Antimuscarinic / smooth muscle relaxant Pregnancy: US Pregnancy Category B. Reproduction studies in rats and rabbits at doses up to 34 times the human dose revealed no evidence of impaired fertility or harm to the fetus, but there are no well-controlled studies in pregnant women; use during pregnancy only if clearly needed.

Flavoxate hydrochloride

Brand names: Urispas

Flavoxate hydrochloride is a smooth-muscle relaxant used to relieve urinary frequency, urgency, dysuria and bladder spasm associated with conditions such as cystitis and lower urinary tract inflammation.

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: One or two 100 mg tablets (100–200 mg) three or four times a day

Route: Oral

Frequency: Three or four times a day

The label states the same regimen for adults and children over 12 years of age: 'One or two 100 mg tablets 3 or 4 times a day.' With improvement of symptoms, the dose may be reduced. No numerical maximum daily dose is stated in the fetched label. Not recommended for infants and children under 12 years of age because safety and efficacy have not been demonstrated in this age group; safety and effectiveness in children below 12 years have not been established. SOURCE CAVEAT: no UK SPC (eMC) was retrieved for this bundle — the only labelling fetched is the US FDA prescribing information (FLAVOXATE HYDROCHLORIDE, Padagis US LLC, label date 2023-05-31, DailyMed setid ff1c0ee9-75d2-478a-9152-0753be81ff11). UK posology may differ; a clinician must verify against the UK SPC before publication.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Pyloric or duodenal obstruction
Obstructive intestinal lesions or ileus
Achalasia
Gastrointestinal haemorrhage
Obstructive uropathies of the lower urinary tract

Side effects

Gastrointestinal: nausea, vomiting, dry mouth
CNS: vertigo, headache, mental confusion (especially in the elderly), drowsiness, nervousness
Ophthalmic: blurred vision, disturbance in eye accommodation, increased ocular tension
Cardiovascular: tachycardia and palpitation
Allergic: urticaria and other dermatoses, eosinophilia and hyperpyrexia; also leukopenia (one reversible case) and dysuria

Clinical monograph

How it works

It exerts a direct antispasmodic action on urinary tract smooth muscle, with antimuscarinic and local anaesthetic properties, reducing detrusor overactivity.

Prescribing in practice

It is contraindicated in gastrointestinal or urinary tract obstruction and should be avoided where antimuscarinic effects are hazardous, such as glaucoma.
Anticholinergic effects including dry mouth, blurred vision and drowsiness may occur.
It does not treat the underlying cause of infection, so appropriate investigation and treatment of any infection are still required.

Monitoring

Monitor symptomatic response and anticholinergic adverse effects, ensuring any underlying urinary infection is treated appropriately.

Counselling the patient

This medicine eases bladder discomfort but does not replace treatment of any infection.
It may cause drowsiness or blurred vision; take care with driving and skilled tasks.
Report difficulty passing urine or worsening symptoms.

Evidence & guidelines

Flavoxate is an established symptomatic treatment for lower urinary tract spasm, used in line with the current prescribing references.

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.

Pathways