Drug · FAERS side-effect profile with label screen
Cefaclor side effects: what 1,535 FDA adverse event reports show
Drug class
Not stated in label
Who reports
1,535 reports · 86% serious · 148 with death outcome · 63% female
openFDA FAERS counts, all years, deduplication not applied
Used for
To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefaclor extended-release tablets USP and other antibacterial drugs, cefaclor extended-release tablets USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria.
FDA label, Indications and Usage
What it is
DESCRIPTION Cefaclor, USP, the active ingredient in cefaclor extended-release tablets USP, is a semisynthetic cephalosporin antibiotic for oral administration. Cefaclor, USP, is chemically designated as 3-chloro-7-D(2-phenylglycinamido)-3-cephem-4-carboxylic acid monohydrate.
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 40 strongest signals
Labeled adverse reaction 4Labeled (related wording) 4Likely indication confounding 2Reporting / coding artifact 2Lab value / disease marker 3Not in label — unassessed 25
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.
- 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. 73 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Red blood cell sedimentation rate increased | 43 | 53.2 39.6–71.5ROR 54.7 · χ² 2,143 / p <1e-300 | 51.8 EB05 40.1 · IC025 +4.5 3/3 methods agree | Lab value / disease marker | serious PRR 40.0 · ♀ 100% (drug 63%) · 98% clinician | no trial data cached |
| Platelet count increased | 50 | 52.5 40.0–69.0ROR 54.2 · χ² 2,467 / p <1e-300 | 51.3 EB05 40.5 · IC025 +4.6 3/3 methods agree | Lab value / disease marker | serious PRR 45.9 · ♀ 94% (drug 63%) · 94% clinician | no trial data cached |
| Secretion discharge | 41 | 45.5 33.6–61.6ROR 46.7 · χ² 1,736 / p <1e-300 | 44.5 EB05 34.2 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious PRR 49.6 · ♀ 100% (drug 63%) · 95% clinician | no trial data cached |
| Toxic epidermal necrolysis (severe skin peeling reaction) | 40 | 36.3 26.8–49.4ROR 37.3 · χ² 1,337 / p 4e-293 | 35.7 EB05 27.3 · IC025 +4.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 24.1 · 92% clinician | no trial data cached |
| Eye inflammation | 22 | 31.9 21.1–48.4ROR 32.4 · χ² 628 / p 8e-139 | 31.1 EB05 21.7 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=22 · ♀ 100% (drug 63%) | no trial data cached |
| Clostridium difficile infection | 41 | 25.9 19.1–35.1ROR 26.6 · χ² 956 / p 3e-210 | 25.6 EB05 19.7 · IC025 +3.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 18.1 · ♀ 100% (drug 63%) | no trial data cached |
| Lymphocyte count decreased | 31 | 24.0 16.9–34.0ROR 24.5 · χ² 660 / p 8e-146 | 23.7 EB05 17.4 · IC025 +3.5 3/3 methods agree | Lab value / disease marker | serious PRR 19.5 · 100% clinician | no trial data cached |
| Paralysis | 24 | 22.9 15.4–34.0ROR 23.2 · χ² 480 / p 1e-106 | 22.5 EB05 15.8 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 15.8 · ♀ 100% (drug 63%) | no trial data cached |
| Skin infection | 18 | 22.1 13.9–35.0ROR 22.3 · χ² 341 / p 2e-76 | 21.5 EB05 14.3 · IC025 +3.0 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 20.3 | no trial data cached |
| Paraesthesia oral | 23 | 21.9 14.6–32.9ROR 22.2 · χ² 438 / p 2e-97 | 21.5 EB05 15.0 · IC025 +3.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 26.0 · ♀ 96% (drug 63%) | no trial data cached |
