Oxybutynin side effects: what 29,101 FDA adverse event reports show
Drug class
Muscarinic antagonist
Who reports
29,101 reports · 47% serious · 1,696 with death outcome · 78% female
Used for
Oxybutynin chloride is a muscarinic antagonist indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. ( 1 ) Oxybutynin chloride extended-release tablets are also indicated for the treatment of pediatric patients aged 6 years and older with symptoms of detrusor overactivity associated with a neurological condition (e.g., spina bifida).
What it is
Oxybutynin chloride extended-release tablets are an antispasmodic, muscarinic antagonist. Each oxybutynin chloride extended-release tablets contains 5 mg, 10 mg, or 15 mg of oxybutynin chloride USP, formulated as a once-a-day controlled-release tablet for oral administration.
Boxed warning
None in the current label
Causality screen of the 40 strongest signals
What the badges mean
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- 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.
- 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, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,122 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Vaginal flatulence | 50 | 140.9 104.0–190.8ROR 141.1 · calibrated p 2e-8 ✓ | 112.7 EB05 88.9 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious n=50 · ♀ 100% (drug 78%) | not reported in cached trials |
| Product closure removal difficult | 71 | 54.9 43.1–69.9ROR 55.0 · calibrated p 1e-5 ✓ | 50.4 EB05 41.3 · IC025 +4.8 3/3 methods agree | Reporting / coding artifact | ♀ 100% (drug 78%) · 100% consumer | not reported in cached trials |
| Anticholinergic syndrome | 72 | 34.1 26.9–43.1ROR 34.1 · calibrated p 2e-4 ✓ | 32.3 EB05 26.5 · IC025 +4.3 3/3 methods agree | Labeled (related wording) related wording | serious n=72 · ♀ 45% (drug 78%) | not reported in cached trials |
| Application site erythema | 927 | 26.3 24.6–28.0ROR 27.1 · calibrated p 4e-4 ✓ | 25.4 EB05 24.0 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=19 · ♀ 98% (drug 78%) · 94% consumer | NCT04534491: 9/785 (1.1%) on Oxybutynin |
| Hypertonic bladder | 97 | 25.1 20.5–30.7ROR 25.2 · calibrated p 7e-4 ✓ | 24.2 EB05 20.4 · IC025 +4.1 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=63 | NCT04534491: 5/785 (0.6%) on Oxybutynin |
| Bladder spasm | 59 | 23.6 18.2–30.5ROR 23.6 · calibrated p 0.001 ✓ | 22.7 EB05 18.2 · IC025 +3.8 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=41 | not reported in cached trials |
| Female genital tract fistula | 50 | 21.5 16.3–28.5ROR 21.6 · calibrated p 0.002 ✓ | 20.8 EB05 16.4 · IC025 +3.7 3/3 methods agree | Not in label — unassessed | serious n=50 · ♀ 100% (drug 78%) | not reported in cached trials |
| Urine leukocyte esterase positive | 20 | 20.9 13.4–32.6ROR 20.9 · calibrated p 0.003 ✓ | 19.9 EB05 13.5 · IC025 +3.0 3/3 methods agree | Lab value / disease marker | serious n=16 | not reported in cached trials |
| Chronic kidney disease-mineral and bone disorder | 30 | 20.6 14.4–29.7ROR 20.7 · calibrated p 0.002 ✓ | 19.8 EB05 14.5 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=30 | not reported in cached trials |
| Application site pruritus | 615 | 20.0 18.5–21.7ROR 20.5 · calibrated p 0.002 ✓ | 19.5 EB05 18.2 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=11 · ♀ 98% (drug 78%) · 95% consumer | NCT04534491: 8/785 (1.0%) on Oxybutynin |
| Application site papules | 28 | 19.6 13.5–28.6ROR 19.6 · calibrated p 0.003 ✓ | 18.9 EB05 13.6 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | ♀ 100% (drug 78%) · 100% consumer | not reported in cached trials |
