Drug · FAERS side-effect profile with label screen

Orphenadrine side effects: what 621 FDA adverse event reports show

Orphenadrine Citrate · 20 reaction terms · 240 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Label matched

Orphenadrine Citrate (Orphenadrine Citrate)

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

Who reports

621 reports · 68% serious · 65 with death outcome · 75% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Orphenadrine citrate extended-release tablets are indicated as an adjunct to rest, physical therapy and other measures for the relief of discomfort associated with acute painful musculo skeletal conditions.

FDA label, Indications and Usage

What it is

DESCRIPTION Orphenadrine citrate, USP is the citrate salt of orphenadrine (2-dimethyl-aminoethyl 2-methylbenzhydryl ether citrate). It occurs as a white, crystalline powder having a bitter taste. It is practically odorless; sparingly soluble in water, slightly soluble in alcohol and has a molecular weight of 461.51.

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 12 strongest signals

Reporting / coding artifact 2Lab value / disease marker 1Not in label — unassessed 9

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. 8 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
Tenderness	18	58.3 37.0–92.0ROR 60.0 · χ² 956 / p 3e-210	55.0 EB05 36.8 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious n=17	no trial data cached
Synovitis	21	39.3 25.8–59.9ROR 40.7 · χ² 746 / p 1e-164	38.0 EB05 26.3 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 34.9 · 100% clinician	no trial data cached
Oral pain	23	34.6 23.2–51.7ROR 35.9 · χ² 717 / p 3e-158	33.7 EB05 23.6 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 53.7 · 100% clinician	no trial data cached
Fibromyalgia	23	32.0 21.4–47.8ROR 33.2 · χ² 660 / p 6e-146	31.2 EB05 21.9 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 32.5 · 90% clinician	no trial data cached
Liver function test abnormal	21	24.2 15.9–36.9ROR 25.1 · χ² 445 / p 4e-99	23.8 EB05 16.4 · IC025 +3.2 3/3 methods agree	Reporting / coding artifact	serious PRR 25.6 · 100% clinician	no trial data cached
Blood cholesterol increased	29	21.0 14.7–30.0ROR 22.0 · χ² 534 / p 2e-118	20.7 EB05 15.1 · IC025 +3.4 3/3 methods agree	Lab value / disease marker	serious PRR 25.1 · 100% clinician	no trial data cached
Acute hepatic failure	8	19.9 10.0–39.6ROR 20.1 · χ² 125 / p 2e-29	18.0 EB05 8.3 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 16.8	no trial data cached
Economic problem	9	19.7 10.3–37.7ROR 20.0 · χ² 142 / p 5e-33	18.2 EB05 9.1 · IC025 +2.2 3/3 methods agree	Reporting / coding artifact	serious PRR 18.3	no trial data cached
Herpes zoster (shingles)	26	15.3 10.5–22.2ROR 15.9 · χ² 333 / p 1e-74	14.9 EB05 10.4 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 20.6 · ♀ 95% (drug 75%) · 96% clinician	no trial data cached
Leukopenia (low white blood cells)	22	14.9 9.9–22.5ROR 15.4 · χ² 272 / p 2e-61	14.4 EB05 9.7 · IC025 +2.8 3/3 methods agree	Not in label — unassessed	serious PRR 13.1 · 100% clinician	no trial data cached
Activities of daily living impaired	6	10.1 4.5–22.4ROR 10.2 · χ² 40 / p 1e-10	6.9 EB05 3.1 · IC025 +1.2 3/3 methods agree	Not in label — unassessed	serious PRR 9.6	no trial data cached
Tardive dyskinesia (persistent involuntary movements)	5	5.9 2.5–14.2ROR 6.0 · χ² 16 / p 3e-5	4.1 EB05 1.9 · IC025 +0.5	Not in label — unassessed	serious PRR 6.0	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