| Helicobacter infection | 16 | 21.5 13.2–35.0ROR 21.7 · χ² 292 / p 9e-66 | 20.9 EB05 13.4 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 15.1 | no trial data cached |
| Staphylococcal infection | 50 | 20.7 15.7–27.2ROR 21.3 · χ² 917 / p 1e-201 | 20.5 EB05 16.1 · IC025 +3.6 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 15.2 · ♀ 97% (drug 63%) · 94% clinician | no trial data cached |
| Drug eruption | 26 | 20.2 13.8–29.6ROR 20.5 · χ² 455 / p 3e-101 | 19.9 EB05 14.2 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious PRR 12.5 · ♀ 41% (drug 63%) | no trial data cached |
| Muscle tightness | 23 | 19.5 13.0–29.2ROR 19.7 · χ² 384 / p 7e-86 | 19.1 EB05 13.3 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious PRR 25.0 · ♀ 96% (drug 63%) | no trial data cached |
| Therapeutic product effect incomplete | 95 | 18.4 15.1–22.3ROR 19.5 · χ² 1,548 / p <1e-300 | 18.3 EB05 15.4 · IC025 +3.7 3/3 methods agree | Reporting / coding artifact | serious PRR 23.0 · ♀ 85% (drug 63%) · 95% clinician | no trial data cached |
| Obesity | 21 | 18.0 11.8–27.6ROR 18.2 · χ² 320 / p 6e-72 | 17.6 EB05 11.9 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 13.2 · ♀ 95% (drug 63%) | no trial data cached |
| Drug hypersensitivity | 252 | 17.8 15.9–19.9ROR 21.1 · χ² 4,000 / p <1e-300 | 17.7 EB05 16.0 · IC025 +3.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 18.1 · ♀ 91% (drug 63%) | no trial data cached |
| Pemphigus | 16 | 17.6 10.8–28.7ROR 17.8 · χ² 234 / p 4e-53 | 17.0 EB05 10.6 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 11.7 | no trial data cached |
| Erythema multiforme | 11 | 16.1 9.0–29.1ROR 16.3 · χ² 141 / p 7e-33 | 14.8 EB05 7.8 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 11.1 | no trial data cached |
| Liver injury | 28 | 15.8 11.0–22.9ROR 16.1 · χ² 375 / p 9e-84 | 15.5 EB05 11.1 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 10.9 · 93% clinician | no trial data cached |
| Iron deficiency anaemia | 10 | 14.9 8.0–27.6ROR 15.0 · χ² 116 / p 2e-27 | 13.2 EB05 6.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 10.5 | no trial data cached |
| End stage renal disease | 20 | 14.9 9.6–23.0ROR 15.0 · χ² 245 / p 2e-55 | 14.3 EB05 9.3 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 9.9 | no trial data cached |
| Hypocalcaemia (low calcium) | 20 | 14.5 9.4–22.4ROR 14.7 · χ² 238 / p 6e-54 | 13.9 EB05 9.0 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 10.2 | no trial data cached |
| Renal tubular necrosis | 10 | 13.9 7.5–25.8ROR 14.0 · χ² 107 / p 2e-25 | 12.1 EB05 6.0 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 9.3 | no trial data cached |
| Neutrophil count decreased | 41 | 13.8 10.2–18.7ROR 14.2 · χ² 476 / p 7e-106 | 13.6 EB05 10.3 · IC025 +3.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 10.7 · 98% clinician | no trial data cached |
| Drug intolerance | 96 | 13.6 11.2–16.6ROR 14.5 · χ² 1,117 / p 4e-245 | 13.5 EB05 11.4 · IC025 +3.3 3/3 methods agree | Reporting / coding artifact | serious PRR 14.5 · ♀ 98% (drug 63%) · 93% clinician | no trial data cached |
| Gastroenteritis | 14 | 13.1 7.8–22.1ROR 13.3 · χ² 145 / p 1e-33 | 11.9 EB05 6.8 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.4 | no trial data cached |
