Drug · FAERS side-effect profile with label screen

Fedratinib side effects: what 1,320 FDA adverse event reports show

Fedratinib Hydrochloride · 13 reaction terms · 272 drug–reaction co-reports · data 2026-09-14

Drug class

Kinase inhibitor

FDA label, Indications wording of the closest related product

Label matched

Fedratinib Hydrochloride (Inrebic)

closest FDA label found for this product string; brand list suppressed because the label is a related product, not an exact match

Who reports

1,320 reports · 51% serious · 189 with death outcome · 49% female

openFDA FAERS counts, all years, deduplication not applied

Used for

INREBIC ® is indicated for the treatment of adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis (MF). INREBIC is a kinase inhibitor indicated for the treatment of adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis (MF) ( 1 ).

FDA label, Indications and Usage

What it is

INREBIC (fedratinib) is a kinase inhibitor with the chemical name N-tert-butyl-3-[(5-methyl-2-{[4-(2-pyrrolidin-1-ylethoxy)phenyl]amino}pyrimidin-4-yl)amino]benzenesulfonamide dihydrochloride monohydrate.

FDA label, Description section

Boxed warning

ENCEPHALOPATHY INCLUDING WERNICKE'S Serious and fatal encephalopathy, including Wernicke's, has occurred in patients treated with INREBIC. Wernicke's encephalopathy is a neurologic emergency. Assess thiamine levels in all patients prior to starting INREBIC.

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 11 strongest signals

Labeled — boxed warning 3Labeled adverse reaction 1Lab value / disease marker 5Not in label — unassessed 2

