Drug · FAERS side-effect profile with label screen
Acetylcysteine side effects: what 9,365 FDA adverse event reports show
Drug class
Antidote, Antidote for Acetaminophen Overdose, Mucolytic
FDA label (Established Pharmacologic Class) · compare the class
Who reports
9,365 reports · 89% serious · 1,754 with death outcome · 51% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Acetylcysteine injection is indicated to prevent or lessen hepatic injury after ingestion of a potentially hepatotoxic quantity of acetaminophen in adults and pediatric patients who weigh 5 kg or greater with acute ingestion or from repeated supratherapeutic ingestion (RSI).
FDA label, Indications and Usage
What it is
Acetylcysteine injection is an intravenous antidote for the treatment of acetaminophen overdose. Acetylcysteine is the nonproprietary name for the N-acetyl derivative of the naturally occurring amino acid, L-cysteine (N-acetyl-L cysteine,).
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
Reporting / coding artifact 1Lab value / disease marker 3Not in label — unassessed 36
What the badges mean
- 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. 1,077 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 |
|---|---|---|---|---|---|---|
| Congenital hiatus hernia | 120 | 2,675.9 2,052.3–3,489.1ROR 2,710.6 · χ² 143,845 / p <1e-300 | 1,013.0 EB05 869.8 · IC025 +7.3 3/3 methods agree | Not in label — unassessed | serious n=120 · ♀ 0% (drug 51%) | no trial data cached |
| Sinobronchitis | 23 | 403.0 258.5–628.2ROR 404.0 · χ² 7,463 / p <1e-300 | 265.7 EB05 186.5 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=23 · ♀ 100% (drug 51%) · 100% clinician | no trial data cached |
| Malignant melanoma stage 0 | 23 | 325.5 210.2–504.0ROR 326.3 · χ² 6,204 / p <1e-300 | 229.8 EB05 161.3 · IC025 +4.6 3/3 methods agree | Not in label — unassessed | serious n=23 · ♀ 0% (drug 51%) | no trial data cached |
| Vasomotor rhinitis | 12 | 222.6 123.0–402.9ROR 222.9 · χ² 2,208 / p <1e-300 | 153.5 EB05 93.5 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Body tinea | 44 | 189.3 139.3–257.4ROR 190.2 · χ² 7,420 / p <1e-300 | 162.3 EB05 125.9 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=44 · ♀ 100% (drug 51%) · 95% clinician | no trial data cached |
| Malignant melanoma in situ | 85 | 161.9 130.0–201.6ROR 163.4 · χ² 12,515 / p <1e-300 | 146.0 EB05 121.8 · IC025 +6.0 3/3 methods agree | Not in label — unassessed | serious n=85 · ♀ 0% (drug 51%) | no trial data cached |
| Prothrombin time ratio decreased | 25 | 92.4 62.0–137.9ROR 92.7 · χ² 2,084 / p <1e-300 | 83.3 EB05 59.3 · IC025 +4.4 3/3 methods agree | Lab value / disease marker | serious n=25 · 100% clinician | no trial data cached |
| Breath sounds abnormal | 140 | 65.4 55.3–77.2ROR 66.3 · χ² 8,556 / p <1e-300 | 63.0 EB05 54.7 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=139 · ♀ 7% (drug 51%) | no trial data cached |
| Inhibitory drug interaction | 44 | 63.7 47.2–85.8ROR 63.9 · χ² 2,577 / p <1e-300 | 60.4 EB05 46.8 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=44 · ♀ 100% (drug 51%) · 93% clinician | no trial data cached |
| Bronchiectasis | 166 | 57.2 49.1–66.6ROR 58.2 · χ² 8,881 / p <1e-300 | 55.4 EB05 48.7 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious n=164 · ♀ 19% (drug 51%) | no trial data cached |
| Benign prostatic hyperplasia | 128 | 56.7 47.6–67.5ROR 57.5 · χ² 6,774 / p <1e-300 | 54.9 EB05 47.3 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=128 · ♀ 0% (drug 51%) | no trial data cached |
| Anion gap | 15 | 53.7 32.2–89.5ROR 53.8 · χ² 706 / p 6e-156 | 49.3 EB05 31.7 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=15 | no trial data cached |
| Allergic sinusitis | 20 | 53.3 34.2–83.0ROR 53.4 · χ² 951 / p 4e-209 | 49.7 EB05 34.0 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=20 | no trial data cached |
| Hemianopia | 23 | 52.7 34.9–79.7ROR 52.9 · χ² 1,090 / p 2e-239 | 49.5 EB05 34.8 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=23 · ♀ 0% (drug 51%) | no trial data cached |
| Empyema | 43 | 49.3 36.5–66.7ROR 49.5 · χ² 1,944 / p <1e-300 | 47.3 EB05 36.6 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=43 · ♀ 0% (drug 51%) | no trial data cached |
