α1A-selective adrenergic antagonist Pregnancy: Tamsulosin is not indicated for use in women. Ejaculation disorders, retrograde ejaculation and ejaculation failure have been observed in clinical studies and reported post-authorisation.

Tamsulosin hydrochloride

Brand names: Flomax, Flomaxtra

Tamsulosin is a uroselective alpha-1A adrenoceptor blocker used to relieve the lower urinary tract symptoms of benign prostatic hyperplasia.

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 400 microgram prolonged-release tablet daily

Route: Oral — the tablet should be swallowed whole and should not be crushed or chewed, as this will interfere with the prolonged release of the active ingredient

Frequency: Once daily

The UK SPC fetched is Faramsil 400 microgram Prolonged-release Tablets (eMC product 4948); its §4.2 states simply 'One tablet daily can be taken independently of food' — the 400 microgram strength comes from the product name, and no higher dose or titration step is stated in the UK SPC. Renal impairment: no dose adjustment is required. Hepatic impairment: no dose adjustment is required in mild to moderate hepatic impairment (severe hepatic insufficiency is a contraindication). Paediatric population: safety and efficacy in children <18 years have not been established. §4.4: treatment of patients with severe renal impairment (creatinine clearance less than 10 mL/min) should be approached with caution as these patients have not been studied; initiation of therapy is not recommended in patients scheduled for cataract or glaucoma surgery because of Intraoperative Floppy Iris Syndrome. Note §4.5 was truncated at the source-fetch limit. Cross-check only (US labelling, not UK): tamsulosin hydrochloride capsules 0.4 mg once daily approximately one-half hour after the same meal each day, increased to 0.8 mg once daily in patients who fail to respond to 0.4 mg after 2 to 4 weeks; if dosing is interrupted for several days, restart at 0.4 mg once daily.

Dose adjustments

Renal

No dose adjustment is required in patients with renal impairment. Treatment of patients with severe renal impairment (creatinine clearance less than 10 mL/min) should be approached with caution as these patients have not been studied (§4.4).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; 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.

US labelling (FDA)

Reference — US labelling, may differ from UK

Tamsulosin hydrochloride capsules 0.4 mg once daily is recommended as the dose for the treatment of the signs and symptoms of BPH. It should be administered approximately one-half hour following the same meal each day. Tamsulosin hydrochloride capsules should not be crushed, chewed or opened. For those patients who fail to respond to the 0.4 mg dose after 2 to 4 weeks of dosing, the dose of tamsulosin hydrochloride capsules can be increased to 0.8 mg once daily. Tamsulosin hydrochloride capsules 0.4 mg should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole) [see Warnings and Precautions (5.2)]. If tamsulosin hydrochloride capsules administration is …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2026-01-01. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to tamsulosin, including drug-induced angio-oedema, or to any of the excipients
A history of orthostatic hypotension
Severe hepatic insufficiency

Side effects

Ejaculation disorders including retrograde ejaculation and ejaculation failure (common — abnormal ejaculation in approximately 2% of patients)
Dizziness (common, 1.3%); headache (uncommon); syncope (rare)
Orthostatic hypotension and palpitations (uncommon)
Nausea, vomiting, constipation, diarrhoea (uncommon); rhinitis (uncommon)
Rash, pruritus, urticaria (uncommon); angioedema (rare); Stevens-Johnson syndrome (very rare). Intraoperative Floppy Iris Syndrome has been associated with tamsulosin therapy during cataract and glaucoma surgery

Interactions

Strong CYP3A4 inhibitors — tamsulosin should not be given in combination with strong inhibitors of CYP3A4 in patients with a poor metaboliser CYP2D6 phenotype; use with caution in combination with strong and moderate CYP3A4 inhibitors
Cimetidine increases and furosemide lowers plasma levels of tamsulosin; as levels remain within the normal range, posology need not be changed
No interactions were seen when tamsulosin was given concomitantly with atenolol, enalapril or theophylline
US labelling (cross-check, not UK): should not be used in combination with other alpha-adrenergic blocking agents; caution with strong (e.g. paroxetine) or moderate (e.g. terbinafine) CYP2D6 inhibitors and in known CYP2D6 poor metabolisers, particularly above 0.4 mg; concomitant PDE5 inhibitors can potentially cause symptomatic hypotension; exercise caution with concomitant warfarin

Clinical monograph

How it works

It selectively blocks alpha-1A adrenoceptors in the prostate, prostatic capsule and bladder neck, relaxing smooth muscle there to improve urine flow.

Prescribing in practice

Warn patients and surgeons of intraoperative floppy iris syndrome — patients must tell the ophthalmologist they take, or have taken, tamsulosin before cataract or other eye surgery.
Postural hypotension and dizziness can occur, though less than with non-selective alpha-blockers.
Retrograde or abnormal ejaculation is a recognised effect.

Monitoring

Check lying and standing blood pressure, particularly early in treatment, and review symptom response; exclude prostate cancer before attributing symptoms to benign disease.

Counselling the patient

Before any eye surgery, including cataract surgery, tell the eye surgeon you take this medicine — even if you stopped it a while ago.
Stand up slowly at first, as you may feel dizzy or light-headed.
You may notice less or no fluid when you ejaculate; this is harmless.

Evidence & guidelines

An established option for moderate-to-severe BPH symptoms in NICE guidance; MHRA advice on intraoperative floppy iris syndrome.

Reference: NICE CG97; 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