trial data cached
Flushing	39	7.0 5.2–9.6ROR 7.3 · χ² 197 / p 4e-45	6.6 EB05 5.0 · IC025 +2.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 11.0 · 95% clinician	no trial data cached
Stomatitis (mouth sores)	38	11.6 8.5–15.8ROR 11.9 · χ² 357 / p 7e-80	11.1 EB05 8.3 · IC025 +2.8 3/3 methods agree	Not in label — unassessed	serious PRR 10.7	no trial data cached
Leukopenia (low white blood cells)	27	10.0 6.9–14.5ROR 10.2 · χ² 210 / p 8e-48	9.2 EB05 6.4 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious PRR 6.4 · 100% clinician	no trial data cached
Mucosal inflammation	14	9.9 5.9–16.7ROR 10.0 · χ² 104 / p 1e-24	8.4 EB05 5.0 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 6.5	no trial data cached
Pneumocystis jirovecii pneumonia	12	22.2 12.6–38.9ROR 22.4 · χ² 222 / p 2e-50	21.3 EB05 12.6 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 13.7	no trial data cached
Pneumonitis	10	6.8 3.7–12.6ROR 6.9 · χ² 44 / p 2e-11	5.4 EB05 3.1 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.4	no trial data cached
Bone marrow failure	10	9.0 4.9–16.7ROR 9.1 · χ² 64 / p 8e-16	7.1 EB05 3.9 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 5.6	no trial data cached
Dermatitis	9	8.0 4.2–15.4ROR 8.1 · χ² 48 / p 2e-12	6.1 EB05 3.3 · IC025 +1.4 3/3 methods agree	Not in label — unassessed	serious PRR 10.1	no trial data cached
Plasma cell myeloma	8	3.8 1.9–7.5ROR 3.8 · χ² 14 / p 1e-4	3.2 EB05 1.8 · IC025 +0.5	Not in label — unassessed	serious PRR 1.3	no trial data cached
Cytokine release syndrome	8	7.7 3.9–15.5ROR 7.8 · χ² 41 / p 1e-10	5.7 EB05 3.0 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.8	no trial data cached
Hypomagnesaemia	8	10.6 5.3–21.2ROR 10.7 · χ² 61 / p 4e-15	8.0 EB05 3.9 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 6.8	no trial data cached
Inappropriate antidiuretic hormone secretion	8	14.5 7.3–28.9ROR 14.6 · χ² 88 / p 4e-21	12.0 EB05 5.4 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious PRR 9.0	no trial data cached
Cardiovascular disorder	7	5.0 2.4–10.6ROR 5.1 · χ² 19 / p 7e-6	3.9 EB05 2.1 · IC025 +0.7 3/3 methods agree	Not in label — unassessed	serious PRR 3.4	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.

Febrile neutropenia — n=47, PRR 13.1
Neutropenia — n=85, PRR 11.6
Stomatitis — n=38, PRR 11.6
Leukopenia — n=27, PRR 10.0

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 Fosnetupitant and Palonosetron?

In FDA FAERS, the most frequently co-reported reaction terms for Fosnetupitant and Palonosetron are neutropenia, febrile neutropenia, flushing, stomatitis, leukopenia, mucosal inflammation. 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 Fosnetupitant and Palonosetron have an FDA boxed warning?

No. The FDA label retrieved for Fosnetupitant and Palonosetron has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Fosnetupitant and Palonosetron 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 8e47618e-af46-4d82-94e8-1507c042252d, effective 20260623; matched on openfda.generic_name.exact:"FOSNETUPITANT AND PALONOSETRON")
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, 23 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.