Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Overactive-bladder pharmacotherapy
Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Retention or serious medicine toxicity
New painful inability to void, severe abdominal distension, acute confusion, collapse, suspected angle-closure glaucoma, hypertensive crisis, arrhythmia, severe constipation with obstruction or hypersensitivity after an OAB medicine requires urgent assessment.
Action: Stop the suspected medicine when clinically appropriate, assess observations, cognition, abdomen, bladder residual, bowel function, blood pressure and ECG or eye symptoms as indicated, and obtain urgent medical, urological or ophthalmic care rather than waiting for a routine efficacy review.
Purpose and principles
Select and monitor antimuscarinic or beta-3-agonist treatment after appropriate behavioural care, using current UK doses, contraindications, interaction checks and structured review.
Medicine is one part of overactive-bladder care. Before prescribing, confirm urgency, usually with frequency or nocturia, and examine whether infection, excessive urine production, high residual, pelvic-organ prolapse, a medicine or neurological disease better explains the presentation. A three-day diary and a genuine trial of bladder training provide a baseline. Medicine should improve the outcome the person values, not merely reduce one diary number.
Antimuscarinics reduce muscarinic signalling to the detrusor during storage. Class effects include dry mouth, constipation, blurred vision, tachycardia, impaired sweating and urinary retention. Central cognitive effects vary by drug, dose, blood-brain penetration and vulnerability; NICE notes uncertainty about long-term cognitive effects and requires consideration of cognition, dementia risk and total anticholinergic load. Check other drugs with anticholinergic activity rather than assessing the bladder prescription in isolation.
Indications, selection and cautions
Appropriate medicine candidate
Urgency or urgency leakage remains bothersome after bladder training, infection and important emptying problems have been addressed, and a measurable goal is agreed.
High anticholinergic vulnerability
Frailty, cognitive impairment, falls, constipation, glaucoma risk, myasthenia, impaired gastric motility or multiple anticholinergic medicines increases harm.
Retention vulnerability
Weak stream, residual urine, bladder-outlet obstruction or significant prolapse makes both antimuscarinic and beta-3 treatment require careful monitoring.
Cardiovascular constraint
Uncontrolled hypertension, arrhythmia, recent myocardial or cerebrovascular events and interacting medicines influence beta-3-agonist selection.
Treatment response
Fewer urgency leaks, longer manageable intervals, improved sleep or restored activity with acceptable adverse effects constitutes benefit; dry mouth alone does not.
Red flags requiring action
Painful retention, rapidly rising residual, anuria or renal impairment after treatment requires urgent bladder and urological assessment.
A painful red eye, blurred vision or halos with an antimuscarinic raises concern for acute angle closure and needs emergency ophthalmic review.
Severe headache, chest pain, neurological symptoms or blood pressure at hypertensive-crisis levels while taking mirabegron requires immediate assessment.
Assessment before treatment
01Three-day bladder diaryFirst step
Why
Confirm the storage pattern and establish baseline frequency, urgency, leakage and nocturia.
Interpretation and limitations
A later diary allows like-for-like response assessment; high urine volume or voiding symptoms should redirect the plan before dose escalation.
02Urinalysis and culture when indicated
Why
Exclude infection and identify blood, glucose or protein that needs a different pathway.
Interpretation and limitations
Treat symptomatic infection appropriately; do not repeatedly prescribe antibiotics for stable OAB without evidence.
03Medicine and anticholinergic-burden review
Why
Identify additive cognitive, bowel, ocular, cardiac and retention risks and important metabolic interactions.
Interpretation and limitations
Reducing another causative medicine or choosing a beta-3 agonist may provide more net benefit than adding a higher antimuscarinic dose.
04Blood pressure and pulse
Why
Establish cardiovascular safety before mirabegron and monitor during treatment; consider for other agents according to risk.
Interpretation and limitations
Do not use mirabegron at systolic pressure at least 180 mmHg or diastolic pressure at least 110 mmHg; investigate symptomatic or substantial rises.
Treatment approach
01Before prescribingConfirm indication and modifiersFirst stepBladder training has not adequately controlled bothersome urgency or frequency.+
1Recheck diary, urinalysis, emptying symptoms, fluid pattern, constipation, prolapse, neurological features and the person's treatment goal.
2Review cognition, frailty, falls, glaucoma, bowel disease, myasthenia, renal and hepatic function, blood pressure, pregnancy and every interacting medicine.
3Explain likely benefit, delayed onset, adverse effects and alternatives, then select the lowest-cost suitable anticholinergic or a NICE-indicated beta-3 agonist.
02Early reviewAssess benefit and harm at four weeksA new OAB medicine or dose has been started.+
1Compare urgency, leakage, frequency, nocturia and valued activities with baseline, allowing for the expected time to benefit.