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.
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. 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
Splenomegaly	27	36.7 25.2–53.3ROR 37.4 · χ² 900 / p 6e-198	35.7 EB05 25.8 · IC025 +3.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 20.7	no trial data cached
Full blood count decreased	45	35.5 26.6–47.3ROR 36.7 · χ² 1,471 / p <1e-300	34.9 EB05 27.2 · IC025 +4.2 3/3 methods agree	Lab value / disease marker	serious PRR 41.2	no trial data cached
Full blood count abnormal	9	13.5 7.1–26.0ROR 13.6 · χ² 92 / p 4e-22	11.4 EB05 5.4 · IC025 +1.9 3/3 methods agree	Lab value / disease marker	serious PRR 9.1	no trial data cached
Red blood cell count decreased	23	12.8 8.5–19.1ROR 13.0 · χ² 238 / p 7e-54	12.1 EB05 8.1 · IC025 +2.7 3/3 methods agree	Lab value / disease marker	serious PRR 12.4	no trial data cached
White blood cell count increased	27	11.1 7.7–16.2ROR 11.3 · χ² 239 / p 3e-54	10.4 EB05 7.3 · IC025 +2.6 3/3 methods agree	Lab value / disease marker	serious PRR 9.5	no trial data cached
Platelet count increased	8	9.7 4.9–19.4ROR 9.8 · χ² 54 / p 9e-14	7.2 EB05 3.6 · IC025 +1.5 3/3 methods agree	Lab value / disease marker	serious PRR 12.7	no trial data cached
Hypocalcaemia (low calcium)	11	9.2 5.1–16.7ROR 9.3 · χ² 73 / p 7e-18	7.4 EB05 4.2 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 11.1	no trial data cached
Haemoglobin decreased	54	8.3 6.4–10.8ROR 8.6 · χ² 342 / p 1e-76	7.9 EB05 6.3 · IC025 +2.5 3/3 methods agree	Labeled — boxed warning synonym match	serious PRR 6.9	no trial data cached
Hepatic cytolysis	6	7.8 3.5–17.3ROR 7.8 · χ² 29 / p 4e-8	5.3 EB05 2.6 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 8.8	no trial data cached
Platelet count decreased	49	7.3 5.5–9.6ROR 7.5 · χ² 261 / p 4e-59	6.9 EB05 5.4 · IC025 +2.3 3/3 methods agree	Labeled — boxed warning synonym match	serious PRR 5.6	no trial data cached
Uveitis	5	5.9 2.4–14.1ROR 5.9 · χ² 16 / p 4e-5	4.1 EB05 1.9 · IC025 +0.5	Labeled — boxed warning exact term	serious PRR 7.1	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
Haemoglobin decreased	54	8.3 6.4–10.8ROR 8.6 · χ² 342 / p 1e-76	7.9 EB05 6.3 · IC025 +2.5 3/3 methods agree	Labeled — boxed warning synonym match	serious PRR 6.9	no trial data cached
Platelet count decreased	49	7.3 5.5–9.6ROR 7.5 · χ² 261 / p 4e-59	6.9 EB05 5.4 · IC025 +2.3 3/3 methods agree	Labeled — boxed warning synonym match	serious PRR 5.6	no trial data cached
Full blood count decreased	45	35.5 26.6–47.3ROR 36.7 · χ² 1,471 / p <1e-300	34.9 EB05 27.2 · IC025 +4.2 3/3 methods agree	Lab value / disease marker	serious PRR 41.2	no trial data cached
White blood cell count increased	27	11.1 7.7–16.2ROR 11.3 · χ² 239 / p 3e-54	10.4 EB05 7.3 · IC025 +2.6 3/3 methods agree	Lab value / disease marker	serious PRR 9.5	no trial data cached
Splenomegaly	27	36.7 25.2–53.3ROR 37.4 · χ² 900 / p 6e-198	35.7 EB05 25.8 · IC025 +3.8 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 20.7	no trial data cached
Red blood cell count decreased	23	12.8 8.5–19.1ROR 13.0 · χ² 238 / p 7e-54	12.1 EB05 8.1 · IC025 +2.7 3/3 methods agree	Lab value / disease marker	serious PRR 12.4	no trial data cached
Hypocalcaemia (low calcium)	11	9.2 5.1–16.7ROR 9.3 · χ² 73 / p 7e-18	7.4 EB05 4.2 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 11.1	no trial data cached
Full blood count abnormal	9	13.5 7.1–26.0ROR 13.6 · χ² 92 / p 4e-22	11.4 EB05 5.4 · IC025 +1.9 3/3 methods agree	Lab value / disease marker	serious PRR 9.1	no trial data cached
Platelet count increased	8	9.7 4.9–19.4ROR 9.8 · χ² 54 / p 9e-14	7.2 EB05 3.6 · IC025 +1.5 3/3 methods agree	Lab value / disease marker	serious PRR 12.7	no trial data cached
Hepatic cytolysis	6	7.8 3.5–17.3ROR 7.8 · χ² 29 / p 4e-8	5.3 EB05 2.6 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 8.8	no trial data cached
Uveitis	5	5.9 2.4–14.1ROR 5.9 · χ² 16 / p 4e-5	4.1 EB05 1.9 · IC025 +0.5	Labeled — boxed warning exact term	serious PRR 7.1	no trial data cached
Acute myeloid leukaemia	4	4.1 1.5–10.8ROR 4.1 · χ² 6 / p 0.006	3.0 EB05 1.3 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Not in label — unassessed	serious PRR 4.6	no trial data cached
Blood count abnormal	4	4.1 1.6–11.0ROR 4.1 · χ² 7 / p 0.005	3.0 EB05 1.4 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Lab value / disease marker	serious PRR 3.3	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 Fedratinib?

In FDA FAERS, the most frequently co-reported reaction terms for Fedratinib are haemoglobin decreased, platelet count decreased, full blood count decreased, white blood cell count increased, splenomegaly, red blood cell count decreased. 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 Fedratinib have an FDA boxed warning?

Yes. The current FDA label carries a boxed warning: ENCEPHALOPATHY INCLUDING WERNICKE'S Serious and fatal encephalopathy, including Wernicke's, has occurred in patients treated with INREBIC. Wernicke's encephalopathy is a neurologic emergency. Assess thiamine levels in all patients prior to starting INREBIC.

Do FAERS signals prove that Fedratinib 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 f0f55a2a-4e0c-4cba-8571-03e1424486d7, effective 20260720; matched on openfda.generic_name.exact:"FEDRATINIB HYDROCHLORIDE")
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, 13 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.