Oxacillin side effects: what 965 FDA adverse event reports show

Oxacillin · 37 reaction terms · 519 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Who reports

965 reports · 94% serious · 187 with death outcome · 37% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Oxacillin is indicated in the treatment of infections caused by penicillinase producing staphylococci which have demonstrated susceptibility to the drug. Cultures and susceptibility tests should be performed initially to determine the causative organism and its susceptibility to the drug (see CLINICAL PHARMACOLOGY-Susceptibility Testing ).

FDA label, Indications and Usage

What it is

DESCRIPTION: Oxacillin for Injection, USP is a semisynthetic penicillin antibiotic derived from the penicillin nucleus, 6-amino-penicillanic acid. It is resistant to inactivation by the enzyme penicillinase (beta-lactamase). It is the sodium salt in parenteral dosage form for intramuscular or intravenous use.

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 23 strongest signals

Labeled adverse reaction 2Labeled (related wording) 1Likely indication confounding 2Reporting / coding artifact 4Not in label — unassessed 14

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. 14 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
Toxic epidermal necrolysis (severe skin peeling reaction)	32	46.2 32.9–65.0ROR 47.8 · χ² 1,368 / p 8e-300	45.0 EB05 33.3 · IC025 +4.2 3/3 methods agree	Not in label — unassessed	serious PRR 28.4 · 100% clinician	no trial data cached
Drug reaction with eosinophilia and systemic symptoms	54	46.0 35.5–59.6ROR 48.7 · χ² 2,331 / p <1e-300	45.2 EB05 36.0 · IC025 +4.6 3/3 methods agree	Labeled (related wording) related wording	serious PRR 28.3 · 100% clinician	no trial data cached
Renal tubular necrosis	17	37.6 23.5–60.3ROR 38.3 · χ² 569 / p 4e-126	36.2 EB05 23.9 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 23.3	no trial data cached
Toxic skin eruption	15	32.3 19.5–53.4ROR 32.8 · χ² 424 / p 2e-94	31.1 EB05 20.0 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 19.9	no trial data cached
Bacteraemia	17	31.4 19.6–50.4ROR 32.0 · χ² 470 / p 1e-104	30.4 EB05 20.1 · IC025 +3.3 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 19.5	no trial data cached
Eosinophilia	21	26.1 17.1–39.9ROR 26.7 · χ² 483 / p 3e-107	25.6 EB05 17.6 · IC025 +3.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 16.0 · 95% clinician	no trial data cached
Device related infection	18	25.4 16.1–40.1ROR 25.8 · χ² 397 / p 1e-88	24.7 EB05 16.5 · IC025 +3.1 3/3 methods agree	Reporting / coding artifact	serious PRR 16.0	no trial data cached
Staphylococcal infection	35	23.0 16.6–31.8ROR 23.8 · χ² 715 / p 9e-158	22.7 EB05 17.1 · IC025 +3.6 3/3 methods agree	Likely indication confounding term in indications	serious PRR 15.2 · 100% clinician	no trial data cached
Drug resistance	27	22.9 15.8–33.2ROR 23.5 · χ² 543 / p 2e-120	22.5 EB05 16.2 · IC025 +3.4 3/3 methods agree	Reporting / coding artifact	serious PRR 15.2 · 100% clinician	no trial data cached
Disseminated intravascular coagulation	13	20.0 11.7–34.4ROR 20.3 · χ² 216 / p 3e-49	19.2 EB05 11.5 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 12.3	no trial data cached
Cardiogenic shock	13	19.8 11.5–34.0ROR 20.1 · χ² 214 / p 1e-48	19.0 EB05 11.3 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 12.2	no trial data cached
Multi-organ failure	15	18.6 11.2–30.7ROR 18.9 · χ² 232 / p 9e-53	17.9 EB05 11.1 · IC025 +2.7 3/3 methods agree	Not in label — unassessed	serious PRR 11.4	no trial data cached
Drug level increased	11	14.4 8.0–26.0ROR 14.6 · χ² 124 / p 3e-29	12.9 EB05 6.7 · IC025 +2.2 3/3 methods agree	Reporting / coding artifact	serious PRR 9.8	no trial data cached
Renal failure acute	28	14.1 9.8–20.4ROR 14.5 · χ² 329 / p 6e-74	13.7 EB05 9.7 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 8.8 · 96% clinician	no trial data cached
Agranulocytosis (severe loss of white cells)	11	12.9 7.2–23.3ROR 13.1 · χ² 110 / p 6e-26	11.2 EB05 5.8 · IC025 +2.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.0	no trial data cached
Tubulointerstitial nephritis	11	12.8 7.1–23.0ROR 12.9 · χ² 108 / p 1e-25	11.0 EB05 5.8 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 7.2	no trial data cached
Liver injury	14	12.6 7.5–21.2ROR 12.8 · χ² 138 / p 4e-32	11.3 EB05 6.5 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 6.9	no trial data cached
Cholestasis (bile flow blockage)	10	11.4 6.1–21.1ROR 11.5 · χ² 85 / p 2e-20	9.3 EB05 4.8 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 7.1	no trial data cached
