Acetaminophen side effects: what 6,260 FDA adverse event reports show

Acetaminophen And Dextromethorphan Hydrobromide · 174 reaction terms · 8,103 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Who reports

6,260 reports · 22% serious · 107 with death outcome · 60% 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

Reporting / coding artifact 19Not in label — unassessed 21

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.
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. 134 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
Accidental overdose	368	34.0 30.8–37.6ROR 36.1 · χ² 11,667 / p <1e-300	33.6 EB05 30.9 · IC025 +4.8 3/3 methods agree	Reporting / coding artifact	serious PRR 20.2 · 97% consumer	no trial data cached
Product packaging issue	41	14.9 10.9–20.2ROR 14.9 · χ² 514 / p 5e-114	14.6 EB05 11.1 · IC025 +3.1 3/3 methods agree	Reporting / coding artifact	97% consumer	no trial data cached
Mydriasis	50	13.1 9.9–17.3ROR 13.2 · χ² 545 / p 8e-121	12.8 EB05 10.0 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 21.3 · 94% consumer	no trial data cached
Expired product administered	112	11.3 9.4–13.6ROR 11.5 · χ² 1,043 / p 4e-229	11.2 EB05 9.5 · IC025 +3.1 3/3 methods agree	Reporting / coding artifact	serious n=7 · 99% consumer	no trial data cached
Euphoric mood	34	11.1 7.9–15.5ROR 11.1 · χ² 301 / p 1e-67	10.5 EB05 7.7 · IC025 +2.7 3/3 methods agree	Not in label — unassessed	serious n=23 · 100% consumer	no trial data cached
Psychomotor hyperactivity	45	9.1 6.8–12.1ROR 9.1 · χ² 314 / p 2e-70	8.6 EB05 6.6 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 17.5 · 95% consumer	no trial data cached
Product taste abnormal	34	8.5 6.1–11.9ROR 8.5 · χ² 216 / p 3e-49	7.8 EB05 5.8 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious n=2 · 85% consumer	no trial data cached
Drug administration error	66	7.1 5.6–9.0ROR 7.2 · χ² 340 / p 3e-76	6.8 EB05 5.5 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 5.8 · 95% consumer	no trial data cached
Overdose	450	7.0 6.4–7.6ROR 7.4 · χ² 2,312 / p <1e-300	6.9 EB05 6.4 · IC025 +2.6 3/3 methods agree	Reporting / coding artifact	serious PRR 5.4 · 97% consumer	no trial data cached
Extra dose administered	72	6.0 4.8–7.6ROR 6.1 · χ² 298 / p 4e-67	5.8 EB05 4.8 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious n=2 · 97% consumer	no trial data cached
Incorrect drug administration duration	48	5.6 4.3–7.5ROR 5.7 · χ² 179 / p 5e-41	5.4 EB05 4.2 · IC025 +1.9 3/3 methods agree	Reporting / coding artifact	serious PRR 6.1 · 96% consumer	no trial data cached
Retching	34	5.4 3.8–7.5ROR 5.4 · χ² 116 / p 2e-27	5.0 EB05 3.7 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious PRR 3.3 · 97% consumer	no trial data cached
No adverse event	245	4.6 4.1–5.2ROR 4.8 · χ² 698 / p 4e-154	4.6 EB05 4.1 · IC025 +2.0 3/3 methods agree	Reporting / coding artifact	serious PRR 7.3 · 96% consumer	no trial data cached
Incorrect product administration duration	28	4.6 3.2–6.7ROR 4.6 · χ² 76 / p 2e-18	4.3 EB05 3.1 · IC025 +1.5 3/3 methods agree	Reporting / coding artifact	serious n=4 · 96% consumer	no trial data cached
Inappropriate schedule of drug administration	98	4.6 3.7–5.5ROR 4.6 · χ² 268 / p 1e-60	4.5 EB05 3.8 · IC025 +1.8 3/3 methods agree	Reporting / coding artifact	serious PRR 5.1 · 92% consumer	no trial data cached
Hallucination (hallucinations)	90	4.0 3.3–4.9ROR 4.1 · χ² 202 / p 4e-46	3.9 EB05 3.3 · IC025 +1.6 3/3 methods agree	Not in label — unassessed	serious PRR 11.8 · 91% consumer	no trial data cached
Abnormal behaviour	44	3.7 2.8–5.0ROR 3.7 · χ² 84 / p 3e-20	3.6 EB05 2.8 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 8.5 · 85% consumer	no trial data cached