| Infection susceptibility increased | 44 | 46.0 34.1–61.9ROR 46.2 · χ² 1,853 / p <1e-300 | 44.3 EB05 34.3 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=44 · ♀ 100% (drug 51%) · 95% clinician | no trial data cached |
| Dermatillomania | 11 | 43.0 23.7–78.0ROR 43.0 · χ² 402 / p 9e-90 | 39.5 EB05 23.5 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| Venoocclusive disease | 47 | 42.8 32.1–57.0ROR 43.0 · χ² 1,839 / p <1e-300 | 41.3 EB05 32.3 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=47 · 100% clinician | no trial data cached |
| Respiratory tract haemorrhage | 11 | 41.9 23.1–76.1ROR 42.0 · χ² 392 / p 1e-87 | 38.6 EB05 23.0 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| Sputum purulent | 12 | 41.3 23.3–73.0ROR 41.3 · χ² 424 / p 2e-94 | 38.3 EB05 23.3 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Soft tissue swelling | 10 | 40.6 21.7–75.8ROR 40.6 · χ² 341 / p 2e-76 | 37.3 EB05 21.6 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Graft loss | 12 | 37.2 21.0–65.8ROR 37.3 · χ² 381 / p 4e-85 | 34.8 EB05 21.2 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Respiratory tract oedema | 11 | 34.0 18.7–61.6ROR 34.0 · χ² 315 / p 9e-71 | 31.8 EB05 18.9 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| Device related sepsis | 30 | 33.5 23.4–48.0ROR 33.6 · χ² 901 / p 4e-198 | 32.4 EB05 23.8 · IC025 +3.8 3/3 methods agree | Reporting / coding artifact | serious n=30 · ♀ 0% (drug 51%) | no trial data cached |
| Mucosal erosion | 13 | 32.5 18.8–56.2ROR 32.6 · χ² 361 / p 8e-81 | 30.8 EB05 19.1 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=13 | no trial data cached |
| Full blood count abnormal | 136 | 29.2 24.7–34.6ROR 29.7 · χ² 3,634 / p <1e-300 | 28.8 EB05 24.9 · IC025 +4.4 3/3 methods agree | Lab value / disease marker | serious PRR 24.5 · ♀ 17% (drug 51%) | no trial data cached |
| Haemoperitoneum | 10 | 28.9 15.5–53.8ROR 28.9 · χ² 239 / p 4e-54 | 27.1 EB05 15.5 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Klebsiella infection | 61 | 27.5 21.4–35.4ROR 27.7 · χ² 1,513 / p <1e-300 | 27.0 EB05 21.8 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=61 · ♀ 0% (drug 51%) · 90% clinician | no trial data cached |
| Anion gap increased | 15 | 25.3 15.2–42.1ROR 25.3 · χ² 322 / p 2e-72 | 24.3 EB05 15.5 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=15 | no trial data cached |
| Obstructive airways disorder | 124 | 25.1 21.1–30.0ROR 25.5 · χ² 2,819 / p <1e-300 | 24.8 EB05 21.3 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious PRR 16.7 · ♀ 19% (drug 51%) | no trial data cached |
| Sense of oppression | 13 | 25.0 14.5–43.2ROR 25.1 · χ² 273 / p 1e-61 | 23.9 EB05 14.7 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=13 | no trial data cached |
| Necrotising colitis | 14 | 24.7 14.6–41.8ROR 24.7 · χ² 292 / p 9e-66 | 23.7 EB05 14.8 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=14 | no trial data cached |
| Chronic fatigue syndrome | 15 | 24.4 14.7–40.6ROR 24.5 · χ² 310 / p 9e-70 | 23.5 EB05 15.0 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=15 | no trial data cached |
| Prothrombin time shortened | 15 | 24.2 14.5–40.2ROR 24.2 · χ² 307 / p 5e-69 | 23.2 EB05 14.8 · IC025 +2.9 3/3 methods agree | Lab value / disease marker | serious n=15 | no trial data cached |
| Toxic epidermal necrolysis (severe skin peeling reaction) | 159 | 23.8 20.4–27.8ROR 24.2 · χ² 3,422 / p <1e-300 | 23.5 EB05 20.6 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious PRR 15.2 · 96% clinician | no trial data cached |
| Hypercholesterolaemia | 100 | 23.6 19.4–28.7ROR 23.9 · χ² 2,123 / p <1e-300 | 23.3 EB05 19.7 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious PRR 15.9 · ♀ 0% (drug 51%) | no trial data cached |
| Anaphylactoid reaction | 42 | 23.2 17.1–31.4ROR 23.3 · χ² 860 / p 2e-189 | 22.7 EB05 17.5 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=37 · 100% clinician | no trial data cached |
| Abdominal abscess | 43 | 22.0 16.3–29.7ROR 22.1 · χ² 833 / p 2e-183 | 21.6 EB05 16.7 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=43 · ♀ 0% (drug 51%) | no trial data cached |
