Drug · FAERS side-effect profile with label screen

Acetaminophen and Chlorpheniramine side effects: what 1,013 FDA adverse event reports show

Acetaminophen And Chlorpheniramine Maleate · 13 reaction terms · 424 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Label matched

Acetaminophen (Acetaminophen)

closest FDA label found for this product string; brand list suppressed because the label is a related product, not an exact match

Who reports

1,013 reports · 18% serious · 10 with death outcome · 67% 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 10 strongest signals

Reporting / coding artifact 6Not in label — unassessed 4

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. 3 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
Drug effect decreased	161	61.2 53.1–70.5ROR 72.5 · χ² 9,464 / p <1e-300	60.6 EB05 53.1 · IC025 +5.4 3/3 methods agree	Reporting / coding artifact	100% consumer	no trial data cached
Drug ineffective for unapproved indication	41	15.2 11.3–20.6ROR 15.8 · χ² 532 / p 5e-118	15.0 EB05 11.4 · IC025 +3.2 3/3 methods agree	Reporting / coding artifact	98% consumer	no trial data cached
Somnolence (drowsiness)	131	13.5 11.5–15.8ROR 15.4 · χ² 1,517 / p <1e-300	13.4 EB05 11.6 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 3.4 · 98% consumer	no trial data cached
Choking	12	12.8 7.3–22.5ROR 12.9 · χ² 119 / p 5e-28	11.2 EB05 6.1 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 48.2	no trial data cached
Therapeutic response unexpected	22	10.1 6.7–15.3ROR 10.3 · χ² 172 / p 1e-39	9.2 EB05 6.1 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 11.5 · 100% consumer	no trial data cached
Respiratory tract congestion	6	7.8 3.5–17.3ROR 7.9 · χ² 29 / p 3e-8	5.3 EB05 2.6 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 28.9	no trial data cached
Psychomotor hyperactivity	6	7.5 3.4–16.6ROR 7.5 · χ² 27 / p 8e-8	5.1 EB05 2.5 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 13.2	no trial data cached
Product use complaint	5	6.7 2.8–16.0ROR 6.7 · χ² 19 / p 7e-6	4.5 EB05 2.1 · IC025 +0.6 3/3 methods agree	Reporting / coding artifact	serious n=5	no trial data cached
Expired product administered	8	5.0 2.5–10.0ROR 5.0 · χ² 22 / p 2e-6	4.0 EB05 2.2 · IC025 +0.8 3/3 methods agree	Reporting / coding artifact	serious n=4	no trial data cached
Drug abuse	18	4.5 2.8–7.0ROR 4.5 · χ² 45 / p 1e-11	4.0 EB05 2.7 · IC025 +1.2 3/3 methods agree	Reporting / coding artifact	serious PRR 12.0	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 effect decreased	161	61.2 53.1–70.5ROR 72.5 · χ² 9,464 / p <1e-300	60.6 EB05 53.1 · IC025 +5.4 3/3 methods agree	Reporting / coding artifact	100% consumer	no trial data cached
Somnolence (drowsiness)	131	13.5 11.5–15.8ROR 15.4 · χ² 1,517 / p <1e-300	13.4 EB05 11.6 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 3.4 · 98% consumer	no trial data cached
Drug ineffective for unapproved indication	41	15.2 11.3–20.6ROR 15.8 · χ² 532 / p 5e-118	15.0 EB05 11.4 · IC025 +3.2 3/3 methods agree	Reporting / coding artifact	98% consumer	no trial data cached
Therapeutic response unexpected	22	10.1 6.7–15.3ROR 10.3 · χ² 172 / p 1e-39	9.2 EB05 6.1 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 11.5 · 100% consumer	no trial data cached
Drug abuse	18	4.5 2.8–7.0ROR 4.5 · χ² 45 / p 1e-11	4.0 EB05 2.7 · IC025 +1.2 3/3 methods agree	Reporting / coding artifact	serious PRR 12.0	no trial data cached
Choking	12	12.8 7.3–22.5ROR 12.9 · χ² 119 / p 5e-28	11.2 EB05 6.1 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 48.2	no trial data cached
Expired product administered	8	5.0 2.5–10.0ROR 5.0 · χ² 22 / p 2e-6	4.0 EB05 2.2 · IC025 +0.8 3/3 methods agree	Reporting / coding artifact	serious n=4	no trial data cached
Intentional overdose	7	2.3 1.1–4.8ROR 2.3 · χ² 4 / p 0.025	2.1 EB05 1.1 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Reporting / coding artifact	–	no trial data cached
Psychomotor hyperactivity	6	7.5 3.4–16.6ROR 7.5 · χ² 27 / p 8e-8	5.1 EB05 2.5 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 13.2	no trial data cached
Respiratory tract congestion	6	7.8 3.5–17.3ROR 7.9 · χ² 29 / p 3e-8	5.3 EB05 2.6 · IC025 +0.9 3/3 methods agree	Not in label — unassessed	serious PRR 28.9	no trial data cached
Product use complaint	5	6.7 2.8–16.0ROR 6.7 · χ² 19 / p 7e-6	4.5 EB05 2.1 · IC025 +0.6 3/3 methods agree	Reporting / coding artifact	serious n=5	no trial data cached
Ocular discomfort	4	7.6 2.9–20.3ROR 7.7 · χ² 17 / p 2e-5	4.6 EB05 1.9 · IC025 +0.4	Not in label — unassessed	serious n=2	no trial data cached
Product packaging issue	3	6.7 2.2–20.7ROR 6.7 · χ² 9 / p 0.001	3.8 EB05 1.5 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Reporting / coding artifact	–	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.

Somnolence — n=131, PRR 13.5

✓ 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 and Chlorpheniramine?

In FDA FAERS, the most frequently co-reported reaction terms for Acetaminophen and Chlorpheniramine are somnolence, choking, psychomotor hyperactivity, respiratory tract congestion, ocular 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 and Chlorpheniramine have an FDA boxed warning?

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

Do FAERS signals prove that Acetaminophen and Chlorpheniramine 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, 13 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.