Antimuscarinic (overactive bladder) Pregnancy: There are no adequate data on the use of oxybutynin in pregnant women and animal studies have shown minor reproductive toxicity; oxybutynin is not recommended during pregnancy. Breastfeeding: a small amount is excreted in breast milk and the effect on newborns/infants is unknown, so use during breastfeeding is not recommended.

Oxybutynin hydrochloride

Brand names: Ditropan, Cystrin, Lyrinel XL

Oxybutynin hydrochloride is the oral salt of the antimuscarinic oxybutynin, used for overactive bladder and urgency incontinence, and also for neurogenic bladder instability; immediate- and modified-release tablets are available.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Prolonged-release tablets: starting dose 5 mg once daily; after at least one week on 5 mg daily the dose may be increased to 10 mg once daily, with subsequent incremental increases or decreases of 5 mg/day

Route: Oral — prolonged-release tablet, swallowed whole with the aid of liquid; must not be chewed, divided or crushed

Frequency: Once daily

Max: Total daily dose should not exceed 20 mg

There should be an interval of at least one week between dose changes; titrate to the minimum dose that achieves an optimal balance of efficacy and tolerability. May be administered with or without food. Elderly: no dosage adjustment is necessary, but use with caution in the frail elderly and in elderly patients generally because of the risk of cognitive impairment (§4.4). For patients currently taking immediate-release oxybutynin, clinical judgement should be exercised in selecting the appropriate prolonged-release dose, taking the current immediate-release dose into account. In case of a missed dose, the patient should wait and take the next dose at the regular time. Paediatric (non-weight-based, so not captured as a per-kg dose): children over the age of 5 years — initial dose 5 mg once a day, increased in 5 mg increments up to a maximum of 15 mg once a day; should not be used in children below the age of 5 years because safety and efficacy have not been established. FORMULATION CAVEAT: the only UK SPC fetched is 'Oxybutynin hydrochloride 10 mg prolonged-release tablets' (eMC product 15797). The regimen above is the PROLONGED-RELEASE regimen only — the immediate-release oral (and transdermal) posology was NOT retrieved and a clinician must source it separately if the page covers those formulations. Note also that §4.4 and §4.8 in this bundle were truncated at the source-fetch limit.

Dose adjustments

Renal

No numerical dose adjustment is stated. §4.4: oxybutynin should be given with caution in patients with hepatic or renal impairment. Contraindicated where urinary frequency and nocturia are due to heart or renal failure.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Narrow-angle glaucoma or shallow anterior chamber
Myasthenia gravis
Urinary retention
Gastrointestinal obstructive disorder, paralytic ileus or intestinal atony
Severe ulcerative colitis
Toxic megacolon
Urinary frequency and nocturia due to heart or renal failure
Porphyria

Side effects

Dry mouth (very common)
Constipation, diarrhoea and nausea (common)
Headache, somnolence and dizziness (common)
Blurred vision and dry eye (common); angle-closure glaucoma reported
Anticholinergic CNS effects — hallucinations, agitation, confusional state, memory impairment (uncommon); angioedema of the face, lips, tongue and/or larynx has been reported, sometimes after the first dose

Clinical monograph

How it works

It blocks muscarinic M3 receptors on the detrusor and exerts a direct smooth-muscle relaxant effect, suppressing unstable detrusor contractions and raising functional bladder capacity.

Prescribing in practice

In elderly and cognitively vulnerable patients immediate-release oxybutynin can cause confusion and worsen cognition, so it is best avoided or replaced with a better-tolerated alternative in this group.
Contraindicated in untreated angle-closure glaucoma, urinary retention, bladder outflow obstruction and gastrointestinal obstruction or atony.
Expect anticholinergic effects such as dry mouth and constipation; modified-release formulation can reduce peak-related side effects.

Monitoring

Assess symptom control and tolerability after a treatment trial, monitoring cognition in the elderly and bowel function.

Counselling the patient

Swallow modified-release tablets whole without crushing.
Expect dry mouth; report blurred vision, eye pain or inability to pass urine.

Evidence & guidelines

Oxybutynin is well established for overactive and neurogenic bladder, with NICE cautioning against immediate-release oxybutynin as first-line in frail older women.

Reference: NICE NG123; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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