Regimens, contraindications and interactions
A low-cost antimuscarinic option for adult overactive bladder, but NICE says not to offer the immediate-release formulation to older women at higher risk of sudden physical or mental deterioration.
Oxybutynin immediate release
Start 2.5 mg orally three times daily and titrate according to response and adverse effects up to 5 mg four times daily. In older or frail adults, start 2.5 mg twice daily and, if needed and tolerated, increase to 5 mg twice daily.
Contraindicated in myasthenia gravis, narrow-angle glaucoma or a shallow anterior chamber, gastrointestinal obstruction or atony, severe ulcerative colitis or toxic megacolon, and bladder-outlet obstruction with retention risk. Review cognitive effects, constipation, heat intolerance, blurred vision and additive anticholinergic or CYP3A4 interactions.
A once-daily antimuscarinic option selected within the NICE lowest-cost suitable drug pathway and reviewed after four weeks.
Solifenacin
Take 5 mg orally once daily; if needed and tolerated, increase to 10 mg once daily. Do not exceed 5 mg daily with creatinine clearance 30 mL/min or less, moderate hepatic impairment, or a potent CYP3A4 inhibitor.
Contraindicated in urinary retention, severe gastrointestinal disease or toxic megacolon, myasthenia gravis, narrow-angle glaucoma risk, dialysis and severe hepatic impairment. Avoid a potent CYP3A4 inhibitor with severe renal or moderate hepatic impairment; consider QT-risk factors, constipation and cognitive or cumulative anticholinergic effects.
Complications, monitoring and follow-up
Review four weeks after each new medicine or dose change, earlier when adverse effects are unacceptable.
Track urgency leakage, frequency, nocturia, diary volumes and the person's functional target rather than escalating solely for persistent awareness of urgency.
Monitor bowel function, dry mouth, vision, cognition, falls, heat intolerance and residual symptoms with antimuscarinics.
Check blood pressure with mirabegron and review pulse, palpitations and cardiovascular symptoms with any clinically relevant risk.
Reassess long-term need annually and every six months for people older than 75, including renal or hepatic change, interactions and anticholinergic burden.
Special situations
Four weeks is a safety checkpoint
The early review is long enough for emerging benefit but soon enough to detect retention, cognitive harm, constipation or uncontrolled blood pressure.
Lowest cost still means suitable
NICE cost sequencing follows clinical contraindication and vulnerability; it does not require oxybutynin in a frail older person at high cognitive risk.
Class choice is not binary
Different antimuscarinics have different formulations and clearance, while mirabegron and vibegron have distinct cardiovascular and interaction profiles.
Dry mouth is not the outcome
Antimuscarinic effects may show exposure but only improvement in symptoms or function justifies continuing treatment.
Medicine does not replace training
Bladder training, bowel care and practical access remain useful when a drug is added and after it is stopped.
Common pitfalls
01
Starting medicine before excluding infection, high urine output or clinically important incomplete emptying.
02
Offering immediate-release oxybutynin to a vulnerable older woman without considering sudden cognitive or physical deterioration.
03
Treating beta-3 agonists as free from retention, cardiovascular or interaction risk.
04
Using mirabegron without baseline and follow-up blood pressure or despite severe uncontrolled hypertension.
05
Escalating doses indefinitely without a four-week response review and a clear functional target.
06
Continuing several anticholinergic medicines after benefit has disappeared or frailty and renal function have changed.
Practice
Two practice questions
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Question 1 of 2
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Obstetrics and gynaecologyOriginal SBA
Anticholinergic choice in a vulnerable older woman
An 82-year-old with urgency incontinence, falls and mild cognitive impairment is considering medicine after bladder training. Which prescribing principle is most appropriate?
Sources and review status8 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
NICE recommends a suitable anticholinergic with the lowest acquisition cost, followed by another low-cost option if the first is ineffective or poorly tolerated. Immediate-release oxybutynin has a licensed regimen but should not be offered to older women at higher risk of sudden physical or mental deterioration. Transdermal treatment can be considered when oral anticholinergic treatment is not tolerated. Flavoxate, propantheline and imipramine should not be used for OAB or urinary incontinence.
Beta-3 agonists relax the detrusor through adrenergic signalling and avoid much of the antimuscarinic burden, but they are not safety-free. NICE recommends mirabegron or vibegron when antimuscarinics are contraindicated, clinically ineffective or cause unacceptable effects. Mirabegron can raise blood pressure and is contraindicated in severe uncontrolled hypertension. Vibegron has fewer formal contraindications but still requires attention to retention and P-glycoprotein substrates such as digoxin.
Choice is individual. Constipation, narrow-angle glaucoma risk, myasthenia, poor emptying and cognitive vulnerability may make an antimuscarinic unattractive. Uncontrolled hypertension or interacting cardiovascular medicines may limit mirabegron. Renal and hepatic function changes the dose or suitability of several products. Pregnancy and breastfeeding require product-specific review; OAB drug treatment is usually deferred unless a specialist determines that benefit justifies uncertainty or risk.