Lactic acidosis	15	10.2 6.1–16.8ROR 10.3 · χ² 115 / p 4e-27	8.8 EB05 5.3 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 6.3	no trial data cached
Rash maculo-papular	10	9.8 5.3–18.2ROR 9.9 · χ² 71 / p 2e-17	7.8 EB05 4.2 · IC025 +1.7 3/3 methods agree	Not in label — unassessed	serious PRR 6.7	no trial data cached
Premature baby	13	9.4 5.5–16.1ROR 9.5 · χ² 89 / p 2e-21	7.8 EB05 4.6 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 5.9	no trial data cached
Rhabdomyolysis (muscle breakdown)	16	8.4 5.1–13.6ROR 8.5 · χ² 97 / p 4e-23	7.1 EB05 4.5 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 5.2	no trial data cached
Foetal exposure during pregnancy	13	3.5 2.0–6.0ROR 3.5 · χ² 21 / p 3e-6	3.2 EB05 2.0 · IC025 +0.7	Reporting / coding artifact	serious PRR 2.2	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
Drug reaction with eosinophilia and systemic symptoms	54	46.0 35.5–59.6ROR 48.7 · χ² 2,331 / p <1e-300	45.2 EB05 36.0 · IC025 +4.6 3/3 methods agree	Labeled (related wording) related wording	serious PRR 28.3 · 100% clinician	no trial data cached
Staphylococcal infection	35	23.0 16.6–31.8ROR 23.8 · χ² 715 / p 9e-158	22.7 EB05 17.1 · IC025 +3.6 3/3 methods agree	Likely indication confounding term in indications	serious PRR 15.2 · 100% clinician	no trial data cached
Toxic epidermal necrolysis (severe skin peeling reaction)	32	46.2 32.9–65.0ROR 47.8 · χ² 1,368 / p 8e-300	45.0 EB05 33.3 · IC025 +4.2 3/3 methods agree	Not in label — unassessed	serious PRR 28.4 · 100% clinician	no trial data cached
Renal failure acute	28	14.1 9.8–20.4ROR 14.5 · χ² 329 / p 6e-74	13.7 EB05 9.7 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 8.8 · 96% clinician	no trial data cached
Drug resistance	27	22.9 15.8–33.2ROR 23.5 · χ² 543 / p 2e-120	22.5 EB05 16.2 · IC025 +3.4 3/3 methods agree	Reporting / coding artifact	serious PRR 15.2 · 100% clinician	no trial data cached
Eosinophilia	21	26.1 17.1–39.9ROR 26.7 · χ² 483 / p 3e-107	25.6 EB05 17.6 · IC025 +3.3 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 16.0 · 95% clinician	no trial data cached
Device related infection	18	25.4 16.1–40.1ROR 25.8 · χ² 397 / p 1e-88	24.7 EB05 16.5 · IC025 +3.1 3/3 methods agree	Reporting / coding artifact	serious PRR 16.0	no trial data cached
Bacteraemia	17	31.4 19.6–50.4ROR 32.0 · χ² 470 / p 1e-104	30.4 EB05 20.1 · IC025 +3.3 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious PRR 19.5	no trial data cached
Renal tubular necrosis	17	37.6 23.5–60.3ROR 38.3 · χ² 569 / p 4e-126	36.2 EB05 23.9 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 23.3	no trial data cached
Rhabdomyolysis (muscle breakdown)	16	8.4 5.1–13.6ROR 8.5 · χ² 97 / p 4e-23	7.1 EB05 4.5 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 5.2	no trial data cached
Lactic acidosis	15	10.2 6.1–16.8ROR 10.3 · χ² 115 / p 4e-27	8.8 EB05 5.3 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 6.3	no trial data cached
Multi-organ failure	15	18.6 11.2–30.7ROR 18.9 · χ² 232 / p 9e-53	17.9 EB05 11.1 · IC025 +2.7 3/3 methods agree	Not in label — unassessed	serious PRR 11.4	no trial data cached
Toxic skin eruption	15	32.3 19.5–53.4ROR 32.8 · χ² 424 / p 2e-94	31.1 EB05 20.0 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 19.9	no trial data cached
Liver injury	14	12.6 7.5–21.2ROR 12.8 · χ² 138 / p 4e-32	11.3 EB05 6.5 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 6.9	no trial data cached
Foetal exposure during pregnancy	13	3.5 2.0–6.0ROR 3.5 · χ² 21 / p 3e-6	3.2 EB05 2.0 · IC025 +0.7	Reporting / coding artifact	serious PRR 2.2	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.

Toxic epidermal necrolysis — n=32, PRR 46.2
Renal failure acute — n=28, PRR 14.1

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 Oxacillin?

In FDA FAERS, the most frequently co-reported reaction terms for Oxacillin are drug reaction with eosinophilia and systemic symptoms, staphylococcal infection, toxic epidermal necrolysis, renal failure acute, eosinophilia, bacteraemia. 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 Oxacillin have an FDA boxed warning?

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

Do FAERS signals prove that Oxacillin 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 af2dccac-98c8-488f-a133-6374b3ca8dba, effective 20200729; matched on openfda.generic_name.exact:"OXACILLIN")
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, 37 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.