| Sputum increased | 20 | 21.4 13.8–33.1ROR 21.4 · χ² 364 / p 2e-81 | 20.7 EB05 14.1 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=19 | no trial data cached |
| Acute prerenal failure | 11 | 21.2 11.7–38.4ROR 21.2 · χ² 190 / p 1e-43 | 20.0 EB05 11.3 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=10 | 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 |
|---|---|---|---|---|---|---|
| Dyspnoea (shortness of breath) | 779 | 3.1 2.9–3.3ROR 3.3 · χ² 1,125 / p 7e-247 | 3.1 EB05 2.9 · IC025 +1.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.6 | no trial data cached |
| Drug ineffective (drug did not work) | 670 | 1.1 1.1–1.2ROR 1.1 · χ² 12 / p 3e-4 | 1.1 EB05 1.1 · IC025 +0.1 | Reporting / coding artifact | serious PRR 1.9 | no trial data cached |
| Off label use (used outside approved label) | 669 | 1.7 1.6–1.9ROR 1.8 · χ² 212 / p 2e-48 | 1.7 EB05 1.6 · IC025 +0.7 | Reporting / coding artifact | serious PRR 1.8 | no trial data cached |
| Pneumonia (lung infection) | 635 | 4.4 4.1–4.7ROR 4.7 · χ² 1,690 / p <1e-300 | 4.4 EB05 4.1 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 2.9 | no trial data cached |
| Pyrexia (fever) | 510 | 3.3 3.0–3.6ROR 3.4 · χ² 828 / p 2e-182 | 3.3 EB05 3.1 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 2.6 | no trial data cached |
| Fatigue (tiredness) | 455 | 1.3 1.2–1.4ROR 1.3 · χ² 35 / p 2e-9 | 1.3 EB05 1.2 · IC025 +0.2 | Not in label — unassessed | serious PRR 1.4 | no trial data cached |
| Nausea | 436 | 1.2 1.1–1.4ROR 1.2 · χ² 20 / p 3e-6 | 1.2 EB05 1.1 · IC025 +0.1 | Labeled adverse reaction exact term | serious PRR 1.3 | no trial data cached |
| Diarrhoea (diarrhea) | 348 | 1.2 1.1–1.3ROR 1.2 · χ² 13 / p 2e-4 | 1.2 EB05 1.1 · IC025 +0.1 | Not in label — unassessed | serious PRR 1.2 | no trial data cached |
| Vomiting | 334 | 1.6 1.4–1.8ROR 1.6 · χ² 75 / p 2e-18 | 1.6 EB05 1.5 · IC025 +0.5 | Labeled adverse reaction exact term | serious PRR 1.4 | no trial data cached |
| Death | 316 | 0.8 0.7–0.9ROR 0.8 · χ² 13 / p 2e-4 | 0.8 EB05 0.7 · IC025 -0.5 PRR-only: not supported by EBGM or IC | Outcome field, not a reaction | serious PRR 0.5 | no trial data cached |
| Hypertension (high blood pressure) | 316 | 3.3 3.0–3.7ROR 3.4 · χ² 520 / p 2e-115 | 3.3 EB05 3.0 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 2.6 | no trial data cached |
| Cough | 313 | 2.5 2.2–2.8ROR 2.6 · χ² 285 / p 3e-64 | 2.5 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.5 | no trial data cached |
| Chronic obstructive pulmonary disease | 311 | 13.4 12.0–15.0ROR 13.9 · χ² 3,551 / p <1e-300 | 13.3 EB05 12.1 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious PRR 9.9 | no trial data cached |
| Condition aggravated | 296 | 2.2 2.0–2.5ROR 2.2 · χ² 194 / p 2e-44 | 2.2 EB05 2.0 · IC025 +0.9 | Reporting / coding artifact | serious PRR 2.0 | no trial data cached |
| Hypotension (low blood pressure) | 293 | 3.3 2.9–3.7ROR 3.4 · χ² 465 / p 2e-103 | 3.3 EB05 3.0 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.4 | 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.
- Congenital hiatus hernia — n=120, PRR 2,675.9
- Sinobronchitis — n=23, PRR 403.0
- Malignant melanoma stage 0 — n=23, PRR 325.5
- Body tinea — n=44, PRR 189.3
- Malignant melanoma in situ — n=85, PRR 161.9
- Breath sounds abnormal — n=140, PRR 65.4
- Inhibitory drug interaction — n=44, PRR 63.7
- Bronchiectasis — n=166, PRR 57.2
- Benign prostatic hyperplasia — n=128, PRR 56.7
- Allergic sinusitis — n=20, PRR 53.3
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 Acetylcysteine?
In FDA FAERS, the most frequently co-reported reaction terms for Acetylcysteine are dyspnoea, pneumonia, pyrexia, fatigue, nausea, diarrhoea. 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 Acetylcysteine have an FDA boxed warning?
No. The FDA label retrieved for Acetylcysteine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Acetylcysteine 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 3b0310d2-4e70-4b94-8d69-cb5999a32b54, effective 20250912; matched on
openfda.generic_name.exact:"ACETYLCYSTEINE") - 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, 1,117 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.