| Application site rash | 351 | 18.8 16.9–20.9ROR 19.0 · calibrated p 0.003 ✓ | 18.3 EB05 16.8 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | 94% consumer | NCT04534491: 4/785 (0.5%) on Oxybutynin |
| Urinary sediment present | 16 | 18.4 11.2–30.2ROR 18.4 · calibrated p 0.005 ✓ | 17.4 EB05 10.9 · IC025 +2.7 3/3 methods agree | Lab value / disease marker | serious n=12 | not reported in cached trials |
| Application site warmth | 31 | 17.8 12.5–25.5ROR 17.9 · calibrated p 0.004 ✓ | 17.2 EB05 12.6 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | ♀ 100% (drug 78%) · 100% consumer | not reported in cached trials |
| Product adhesion issue | 827 | 17.2 16.1–18.4ROR 17.7 · calibrated p 0.003 ✓ | 16.8 EB05 15.9 · IC025 +3.9 3/3 methods agree | Reporting / coding artifact | serious n=15 · 96% consumer | not reported in cached trials |
| Application site discomfort | 42 | 17.2 12.6–23.3ROR 17.2 · calibrated p 0.005 ✓ | 16.6 EB05 12.7 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | ♀ 100% (drug 78%) · 100% consumer | not reported in cached trials |
| Radiculopathy | 60 | 16.8 13.0–21.6ROR 16.8 · calibrated p 0.005 ✓ | 16.3 EB05 13.1 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=59 · ♀ 100% (drug 78%) | not reported in cached trials |
| Monocyte percentage increased | 15 | 15.6 9.3–26.0ROR 15.6 · calibrated p 0.010 ✓ | 14.4 EB05 8.6 · IC025 +2.5 3/3 methods agree | Lab value / disease marker | serious n=14 | not reported in cached trials |
| Application site discolouration | 81 | 14.6 11.7–18.2ROR 14.6 · calibrated p 0.008 ✓ | 14.2 EB05 11.8 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | 100% consumer | not reported in cached trials |
| Application site burn | 98 | 14.5 11.9–17.7ROR 14.6 · calibrated p 0.008 ✓ | 14.2 EB05 11.9 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | ♀ 100% (drug 78%) · 100% consumer | not reported in cached trials |
| Application site bruise | 19 | 14.4 9.1–22.6ROR 14.4 · calibrated p 0.012 ✓ | 13.4 EB05 8.6 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | – | not reported in cached trials |
| Neurogenic bladder | 41 | 14.2 10.4–19.3ROR 14.2 · calibrated p 0.010 ✓ | 13.7 EB05 10.4 · IC025 +3.1 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=35 | not reported in cached trials |
| Application site inflammation | 26 | 13.9 9.4–20.5ROR 13.9 · calibrated p 0.012 ✓ | 13.2 EB05 9.1 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | ♀ 100% (drug 78%) · 100% consumer | not reported in cached trials |
| Nephrogenic anaemia | 88 | 13.8 11.2–17.0ROR 13.8 · calibrated p 0.010 ✓ | 13.5 EB05 11.2 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=88 | not reported in cached trials |
| Red blood cells urine positive | 18 | 13.6 8.5–21.7ROR 13.6 · calibrated p 0.015 ✓ | 12.5 EB05 7.8 · IC025 +2.5 3/3 methods agree | Lab value / disease marker | serious n=16 | not reported in cached trials |
| Proctitis | 51 | 13.3 10.1–17.6ROR 13.3 · calibrated p 0.013 ✓ | 12.9 EB05 10.1 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=50 · ♀ 100% (drug 78%) | not reported in cached trials |
| Drug administered at inappropriate site | 192 | 13.2 11.4–15.2ROR 13.2 · calibrated p 0.012 ✓ | 12.9 EB05 11.4 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | ♀ 100% (drug 78%) · 94% consumer | not reported in cached trials |
| Application site irritation | 206 | 12.1 10.6–13.9ROR 12.2 · calibrated p 0.016 ✓ | 11.9 EB05 10.6 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | 95% consumer | NCT04534491: 142/785 (18.1%) on Oxybutynin |
| Drug effect delayed | 76 | 12.1 9.6–15.2ROR 12.1 · calibrated p 0.017 ✓ | 11.7 EB05 9.6 · IC025 +3.1 3/3 methods agree | Reporting / coding artifact | 100% consumer | not reported in cached trials |