Set expectations before the first dose. Substantial benefit may take at least four weeks and complete dryness is not guaranteed. Agree a four-week review after initiation or dose change, with earlier contact for adverse effects. At review, compare urgency, leakage, frequency, nocturia and functional goals; check blood pressure or residual where relevant; and stop a medicine that offers no worthwhile benefit rather than accumulating drugs indefinitely.
Long-term review remains active. NICE recommends at least annual review and every six months for people older than 75. Reassess anticholinergic burden, cognition, falls, bowel function, blood pressure, renal and hepatic function, interactions and continuing need. Referral is appropriate when adequate behavioural and medicine trials fail, adverse effects prevent treatment, emptying is impaired or invasive options are being considered.
Key points
Use OAB medicine after bladder training has been offered and urgency or frequency remains troublesome; confirm infection, emptying and the diagnosis before escalation.
Explain that benefit varies, may take at least four weeks, and antimuscarinic dry mouth and constipation are common rather than evidence of an allergy.
Review frailty, cognition, glaucoma, gastric motility, bowel obstruction, myasthenia, residual urine, renal and hepatic function, blood pressure and total anticholinergic burden.
NICE advises the lowest-acquisition-cost suitable anticholinergic first; do not offer flavoxate, propantheline or imipramine for OAB or urinary incontinence.
Do not offer immediate-release oxybutynin to an older woman at higher risk of sudden physical or mental deterioration.
Mirabegron and vibegron are NICE options when antimuscarinics are unsuitable, insufficiently effective or cause unacceptable adverse effects, subject to their individual licences.
Review four weeks after every new medicine or dose change, sooner for adverse effects; review long-term treatment annually, or every six months when older than 75.
Stop ineffective treatment, switch within the pathway or refer after unsuccessful or intolerable medicine trials; retain bladder training and safety-netting.
New delirium, hallucinations, falls, severe constipation or heat intolerance may reflect clinically important anticholinergic toxicity.
Facial swelling, breathing difficulty, widespread rash or another serious hypersensitivity reaction requires emergency treatment.
05Renal, hepatic and residual assessment
Why
Select the licensed dose and detect impaired clearance or emptying when history or comorbidity indicates.
Interpretation and limitations
Apply product-specific adjustments rather than a class rule; worsening emptying can require treatment cessation and urgent review.
2
Ask specifically about dry mouth, constipation, vision, cognition, falls, palpitations and emptying; check blood pressure or residual when relevant.
3Continue, adjust, switch or stop through shared decision making, avoiding automatic polypharmacy when benefit is absent.
03Persistent symptomsRefer rather than accumulate harmBehavioural treatment and suitable medicines are ineffective, contraindicated or intolerable.+
1Confirm adherence and diagnosis, treat contributing constipation or infection and ensure the residual and diary do not show a different mechanism.
2Refer to specialist care for urodynamic consideration and discussion of botulinum toxin, neuromodulation or other advanced options.
3Maintain containment, bladder training and an explicit retention and infection safety-net during the referral period.
A NICE-recommended beta-3 agonist when antimuscarinics are contraindicated, insufficiently effective or have unacceptable adverse effects.
Mirabegron modified release
Take 50 mg orally once daily. Use 25 mg once daily with estimated GFR 15–29 mL/min/1.73 m² or moderate hepatic impairment; product-specific reductions or avoidance also apply with strong CYP3A4 inhibitors. Do not use in end-stage renal disease or severe hepatic impairment.
Contraindicated in severe uncontrolled hypertension, defined as systolic blood pressure at least 180 mmHg or diastolic at least 110 mmHg. Measure blood pressure before and periodically during treatment; data are limited in stage 2 hypertension, at least 160 mmHg systolic or 100 mmHg diastolic. Monitor retention with outlet obstruction or antimuscarinic co-treatment and review CYP2D6, digoxin and other P-glycoprotein interactions.
A NICE-recommended beta-3 agonist for adults when antimuscarinics are unsuitable, insufficiently effective or cause unacceptable adverse effects.
Vibegron
Take 75 mg orally once daily, with or without food. No adjustment is required with estimated GFR above 15 and below 90 mL/min/1.73 m² or mild to moderate hepatic impairment; it is not recommended in end-stage renal disease or severe hepatic impairment.
Monitor for urinary retention, especially with bladder-outlet obstruction or concurrent antimuscarinic treatment, and stop if retention develops. Check digoxin levels and dose because exposure can rise; consider other narrow-therapeutic-index P-glycoprotein substrates. Vibegron is not recommended during pregnancy and should be stopped when pregnancy is planned or diagnosed; it should not be used during breastfeeding according to the current product information.