Drug · FAERS side-effect profile with label screen
Acetaminophen side effects: what 7,143 FDA adverse event reports show
Drug class
Not stated in label
Who reports
7,143 reports · 29% serious · 106 with death outcome · 79% female
openFDA FAERS counts, all years, deduplication not applied
Used for
temporarily relieves minor aches and pains due to: headache muscular aches backache minor pain of arthritis the common cold toothache premenstrual and menstrual cramps temporarily reduces fever
FDA label, Indications and Usage
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
Likely indication confounding 2Reporting / coding artifact 12Not in label — unassessed 26
What the badges mean
- 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. 323 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 |
|---|---|---|---|---|---|---|
| Drug effective for unapproved indication | 133 | 13.4 11.3–15.9ROR 13.7 · χ² 1,511 / p <1e-300 | 13.3 EB05 11.5 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=2 · 100% consumer | no trial data cached |
| Ulcer | 52 | 9.6 7.3–12.6ROR 9.7 · χ² 391 / p 2e-87 | 9.2 EB05 7.2 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 · 90% consumer | no trial data cached |
| Migraine | 264 | 8.2 7.3–9.2ROR 8.5 · χ² 1,661 / p <1e-300 | 8.1 EB05 7.3 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 11.4 · 84% consumer | no trial data cached |
| Gastric disorder | 77 | 6.5 5.2–8.1ROR 6.6 · χ² 353 / p 5e-79 | 6.3 EB05 5.2 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 4.6 · 88% consumer | no trial data cached |
| Gastric ulcer | 42 | 6.5 4.8–8.8ROR 6.5 · χ² 189 / p 2e-43 | 6.1 EB05 4.7 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 13.5 · 81% consumer | no trial data cached |
| Gastric haemorrhage | 25 | 6.3 4.3–9.4ROR 6.4 · χ² 107 / p 2e-25 | 5.7 EB05 4.1 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 13.0 · 96% consumer | no trial data cached |
| Feeling jittery | 41 | 6.3 4.7–8.6ROR 6.3 · χ² 178 / p 7e-41 | 5.9 EB05 4.5 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious n=2 · 92% consumer | no trial data cached |
| Therapeutic response unexpected | 89 | 5.8 4.7–7.1ROR 5.9 · χ² 350 / p 2e-78 | 5.6 EB05 4.7 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 5.6 · 97% consumer | no trial data cached |
| End stage renal disease | 31 | 4.9 3.5–7.0ROR 5.0 · χ² 94 / p 2e-22 | 4.6 EB05 3.4 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 9.8 | no trial data cached |
| Contraindicated product administered | 47 | 4.6 3.4–6.1ROR 4.6 · χ² 128 / p 6e-30 | 4.4 EB05 3.4 · IC025 +1.7 3/3 methods agree | Reporting / coding artifact | serious PRR 2.6 · 98% consumer | no trial data cached |
| Drug ineffective (drug did not work) | 2,009 | 4.5 4.3–4.7ROR 5.8 · χ² 5,790 / p <1e-300 | 4.5 EB05 4.3 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 1.7 · 96% consumer | no trial data cached |
| Drug effect incomplete | 55 | 4.4 3.4–5.7ROR 4.4 · χ² 140 / p 1e-32 | 4.2 EB05 3.4 · IC025 +1.6 3/3 methods agree | Reporting / coding artifact | serious PRR 3.1 · 87% consumer | no trial data cached |
| Chronic kidney disease | 111 | 4.3 3.5–5.1ROR 4.3 · χ² 274 / p 9e-62 | 4.2 EB05 3.6 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 | no trial data cached |
| Drug administration error | 45 | 4.2 3.2–5.7ROR 4.3 · χ² 109 / p 1e-25 | 4.1 EB05 3.2 · IC025 +1.5 3/3 methods agree | Reporting / coding artifact | serious PRR 3.3 · 98% consumer | no trial data cached |
| Vitamin d deficiency | 14 | 4.2 2.5–7.1ROR 4.2 · χ² 31 / p 1e-8 | 3.8 EB05 2.4 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 9.3 | no trial data cached |
| Drug ineffective for unapproved indication | 80 | 4.2 3.4–5.2ROR 4.3 · χ² 193 / p 3e-44 | 4.1 EB05 3.4 · IC025 +1.7 3/3 methods agree | Reporting / coding artifact | serious PRR 2.1 · 91% consumer | no trial data cached |
| Product physical issue | 28 | 4.1 2.9–6.0ROR 4.1 · χ² 63 / p 9e-16 | 3.9 EB05 2.8 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious n=7 · 85% consumer | no trial data cached |