| Hyperparathyroidism secondary | 41 | 11.8 8.7–16.1ROR 11.9 · calibrated p 0.020 ✓ | 11.3 EB05 8.5 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=41 | not reported in cached trials |
| Drug effect variable | 18 | 11.5 7.2–18.3ROR 11.5 · calibrated p 0.027 ✓ | 10.2 EB05 6.4 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | – | not reported in cached trials |
| Bladder catheterisation | 15 | 11.3 6.8–18.9ROR 11.3 · calibrated p 0.029 ✓ | 9.8 EB05 5.9 · IC025 +2.2 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=11 | not reported in cached trials |
| Application site erosion | 20 | 11.3 7.3–17.6ROR 11.3 · calibrated p 0.027 ✓ | 10.2 EB05 6.6 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | – | not reported in cached trials |
| Dry age-related macular degeneration | 17 | 11.2 6.9–18.1ROR 11.2 · calibrated p 0.029 ✓ | 9.9 EB05 6.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious n=17 | not reported in cached trials |
| Culture urine positive | 21 | 10.9 7.1–16.7ROR 10.9 · calibrated p 0.031 ✓ | 9.8 EB05 6.4 · IC025 +2.4 3/3 methods agree | Lab value / disease marker | serious n=17 | not reported in cached trials |
| Secondary progressive multiple sclerosis | 27 | 10.4 7.1–15.2ROR 10.4 · calibrated p 0.034 ✓ | 9.5 EB05 6.6 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=22 · ♀ 100% (drug 78%) | not reported in cached trials |
| Bladder pain | 43 | 9.9 7.4–13.4ROR 10.0 · calibrated p 0.037 ✓ | 9.3 EB05 7.1 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious n=21 · 74% consumer | not reported in cached trials |
| Bladder dysfunction | 14 | 9.9 5.9–16.8ROR 9.9 · calibrated p 0.045 ✓ | 8.3 EB05 5.0 · IC025 +2.0 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=11 | not reported in cached trials |
| White blood cells urine positive | 25 | 9.8 6.6–14.5ROR 9.8 · calibrated p 0.042 ✓ | 8.8 EB05 6.1 · IC025 +2.4 3/3 methods agree | Lab value / disease marker | serious n=19 · ♀ 100% (drug 78%) | not reported in cached trials |
| Lymphocyte percentage decreased | 18 | 9.7 6.1–15.5ROR 9.7 · calibrated p 0.045 ✓ | 8.5 EB05 5.4 · IC025 +2.2 3/3 methods agree | Lab value / disease marker | serious n=17 | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Oxybutynin as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (5 of 40 signal terms matched).
- NCT04534491 — Study to Gather Information About the Actual Use of an Adhesive Patch Placed on the Skin to Deliver Oxytrol Th (N=855, PHASE3; 139 AE terms posted; arms: Oxybutynin (Oxytrol, BAY839380))
- NCT00350636 — A Comparison of a New Drug to Treat Overactive Bladder vs. Placebo (N=789, PHASE3; 30 AE terms posted; arms: Oxybutynin Topical Gel; Placebo Topical Gel)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
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) | 3,970 | 2.2 2.1–2.2ROR 2.4 · calibrated p 0.874 | 2.2 EB05 2.1 · IC025 +1.1 3/3 methods agree | Reporting / coding artifact | serious PRR 1.1 · 85% consumer | not reported in cached trials |
| Fatigue (tiredness) | 1,570 | 1.5 1.4–1.5ROR 1.5 · calibrated p 0.631 | 1.5 EB05 1.4 · IC025 +0.5 | Labeled adverse reaction exact term | serious PRR 1.8 | NCT04534491: 11/785 (1.4%) on Oxybutynin |
| Fall | 1,491 | 3.2 3.1–3.4ROR 3.4 · calibrated p 0.520 | 3.2 EB05 3.1 · IC025 +1.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.5 | NCT04534491: 3/785 (0.4%) on Oxybutynin |
| Off label use (used outside approved label) | 1,290 | 1.1 1.0–1.1ROR 1.1 · calibrated p 0.356 | 1.1 EB05 1.0 · IC025 +0.0 | Reporting / coding artifact | serious PRR 1.1 | not reported in cached trials |