Blood cholesterol increased	29	21.0 14.7–30.0ROR 22.0 · χ² 534 / p 2e-118	20.7 EB05 15.1 · IC025 +3.4 3/3 methods agree	Lab value / disease marker	serious PRR 25.1 · 100% clinician	no trial data cached
Herpes zoster (shingles)	26	15.3 10.5–22.2ROR 15.9 · χ² 333 / p 1e-74	14.9 EB05 10.4 · IC025 +2.9 3/3 methods agree	Not in label — unassessed	serious PRR 20.6 · ♀ 95% (drug 75%) · 96% clinician	no trial data cached
Fibromyalgia	23	32.0 21.4–47.8ROR 33.2 · χ² 660 / p 6e-146	31.2 EB05 21.9 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 32.5 · 90% clinician	no trial data cached
Oral pain	23	34.6 23.2–51.7ROR 35.9 · χ² 717 / p 3e-158	33.7 EB05 23.6 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 53.7 · 100% clinician	no trial data cached
Leukopenia (low white blood cells)	22	14.9 9.9–22.5ROR 15.4 · χ² 272 / p 2e-61	14.4 EB05 9.7 · IC025 +2.8 3/3 methods agree	Not in label — unassessed	serious PRR 13.1 · 100% clinician	no trial data cached
Liver function test abnormal	21	24.2 15.9–36.9ROR 25.1 · χ² 445 / p 4e-99	23.8 EB05 16.4 · IC025 +3.2 3/3 methods agree	Reporting / coding artifact	serious PRR 25.6 · 100% clinician	no trial data cached
Synovitis	21	39.3 25.8–59.9ROR 40.7 · χ² 746 / p 1e-164	38.0 EB05 26.3 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 34.9 · 100% clinician	no trial data cached
Tenderness	18	58.3 37.0–92.0ROR 60.0 · χ² 956 / p 3e-210	55.0 EB05 36.8 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious n=17	no trial data cached
Economic problem	9	19.7 10.3–37.7ROR 20.0 · χ² 142 / p 5e-33	18.2 EB05 9.1 · IC025 +2.2 3/3 methods agree	Reporting / coding artifact	serious PRR 18.3	no trial data cached
Acute hepatic failure	8	19.9 10.0–39.6ROR 20.1 · χ² 125 / p 2e-29	18.0 EB05 8.3 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 16.8	no trial data cached
Activities of daily living impaired	6	10.1 4.5–22.4ROR 10.2 · χ² 40 / p 1e-10	6.9 EB05 3.1 · IC025 +1.2 3/3 methods agree	Not in label — unassessed	serious PRR 9.6	no trial data cached
Tardive dyskinesia (persistent involuntary movements)	5	5.9 2.5–14.2ROR 6.0 · χ² 16 / p 3e-5	4.1 EB05 1.9 · IC025 +0.5	Not in label — unassessed	serious PRR 6.0	no trial data cached
Extrapyramidal disorder	4	5.4 2.0–14.3ROR 5.4 · χ² 10 / p 7e-4	3.6 EB05 1.6 · IC025 +0.1	Not in label — unassessed	serious PRR 5.1	no trial data cached
Hallucination, auditory	4	8.5 3.2–22.5ROR 8.5 · χ² 19 / p 5e-6	5.0 EB05 2.1 · IC025 +0.4 3/3 methods agree	Not in label — unassessed	serious PRR 4.2	no trial data cached
Drug toxicity	4	9.8 3.7–26.0ROR 9.8 · χ² 23 / p 7e-7	5.7 EB05 2.2 · IC025 +0.5 3/3 methods agree	Not in label — unassessed	serious PRR 8.6	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.

Synovitis — n=21, PRR 39.3
Oral pain — n=23, PRR 34.6
Fibromyalgia — n=23, PRR 32.0
Herpes zoster — n=26, PRR 15.3
Leukopenia — n=22, PRR 14.9

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 Orphenadrine?

In FDA FAERS, the most frequently co-reported reaction terms for Orphenadrine are blood cholesterol increased, herpes zoster, fibromyalgia, oral pain, leukopenia, synovitis. 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 Orphenadrine have an FDA boxed warning?

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

Do FAERS signals prove that Orphenadrine 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 1cff761d-e594-a9e6-e063-6394a90a1fd5, effective 20240711; matched on openfda.generic_name.exact:"ORPHENADRINE CITRATE")
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, 20 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.