Drug · FAERS side-effect profile with label screen

Polymyxin B and Trimethoprim side effects: what 153 FDA adverse event reports show

Polymyxin B Sulfate And Trimethoprim Sulfate · 5 reaction terms · 89 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Label matched

Polymyxin B (Polymyxin B)

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

Who reports

153 reports · 32% serious · 3 with death outcome · 76% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Acute Infections Caused by Susceptible Strains of Pseudomonas aeruginosa. Polymyxin B sulfate is a drug of choice in the treatment of infections of the urinary tract, meninges, and bloodstream caused by susceptible strains of Ps. aeruginosa . It may also be used topically and subconjunctivally in the treatment of infections of the eye caused by susceptible strains of Ps. aeruginosa .

FDA label, Indications and Usage

What it is

DESCRIPTION Polymyxin B for Injection, USP is one of a group of basic polypeptide antibiotics derived from B polymyxa (B aerosporous) . Polymyxin B sulfate is the sulfate salt of Polymyxins B 1 and B 2 , which are produced by the growth of Bacillus polymyxa (Prazmowski) Migula (Fam. Bacillacea).

FDA label, Description section

Boxed warning

CAUTION: WHEN THIS DRUG IS GIVEN INTRAMUSCULARLY, INTRAVENOUSLY AND/OR INTRATHECALLY, IT SHOULD BE GIVEN ONLY TO HOSPITALIZED PATIENTS, SO AS TO PROVIDE CONSTANT SUPERVISION BY A PHYSICIAN. RENAL FUNCTION SHOULD BE CAREFULLY DETERMINED AND PATIENTS WITH RENAL DAMAGE AND NITROGEN RETENTION SHOULD HAVE REDUCED DOSAGE.

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 5 strongest signals

Labeled (related wording) 1Not in label — unassessed 4

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.
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
Eye discharge	10	134.3 73.7–244.5ROR 143.6 · χ² 1,192 / p 2e-261	107.3 EB05 62.3 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious n=1	no trial data cached
Eye pruritus	21	87.3 58.7–130.0ROR 101.1 · χ² 1,709 / p <1e-300	81.1 EB05 55.9 · IC025 +4.1 3/3 methods agree	Not in label — unassessed	serious PRR 55.5 · 100% consumer	no trial data cached
Eye swelling	18	66.8 43.2–103.0ROR 75.5 · χ² 1,102 / p 5e-242	62.5 EB05 41.8 · IC025 +3.8 3/3 methods agree	Not in label — unassessed	serious PRR 70.4	no trial data cached
Ocular hyperaemia	21	61.6 41.4–91.7ROR 71.3 · χ² 1,195 / p 4e-262	58.5 EB05 40.4 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious PRR 46.5 · 100% consumer	no trial data cached
Eye irritation	19	46.7 30.7–71.2ROR 53.2 · χ² 807 / p 9e-178	44.8 EB05 30.3 · IC025 +3.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 44.1	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
Ocular hyperaemia	21	61.6 41.4–91.7ROR 71.3 · χ² 1,195 / p 4e-262	58.5 EB05 40.4 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious PRR 46.5 · 100% consumer	no trial data cached
Eye pruritus	21	87.3 58.7–130.0ROR 101.1 · χ² 1,709 / p <1e-300	81.1 EB05 55.9 · IC025 +4.1 3/3 methods agree	Not in label — unassessed	serious PRR 55.5 · 100% consumer	no trial data cached
Eye irritation	19	46.7 30.7–71.2ROR 53.2 · χ² 807 / p 9e-178	44.8 EB05 30.3 · IC025 +3.7 3/3 methods agree	Labeled (related wording) related wording	serious PRR 44.1	no trial data cached
Eye swelling	18	66.8 43.2–103.0ROR 75.5 · χ² 1,102 / p 5e-242	62.5 EB05 41.8 · IC025 +3.8 3/3 methods agree	Not in label — unassessed	serious PRR 70.4	no trial data cached
Eye discharge	10	134.3 73.7–244.5ROR 143.6 · χ² 1,192 / p 2e-261	107.3 EB05 62.3 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious n=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.

Eye pruritus — n=21, PRR 87.3
Ocular hyperaemia — n=21, PRR 61.6

✓ A hand-written Bradford Hill causality assessment exists for this drug: Trimethoprim (and co-trimoxazole) ↔ Hyperkalaemia.

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 Polymyxin B and Trimethoprim?

In FDA FAERS, the most frequently co-reported reaction terms for Polymyxin B and Trimethoprim are ocular hyperaemia, eye pruritus, eye irritation, eye swelling, eye discharge. 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 Polymyxin B and Trimethoprim have an FDA boxed warning?

Yes. The current FDA label carries a boxed warning: CAUTION: WHEN THIS DRUG IS GIVEN INTRAMUSCULARLY, INTRAVENOUSLY AND/OR INTRATHECALLY, IT SHOULD BE GIVEN ONLY TO HOSPITALIZED PATIENTS, SO AS TO PROVIDE CONSTANT SUPERVISION BY A PHYSICIAN. RENAL FUNCTION SHOULD BE CAREFULLY DETERMINED AND PATIENTS WITH RENAL DAMAGE AND NITROGEN RETENTION SHOULD HAVE REDUCED DOSAGE.

Do FAERS signals prove that Polymyxin B and Trimethoprim 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 a974c557-e88f-451b-a1bd-d2c656be226e, effective 20250509; matched on openfda.generic_name.exact:"POLYMYXIN B")
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, 5 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.