| Nausea | 1,240 | 1.1 1.1–1.2ROR 1.1 · calibrated p 0.399 | 1.1 EB05 1.1 · IC025 +0.1 | Labeled adverse reaction exact term | serious PRR 1.5 | NCT04534491: 16/785 (2.0%) on Oxybutynin |
| Dizziness | 1,164 | 1.7 1.6–1.8ROR 1.7 · calibrated p 0.778 | 1.7 EB05 1.6 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 2.0 | NCT04534491: 15/785 (1.9%) on Oxybutynin |
| Diarrhoea (diarrhea) | 1,116 | 1.3 1.2–1.3ROR 1.3 · calibrated p 0.481 | 1.3 EB05 1.2 · IC025 +0.2 | Labeled adverse reaction exact term | serious PRR 1.5 | NCT04534491: 1/785 (0.1%) on Oxybutynin (serious AE) |
| Pain | 1,103 | 1.3 1.2–1.4ROR 1.3 · calibrated p 0.511 | 1.3 EB05 1.2 · IC025 +0.3 | Labeled adverse reaction exact term | serious PRR 1.6 | NCT04534491: 2/785 (0.3%) on Oxybutynin (serious AE) |
| Urinary tract infection (bladder infection) | 1,061 | 4.5 4.3–4.8ROR 4.6 · calibrated p 0.276 | 4.5 EB05 4.3 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.6 | NCT04534491: 3/785 (0.4%) on Oxybutynin (serious AE) |
| Headache | 1,015 | 1.2 1.1–1.2ROR 1.2 · calibrated p 0.423 | 1.2 EB05 1.1 · IC025 +0.1 | Labeled adverse reaction exact term | serious PRR 1.6 | NCT04534491: 20/785 (2.5%) on Oxybutynin |
| Pruritus (itching) | 1,006 | 1.9 1.8–2.0ROR 2.0 · calibrated p 0.918 | 1.9 EB05 1.8 · IC025 +0.8 | Labeled adverse reaction exact term | serious PRR 1.2 · 79% consumer | NCT04534491: 8/785 (1.0%) on Oxybutynin |
| Application site erythema | 927 | 26.3 24.6–28.0ROR 27.1 · calibrated p 4e-4 ✓ | 25.4 EB05 24.0 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=19 · ♀ 98% (drug 78%) · 94% consumer | NCT04534491: 9/785 (1.1%) on Oxybutynin |
| Asthenia (weakness) | 906 | 1.7 1.6–1.9ROR 1.8 · calibrated p 0.807 | 1.7 EB05 1.6 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 2.2 | not reported in cached trials |
| Rash | 830 | 1.4 1.3–1.5ROR 1.4 · calibrated p 0.570 | 1.4 EB05 1.3 · IC025 +0.3 | Labeled adverse reaction exact term | serious PRR 1.1 · 72% consumer | NCT04534491: 4/785 (0.5%) on Oxybutynin |
| Product adhesion issue | 827 | 17.2 16.1–18.4ROR 17.7 · calibrated p 0.003 ✓ | 16.8 EB05 15.9 · IC025 +3.9 3/3 methods agree | Reporting / coding artifact | serious n=15 · 96% consumer | not reported in cached trials |
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.
- Vaginal flatulence — n=50, PRR 140.9
- Application site erythema — n=927, PRR 26.3 (also seen in trial arm)
- Female genital tract fistula — n=50, PRR 21.5
- Chronic kidney disease-mineral and bone disorder — n=30, PRR 20.6
- Application site pruritus — n=615, PRR 20.0 (also seen in trial arm)
- Application site papules — n=28, PRR 19.6
- Application site rash — n=351, PRR 18.8 (also seen in trial arm)
- Application site warmth — n=31, PRR 17.8
- Application site discomfort — n=42, PRR 17.2
- Radiculopathy — n=60, PRR 16.8
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 Oxybutynin?
In FDA FAERS, the most frequently co-reported reaction terms for Oxybutynin are fatigue, fall, nausea, dizziness, diarrhoea, pain. 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 Oxybutynin have an FDA boxed warning?
No. The FDA label retrieved for Oxybutynin has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Oxybutynin 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 1f95920c-5dc2-44e4-b61d-b2c5e05390ba, effective 20230206; matched on
openfda.generic_name.exact:"OXYBUTYNIN") - 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, 1,162 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 - ClinicalTrials.gov API v2 (query
OXYBUTYNIN, results-bearing studies sorted by enrollment)
Page generated 2026-10-14. 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.