| Rash erythematous | 45 | 13.1 9.9–17.5ROR 13.5 · χ² 493 / p 1e-109 | 12.9 EB05 9.9 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 17.8 · ♀ 90% (drug 63%) | no trial data cached |
| Mouth ulceration | 20 | 13.0 8.4–20.1ROR 13.2 · χ² 210 / p 7e-48 | 12.2 EB05 7.9 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 11.5 | no trial data cached |
| Pericarditis | 15 | 12.3 7.4–20.4ROR 12.4 · χ² 145 / p 1e-33 | 11.1 EB05 6.5 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Angioedema (deep swelling of face/throat) | 39 | 12.1 8.9–16.5ROR 12.4 · χ² 386 / p 3e-86 | 11.7 EB05 8.7 · IC025 +2.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 8.5 · ♀ 89% (drug 63%) | no trial data cached |
| Stevens-johnson syndrome (severe blistering skin reaction) | 19 | 11.7 7.5–18.2ROR 11.8 · χ² 175 / p 3e-40 | 10.7 EB05 6.8 · IC025 +2.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 7.8 | no trial data cached |
| Disseminated intravascular coagulation | 12 | 11.6 6.6–20.4ROR 11.7 · χ² 106 / p 3e-25 | 9.9 EB05 5.5 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.1 | no trial data cached |
| Chronic kidney disease | 64 | 11.4 9.0–14.5ROR 11.9 · χ² 600 / p 9e-133 | 11.2 EB05 9.0 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.7 | no trial data cached |
| Hyperlipidaemia | 10 | 11.4 6.2–21.2ROR 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 8.4 | no trial data cached |
| Irritable bowel syndrome | 17 | 10.9 6.8–17.5ROR 11.0 · χ² 143 / p 3e-33 | 9.7 EB05 6.0 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.2 | no trial data cached |
| Hypokalaemia (low potassium) | 36 | 10.7 7.8–14.8ROR 11.0 · χ² 308 / p 2e-69 | 10.2 EB05 7.5 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 7.3 · 97% clinician | no trial data cached |
| Type 2 diabetes mellitus | 26 | 10.5 7.2–15.4ROR 10.7 · χ² 215 / p 6e-49 | 9.8 EB05 6.7 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 7.1 | no trial data cached |
| Viral infection | 25 | 10.3 7.0–15.2ROR 10.4 · χ² 201 / p 8e-46 | 9.5 EB05 6.5 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 9.6 · ♀ 83% (drug 63%) | no trial data cached |
| Septic shock | 32 | 10.1 7.2–14.3ROR 10.3 · χ² 255 / p 1e-57 | 9.5 EB05 6.9 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 6.7 · ♀ 85% (drug 63%) · 93% clinician | 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 hypersensitivity | 252 | 17.8 15.9–19.9ROR 21.1 · χ² 4,000 / p <1e-300 | 17.7 EB05 16.0 · IC025 +3.9 3/3 methods agree | Labeled (related wording) related wording | serious PRR 18.1 · ♀ 91% (drug 63%) | no trial data cached |
| Infection | 106 | 10.1 8.4–12.1ROR 10.7 · χ² 861 / p 2e-189 | 9.9 EB05 8.4 · IC025 +2.9 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 8.4 · ♀ 92% (drug 63%) · 90% clinician | no trial data cached |
| Drug intolerance | 96 | 13.6 11.2–16.6ROR 14.5 · χ² 1,117 / p 4e-245 | 13.5 EB05 11.4 · IC025 +3.3 3/3 methods agree | Reporting / coding artifact | serious PRR 14.5 · ♀ 98% (drug 63%) · 93% clinician | no trial data cached |
| Therapeutic product effect incomplete | 95 | 18.4 15.1–22.3ROR 19.5 · χ² 1,548 / p <1e-300 | 18.3 EB05 15.4 · IC025 +3.7 3/3 methods agree | Reporting / coding artifact | serious PRR 23.0 · ♀ 85% (drug 63%) · 95% clinician | no trial data cached |
| Urticaria (hives) | 71 | 5.8 4.6–7.3ROR 6.1 · χ² 282 / p 2e-63 | 5.6 EB05 4.6 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.8 | no trial data cached |
