Natalizumab-Sztn side effects: what 221 FDA adverse event reports show

Natalizumab-Sztn · Tyruko · 4 reaction terms · 98 drug–reaction co-reports · data 2026-09-14

Drug class

Integrin Receptor Antagonist

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Tyruko

openFDA label

Who reports

221 reports · 96% serious · 4 with death outcome · 78% female

openFDA FAERS counts, all years, deduplication not applied

Used for

TYRUKO is an integrin receptor antagonist indicated for treatment of: Multiple Sclerosis (MS) TYRUKO is indicated as monotherapy for the treatment of relapsing forms of multiple sclerosis, to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease, in adults. Natalizumab products increase the risk of PML .

FDA label, Indications and Usage

What it is

Natalizumab-sztn is a recombinant humanized IgG4ĸ monoclonal antibody produced in a Chinese hamster ovary (CHO) mammalian cell expression system. Natalizumab-sztn contains human framework regions and the complementarity-determining regions of an antibody that binds to α4-integrin.

FDA label, Description section

Boxed warning

PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY Natalizumab products increase the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability.

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 4 strongest signals

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

What the badges mean

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. 0 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
Mobility decreased	53	70.3 55.6–88.9ROR 92.1 · χ² 3,559 / p <1e-300	68.6 EB05 54.4 · IC025 +5.0 3/3 methods agree	Not in label — unassessed	serious PRR 61.9 · 94% clinician	no trial data cached
Product substitution issue	21	34.6 23.1–52.0ROR 38.2 · χ² 654 / p 1e-144	33.7 EB05 23.2 · IC025 +3.5 3/3 methods agree	Reporting / coding artifact	serious PRR 41.9	no trial data cached
Multiple sclerosis relapse	16	22.0 13.7–35.2ROR 23.6 · χ² 300 / p 1e-67	21.4 EB05 13.8 · IC025 +2.9 3/3 methods agree	Labeled (related wording) related wording	serious PRR 18.2	no trial data cached
Multiple sclerosis	8	15.8 8.0–31.2ROR 16.3 · χ² 97 / p 4e-23	13.5 EB05 6.0 · IC025 +1.9 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 14.1	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
Mobility decreased	53	70.3 55.6–88.9ROR 92.1 · χ² 3,559 / p <1e-300	68.6 EB05 54.4 · IC025 +5.0 3/3 methods agree	Not in label — unassessed	serious PRR 61.9 · 94% clinician	no trial data cached
Product substitution issue	21	34.6 23.1–52.0ROR 38.2 · χ² 654 / p 1e-144	33.7 EB05 23.2 · IC025 +3.5 3/3 methods agree	Reporting / coding artifact	serious PRR 41.9	no trial data cached
Multiple sclerosis relapse	16	22.0 13.7–35.2ROR 23.6 · χ² 300 / p 1e-67	21.4 EB05 13.8 · IC025 +2.9 3/3 methods agree	Labeled (related wording) related wording	serious PRR 18.2	no trial data cached
Multiple sclerosis	8	15.8 8.0–31.2ROR 16.3 · χ² 97 / p 4e-23	13.5 EB05 6.0 · IC025 +1.9 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 14.1	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.

Mobility decreased — n=53, PRR 70.3

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 Natalizumab-Sztn?

In FDA FAERS, the most frequently co-reported reaction terms for Natalizumab-Sztn are mobility decreased, multiple sclerosis relapse, multiple sclerosis. 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 Natalizumab-Sztn have an FDA boxed warning?

Yes. The current FDA label carries a boxed warning: PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY Natalizumab products increase the risk of progressive multifocal leukoencephalopathy (PML), an opportunistic viral infection of the brain that usually leads to death or severe disability.

Do FAERS signals prove that Natalizumab-Sztn 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 ef653c36-dd4b-4e71-9d2d-40b8fea24b67, effective 20251031; matched on openfda.generic_name.exact:"NATALIZUMAB-SZTN")
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, 4 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.