| Drug effect less than expected | 18 | 3.8 2.4–6.0ROR 3.8 · χ² 34 / p 3e-9 | 3.5 EB05 2.3 · IC025 +1.0 3/3 methods agree | Reporting / coding artifact | serious n=2 | no trial data cached |
| Poor quality sleep | 27 | 3.7 2.5–5.4ROR 3.7 · χ² 51 / p 5e-13 | 3.5 EB05 2.5 · IC025 +1.2 3/3 methods agree | Reporting / coding artifact | serious PRR 1.5 · 100% consumer | no trial data cached |
| Tooth fracture | 13 | 3.5 2.0–6.0ROR 3.5 · χ² 20 / p 3e-6 | 3.1 EB05 2.0 · IC025 +0.7 | Not in label — unassessed | serious PRR 8.0 | no trial data cached |
| Product quality issue | 148 | 3.2 2.7–3.8ROR 3.3 · χ² 226 / p 2e-51 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Reporting / coding artifact | serious PRR 2.5 · 97% consumer | no trial data cached |
| Dental caries | 12 | 3.2 1.8–5.6ROR 3.2 · χ² 16 / p 3e-5 | 2.9 EB05 1.8 · IC025 +0.6 | Not in label — unassessed | serious PRR 8.9 | no trial data cached |
| Initial insomnia | 11 | 3.2 1.8–5.7ROR 3.2 · χ² 14 / p 8e-5 | 2.9 EB05 1.7 · IC025 +0.5 | Not in label — unassessed | serious n=3 | no trial data cached |
| Product use in unapproved indication | 262 | 3.2 2.8–3.5ROR 3.2 · χ² 386 / p 2e-86 | 3.1 EB05 2.8 · IC025 +1.4 3/3 methods agree | Reporting / coding artifact | serious PRR 0.9 · 93% consumer | no trial data cached |
| Tubulointerstitial nephritis | 20 | 3.1 2.0–4.9ROR 3.1 · χ² 27 / p 1e-7 | 3.0 EB05 2.0 · IC025 +0.8 3/3 methods agree | Not in label — unassessed | serious PRR 6.2 | no trial data cached |
| Impaired driving ability | 12 | 3.1 1.8–5.5ROR 3.1 · χ² 15 / p 5e-5 | 2.8 EB05 1.8 · IC025 +0.5 | Not in label — unassessed | serious PRR 4.1 | no trial data cached |
| Incorrect drug administration duration | 30 | 3.1 2.2–4.4ROR 3.1 · χ² 40 / p 1e-10 | 3.0 EB05 2.2 · IC025 +1.0 3/3 methods agree | Reporting / coding artifact | serious PRR 9.8 · 100% consumer | no trial data cached |
| Abdominal discomfort | 170 | 3.0 2.6–3.5ROR 3.0 · χ² 224 / p 5e-51 | 3.0 EB05 2.6 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 3.4 · 92% consumer | no trial data cached |
| Sinus disorder | 20 | 3.0 1.9–4.6ROR 3.0 · χ² 24 / p 5e-7 | 2.8 EB05 1.9 · IC025 +0.7 | Not in label — unassessed | serious PRR 9.5 | no trial data cached |
| Bladder disorder | 10 | 3.0 1.6–5.5ROR 3.0 · χ² 11 / p 5e-4 | 2.7 EB05 1.6 · IC025 +0.4 | Not in label — unassessed | serious n=8 | no trial data cached |
| Seasonal allergy | 14 | 2.9 1.7–4.9ROR 2.9 · χ² 16 / p 4e-5 | 2.7 EB05 1.7 · IC025 +0.5 | Not in label — unassessed | serious n=8 | no trial data cached |
| Micturition urgency | 11 | 2.8 1.6–5.1ROR 2.9 · χ² 11 / p 4e-4 | 2.6 EB05 1.6 · IC025 +0.4 | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Dysmenorrhoea | 12 | 2.7 1.5–4.7ROR 2.7 · χ² 11 / p 4e-4 | 2.5 EB05 1.6 · IC025 +0.4 | Not in label — unassessed | serious n=3 | no trial data cached |
| Gastrointestinal pain | 10 | 2.7 1.4–5.0ROR 2.7 · χ² 9 / p 0.001 | 2.5 EB05 1.5 · IC025 +0.2 | Not in label — unassessed | – | no trial data cached |
| Abdominal pain upper | 183 | 2.6 2.3–3.0ROR 2.7 · χ² 183 / p 6e-42 | 2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.5 · 85% consumer | no trial data cached |
| Headache | 543 | 2.5 2.3–2.8ROR 2.7 · χ² 524 / p 3e-116 | 2.5 EB05 2.4 · IC025 +1.2 3/3 methods agree | Likely indication confounding term in indications | serious PRR 3.8 · 76% consumer | no trial data cached |
| Hypoaesthesia oral | 13 | 2.5 1.5–4.4ROR 2.5 · χ² 11 / p 6e-4 | 2.4 EB05 1.5 · IC025 +0.3 | Not in label — unassessed | serious PRR 4.9 | no trial data cached |
| Paraesthesia oral | 12 | 2.5 1.4–4.3ROR 2.5 · χ² 9 / p 0.001 | 2.3 EB05 1.4 · IC025 +0.2 | Not in label — unassessed | serious PRR 2.9 | no trial data cached |
| Pain in jaw | 23 | 2.4 1.6–3.6ROR 2.4 · χ² 17 / p 2e-5 | 2.3 EB05 1.6 · IC025 +0.5 | Likely indication confounding term in indications; also in warnings | serious PRR 5.0 | no trial data cached |
| Muscle tightness | 13 | 2.4 1.4–4.1ROR 2.4 · χ² 9 / p 0.001 | 2.2 EB05 1.4 · IC025 +0.2 | Not in label — unassessed | serious PRR 5.5 | 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 ineffective (drug did not work) | 2,009 | 4.5 4.3–4.7ROR 5.8 · χ² 5,790 / p <1e-300 | 4.5 EB05 4.3 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 1.7 · 96% consumer | no trial data cached |