Seasonal allergy	15	3.6 2.1–5.9ROR 3.6 · χ² 25 / p 3e-7	3.3 EB05 2.1 · IC025 +0.8 3/3 methods agree	Not in label — unassessed	serious n=5	no trial data cached
Gastroenteritis viral	19	3.5 2.2–5.5ROR 3.5 · χ² 32 / p 9e-9	3.3 EB05 2.2 · IC025 +1.0 3/3 methods agree	Not in label — unassessed	serious PRR 8.3	no trial data cached
Hallucination, visual	22	3.5 2.3–5.3ROR 3.5 · χ² 37 / p 6e-10	3.3 EB05 2.3 · IC025 +1.0 3/3 methods agree	Not in label — unassessed	serious PRR 9.1 · 90% consumer	no trial data cached
Paraesthesia oral	15	3.5 2.1–5.8ROR 3.5 · χ² 24 / p 4e-7	3.2 EB05 2.1 · IC025 +0.8 3/3 methods agree	Not in label — unassessed	serious PRR 12.0	no trial data cached
Feeling jittery	19	3.3 2.1–5.2ROR 3.3 · χ² 29 / p 4e-8	3.1 EB05 2.1 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious n=8	no trial data cached
Drug abuse	83	3.3 2.7–4.1ROR 3.4 · χ² 133 / p 5e-31	3.3 EB05 2.7 · IC025 +1.3 3/3 methods agree	Reporting / coding artifact	serious PRR 8.5 · ♀ 37% (drug 60%) · 92% consumer	no trial data cached
Drug ineffective (drug did not work)	1,306	3.3 3.2–3.5ROR 3.9 · χ² 2,257 / p <1e-300	3.3 EB05 3.2 · IC025 +1.6 3/3 methods agree	Reporting / coding artifact	serious PRR 1.2 · 95% consumer	no trial data cached
Therapeutic response unexpected	44	3.3 2.4–4.4ROR 3.3 · χ² 67 / p 1e-16	3.2 EB05 2.5 · IC025 +1.2 3/3 methods agree	Reporting / coding artifact	serious PRR 3.1 · 93% consumer	no trial data cached
Product complaint	24	3.2 2.2–4.8ROR 3.2 · χ² 35 / p 2e-9	3.1 EB05 2.2 · IC025 +0.9 3/3 methods agree	Reporting / coding artifact	serious n=3 · 100% consumer	no trial data cached
Acute hepatic failure	13	3.2 1.9–5.5ROR 3.2 · χ² 18 / p 1e-5	2.9 EB05 1.9 · IC025 +0.6	Not in label — unassessed	serious PRR 8.4	no trial data cached
Product physical issue	19	3.2 2.0–5.0ROR 3.2 · χ² 26 / p 1e-7	3.0 EB05 2.0 · IC025 +0.8 3/3 methods agree	Reporting / coding artifact	–	no trial data cached
Ear infection	25	3.2 2.1–4.7ROR 3.2 · χ² 35 / p 2e-9	3.0 EB05 2.2 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 5.4	no trial data cached
Somnolence (drowsiness)	178	3.0 2.6–3.4ROR 3.0 · χ² 232 / p 1e-52	2.9 EB05 2.6 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.0 · 89% consumer	no trial data cached
Disorientation	35	3.0 2.1–4.1ROR 3.0 · χ² 43 / p 2e-11	2.9 EB05 2.2 · IC025 +1.0 3/3 methods agree	Not in label — unassessed	serious PRR 6.2 · 97% consumer	no trial data cached
Cough	245	2.9 2.6–3.3ROR 3.0 · χ² 314 / p 1e-70	2.9 EB05 2.6 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.1 · 80% consumer	no trial data cached
Drug prescribing error	17	2.9 1.8–4.7ROR 2.9 · χ² 20 / p 5e-6	2.8 EB05 1.8 · IC025 +0.7	Reporting / coding artifact	–	no trial data cached
Accidental exposure to product	84	2.8 2.3–3.5ROR 2.8 · χ² 97 / p 4e-23	2.8 EB05 2.3 · IC025 +1.1 3/3 methods agree	Reporting / coding artifact	serious PRR 6.9 · 96% consumer	no trial data cached
Hypoaesthesia oral	12	2.7 1.5–4.7ROR 2.7 · χ² 11 / p 5e-4	2.5 EB05 1.5 · IC025 +0.3	Not in label — unassessed	serious PRR 5.4	no trial data cached
Wrong technique in product usage process	159	2.6 2.3–3.1ROR 2.7 · χ² 161 / p 3e-37	2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree	Reporting / coding artifact	serious PRR 2.1 · 95% consumer	no trial data cached
Drug effective for unapproved indication	23	2.6 1.8–4.0ROR 2.6 · χ² 22 / p 2e-6	2.5 EB05 1.8 · IC025 +0.6	Not in label — unassessed	100% consumer	no trial data cached
Product use issue	146	2.6 2.2–3.1ROR 2.7 · χ² 145 / p 1e-33	2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree	Reporting / coding artifact	serious PRR 0.9 · 95% consumer	no trial data cached