| Chronic kidney disease | 64 | 11.4 9.0–14.5ROR 11.9 · χ² 600 / p 9e-133 | 11.2 EB05 9.0 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.7 | no trial data cached |
| White blood cell count decreased | 56 | 7.1 5.5–9.1ROR 7.3 · χ² 286 / p 1e-64 | 6.7 EB05 5.4 · IC025 +2.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 6.4 · 91% clinician | no trial data cached |
| Staphylococcal infection | 50 | 20.7 15.7–27.2ROR 21.3 · χ² 917 / p 1e-201 | 20.5 EB05 16.1 · IC025 +3.6 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 15.2 · ♀ 97% (drug 63%) · 94% clinician | no trial data cached |
| Platelet count increased | 50 | 52.5 40.0–69.0ROR 54.2 · χ² 2,467 / p <1e-300 | 51.3 EB05 40.5 · IC025 +4.6 3/3 methods agree | Lab value / disease marker | serious PRR 45.9 · ♀ 94% (drug 63%) · 94% clinician | no trial data cached |
| Alanine aminotransferase increased | 45 | 10.0 7.5–13.4ROR 10.3 · χ² 357 / p 6e-80 | 9.6 EB05 7.3 · IC025 +2.7 3/3 methods agree | Labeled (related wording) related wording | serious PRR 7.5 · 98% clinician | no trial data cached |
| Rash erythematous | 45 | 13.1 9.9–17.5ROR 13.5 · χ² 493 / p 1e-109 | 12.9 EB05 9.9 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 17.8 · ♀ 90% (drug 63%) | no trial data cached |
| Red blood cell sedimentation rate increased | 43 | 53.2 39.6–71.5ROR 54.7 · χ² 2,143 / p <1e-300 | 51.8 EB05 40.1 · IC025 +4.5 3/3 methods agree | Lab value / disease marker | serious PRR 40.0 · ♀ 100% (drug 63%) · 98% clinician | no trial data cached |
| Neutrophil count decreased | 41 | 13.8 10.2–18.7ROR 14.2 · χ² 476 / p 7e-106 | 13.6 EB05 10.3 · IC025 +3.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 10.7 · 98% clinician | no trial data cached |
| Clostridium difficile infection | 41 | 25.9 19.1–35.1ROR 26.6 · χ² 956 / p 3e-210 | 25.6 EB05 19.7 · IC025 +3.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 18.1 · ♀ 100% (drug 63%) | no trial data cached |
| Secretion discharge | 41 | 45.5 33.6–61.6ROR 46.7 · χ² 1,736 / p <1e-300 | 44.5 EB05 34.2 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious PRR 49.6 · ♀ 100% (drug 63%) · 95% clinician | 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.
- Secretion discharge — n=41, PRR 45.5
- Eye inflammation — n=22, PRR 31.9
- Paralysis — n=24, PRR 22.9
- Drug eruption — n=26, PRR 20.2
- Muscle tightness — n=23, PRR 19.5
- Obesity — n=21, PRR 18.0
- Liver injury — n=28, PRR 15.8
- End stage renal disease — n=20, PRR 14.9
- Hypocalcaemia — n=20, PRR 14.5
- Rash erythematous — n=45, PRR 13.1
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 Cefaclor?
In FDA FAERS, the most frequently co-reported reaction terms for Cefaclor are drug hypersensitivity, infection, urticaria, chronic kidney disease, white blood cell count decreased, staphylococcal infection. 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 Cefaclor have an FDA boxed warning?
No. The FDA label retrieved for Cefaclor has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Cefaclor 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 0878bdc2-0410-4938-9890-96523aa81c2f, effective 20190731; matched on
openfda.generic_name.exact:"CEFACLOR") - 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, fieldpatient.drug.openfda.generic_name.exact, 113 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.