| Headache | 543 | 2.5 2.3–2.8ROR 2.7 · χ² 524 / p 3e-116 | 2.5 EB05 2.4 · IC025 +1.2 3/3 methods agree | Likely indication confounding term in indications | serious PRR 3.8 · 76% consumer | no trial data cached |
| Nausea | 400 | 1.5 1.4–1.6ROR 1.5 · χ² 66 / p 2e-16 | 1.5 EB05 1.4 · IC025 +0.4 | Not in label — unassessed | serious PRR 2.3 | no trial data cached |
| Migraine | 264 | 8.2 7.3–9.2ROR 8.5 · χ² 1,661 / p <1e-300 | 8.1 EB05 7.3 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 11.4 · 84% consumer | no trial data cached |
| Product use in unapproved indication | 262 | 3.2 2.8–3.5ROR 3.2 · χ² 386 / p 2e-86 | 3.1 EB05 2.8 · IC025 +1.4 3/3 methods agree | Reporting / coding artifact | serious PRR 0.9 · 93% consumer | no trial data cached |
| Insomnia (trouble sleeping) | 204 | 2.2 2.0–2.6ROR 2.3 · χ² 141 / p 7e-33 | 2.2 EB05 2.0 · IC025 +0.9 | Not in label — unassessed | serious PRR 2.8 · 85% consumer | no trial data cached |
| Abdominal pain upper | 183 | 2.6 2.3–3.0ROR 2.7 · χ² 183 / p 6e-42 | 2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.5 · 85% consumer | no trial data cached |
| Abdominal discomfort | 170 | 3.0 2.6–3.5ROR 3.0 · χ² 224 / p 5e-51 | 3.0 EB05 2.6 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 3.4 · 92% consumer | no trial data cached |
| Anxiety | 156 | 1.6 1.4–1.9ROR 1.6 · χ² 35 / p 1e-9 | 1.6 EB05 1.4 · IC025 +0.4 | Not in label — unassessed | serious PRR 2.6 · 83% consumer | no trial data cached |
| Product quality issue | 148 | 3.2 2.7–3.8ROR 3.3 · χ² 226 / p 2e-51 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Reporting / coding artifact | serious PRR 2.5 · 97% consumer | no trial data cached |
| Feeling abnormal | 139 | 1.7 1.4–2.0ROR 1.7 · χ² 39 / p 2e-10 | 1.7 EB05 1.5 · IC025 +0.5 | Not in label — unassessed | serious PRR 3.6 · 87% consumer | no trial data cached |
| Drug effective for unapproved indication | 133 | 13.4 11.3–15.9ROR 13.7 · χ² 1,511 / p <1e-300 | 13.3 EB05 11.5 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=2 · 100% consumer | no trial data cached |
| Drug dependence | 122 | 2.2 1.8–2.6ROR 2.2 · χ² 79 / p 3e-19 | 2.2 EB05 1.9 · IC025 +0.8 | Reporting / coding artifact | serious PRR 4.4 · 99% consumer | no trial data cached |
| Back pain | 116 | 1.5 1.2–1.8ROR 1.5 · χ² 17 / p 2e-5 | 1.5 EB05 1.3 · IC025 +0.2 | Likely indication confounding term in indications | serious PRR 3.0 | no trial data cached |
| Chronic kidney disease | 111 | 4.3 3.5–5.1ROR 4.3 · χ² 274 / p 9e-62 | 4.2 EB05 3.6 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 | 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.
- Drug effective for unapproved indication — n=133, PRR 13.4
- Ulcer — n=52, PRR 9.6
- Migraine — n=264, PRR 8.2
- Gastric disorder — n=77, PRR 6.5
- Gastric ulcer — n=42, PRR 6.5
- Gastric haemorrhage — n=25, PRR 6.3
- Feeling jittery — n=41, PRR 6.3
- End stage renal disease — n=31, PRR 4.9
- Chronic kidney disease — n=111, PRR 4.3
- Tubulointerstitial nephritis — n=20, PRR 3.1
✓ A hand-written Bradford Hill causality assessment exists for this drug: Acetaminophen (paracetamol) ↔ Liver injury / hepatotoxicity.
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 Acetaminophen?
In FDA FAERS, the most frequently co-reported reaction terms for Acetaminophen are headache, nausea, migraine, insomnia, abdominal pain upper, abdominal discomfort. 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 Acetaminophen have an FDA boxed warning?
No. The FDA label retrieved for Acetaminophen has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Acetaminophen 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 004c39cd-b4f4-1cae-e063-6394a90a0697, effective 20251003; matched on
openfda.generic_name.exact:"ACETAMINOPHEN") - 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, 363 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.