Brain fog	11	2.5 1.4–4.6ROR 2.5 · χ² 9 / p 0.002	2.4 EB05 1.4 · IC025 +0.2	Not in label — unassessed	serious PRR 9.3	no trial data cached
Sinus congestion	10	2.5 1.3–4.6ROR 2.5 · χ² 7 / p 0.003	2.3 EB05 1.4 · IC025 +0.1	Not in label — unassessed	serious n=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)	1,306	3.3 3.2–3.5ROR 3.9 · χ² 2,257 / p <1e-300	3.3 EB05 3.2 · IC025 +1.6 3/3 methods agree	Reporting / coding artifact	serious PRR 1.2 · 95% consumer	no trial data cached
Overdose	450	7.0 6.4–7.6ROR 7.4 · χ² 2,312 / p <1e-300	6.9 EB05 6.4 · IC025 +2.6 3/3 methods agree	Reporting / coding artifact	serious PRR 5.4 · 97% consumer	no trial data cached
Accidental overdose	368	34.0 30.8–37.6ROR 36.1 · χ² 11,667 / p <1e-300	33.6 EB05 30.9 · IC025 +4.8 3/3 methods agree	Reporting / coding artifact	serious PRR 20.2 · 97% consumer	no trial data cached
Dizziness	366	2.5 2.2–2.7ROR 2.6 · χ² 324 / p 1e-72	2.5 EB05 2.3 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 3.4 · 93% consumer	no trial data cached
Diarrhoea (diarrhea)	355	1.8 1.7–2.0ROR 1.9 · χ² 142 / p 6e-33	1.8 EB05 1.7 · IC025 +0.7	Not in label — unassessed	serious PRR 1.9 · 85% consumer	no trial data cached
Vomiting	280	2.0 1.8–2.2ROR 2.0 · χ² 142 / p 5e-33	2.0 EB05 1.8 · IC025 +0.8	Not in label — unassessed	serious PRR 2.7 · 87% consumer	no trial data cached
Cough	245	2.9 2.6–3.3ROR 3.0 · χ² 314 / p 1e-70	2.9 EB05 2.6 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.1 · 80% consumer	no trial data cached
No adverse event	245	4.6 4.1–5.2ROR 4.8 · χ² 698 / p 4e-154	4.6 EB05 4.1 · IC025 +2.0 3/3 methods agree	Reporting / coding artifact	serious PRR 7.3 · 96% consumer	no trial data cached
Somnolence (drowsiness)	178	3.0 2.6–3.4ROR 3.0 · χ² 232 / p 1e-52	2.9 EB05 2.6 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 4.0 · 89% consumer	no trial data cached
Feeling abnormal	165	2.3 2.0–2.7ROR 2.3 · χ² 121 / p 2e-28	2.3 EB05 2.0 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 6.0 · 92% consumer	no trial data cached
Insomnia (trouble sleeping)	164	2.1 1.8–2.4ROR 2.1 · χ² 89 / p 2e-21	2.1 EB05 1.8 · IC025 +0.8	Not in label — unassessed	serious PRR 3.5 · 86% consumer	no trial data cached
Wrong technique in product usage process	159	2.6 2.3–3.1ROR 2.7 · χ² 161 / p 3e-37	2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree	Reporting / coding artifact	serious PRR 2.1 · 95% consumer	no trial data cached
Incorrect dose administered	158	2.4 2.0–2.7ROR 2.4 · χ² 123 / p 8e-29	2.3 EB05 2.1 · IC025 +1.0 3/3 methods agree	Reporting / coding artifact	serious PRR 3.2 · 88% consumer	no trial data cached
Product use issue	146	2.6 2.2–3.1ROR 2.7 · χ² 145 / p 1e-33	2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree	Reporting / coding artifact	serious PRR 0.9 · 95% consumer	no trial data cached
Product use in unapproved indication	120	1.6 1.4–2.0ROR 1.7 · χ² 30 / p 2e-8	1.6 EB05 1.4 · IC025 +0.4	Reporting / coding artifact	serious PRR 1.0 · 94% consumer	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.

Mydriasis — n=50, PRR 13.1
Euphoric mood — n=34, PRR 11.1
Psychomotor hyperactivity — n=45, PRR 9.1
Extra dose administered — n=72, PRR 6.0
Retching — n=34, PRR 5.4
Hallucination — n=90, PRR 4.0
Abnormal behaviour — n=44, PRR 3.7
Hallucination, visual — n=22, PRR 3.5
Ear infection — n=25, PRR 3.2
Somnolence — n=178, PRR 3.0

✓ 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 dizziness, diarrhoea, vomiting, cough, somnolence, feeling abnormal. 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, field patient.drug.openfda.generic_name.exact, 174 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.