Drug reference

Tamsulosin

Alpha Blocker · Drug for Benign Prostatic Hyperplasia (BPH)

Also known as Tamsulosin Hydrochloride

START

Confirm BPH diagnosis (DRE, PSA, symptom score). Assess fall risk. Counsel on first-dose syncope — take at bedtime. Rule out prostate cancer (elevated PSA). Start 0.4 mg daily.

TYPICAL MAX

0.8 mg/day. No additional benefit beyond 0.8 mg; increased side effects.

STOP IF

Syncope, severe orthostatic hypotension, priapism, severe allergic reaction, cataract surgery planned (discontinue before IFIS risk)

WATCH

Orthostatic BP (sitting and standing), dizziness, ejaculatory function, IPSS score, PSA (does not affect PSA levels), eye surgery planning (IFIS warning)

CDSCO approvedSchedule HJan AushadhiATC G04CA02

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 1.1h · absorption onset
PEAK: 4.5h · 4-5 h (modified-release)
t½: 14h · 9-15 h (mean 14 h)
DURATION: 1d · 24 h (once-daily dosing)

EXCRETION

~76% fecal (metabolites); ~21% renal; hepatic CYP3A4/CYP2D6

route + CYP

INTERACTIONS

12 major

SEVERE in our sources

PREGNANCY

FDA PLLR: Not indicated for use in women. If used in pregnant women (rare), no adequate data. Alpha-blockade could theoretically affect uterine contractility.

FDA category + note

Top interactionssee all 12 →

AmprenavirSevereDatabaseDDInter
AtazanavirSevereDatabaseDDInter
BoceprevirSevereDatabaseDDInter
CeritinibSevereDatabaseDDInter

Available in India

174 branded formulations and 246 fixed-dose combinations. Look up specific brands in the Drugs workspace.

Jan Aushadhi — generic available at GoI pharmacies

Mechanism

Tamsulosin is a selective alpha-1 adrenergic receptor antagonist with particular affinity for the alpha-1A subtype, which is predominantly expressed in the prostate smooth muscle, prostatic urethra, bladder neck, and seminal vesicles. By blocking alpha-1A receptors, tamsulosin relaxes smooth muscle in the prostate and bladder neck, reducing urethral resistance and improving urinary flow in patients with benign prostatic hyperplasia (BPH). Unlike non-selective alpha-blockers (prazosin, terazosin), tamsulosin has minimal effect on alpha-1B receptors in vascular smooth muscle, resulting in less orthostatic hypotension. It has no effect on 5-alpha-reductase and does not reduce prostate size.

Indications

Benign prostatic hyperplasia (BPH) — treatment of signs and symptomsLower urinary tract symptoms (LUTS) due to BPHUreteral stone expulsion (off-label — facilitates passage of distal ureteral stones)Chronic prostatitis/chronic pelvic pain syndrome (off-label)

Dosing

Adult: BPH: 0.4 mg PO once daily, 30 minutes after the same meal each day. If inadequate response after 2-4 weeks: increase to 0.8 mg once daily. Ureteral stones: 0.4 mg PO daily (off-label).
Pediatric: Not recommended <18 years.
Renal adjustment: No dosage adjustment required in renal impairment (mild–severe); not studied in ESRD (FDA §8.6).
Hepatic adjustment: No adjustment for mild–moderate hepatic impairment; not studied in severe hepatic impairment — use caution (FDA §8.7; not contraindicated).
Geriatric: Start 0.4 mg daily; monitor for orthostatic hypotension and falls. First-dose effect — take at bedtime to minimize syncope risk.
Max dose: 0.8 mg/day

Pharmacokinetics

Onset

Symptom improvement within 1-2 weeks; maximum effect at 4-6 weeks.

Peak effect

Oral: peak plasma at 4-5 hours (modified-release). Food increases Cmax by ~30% and reduces variability.

Duration

24 hours (supports once-daily dosing).

Half-life

~9-15 hours (mean 14-15 hours in healthy volunteers; 22 hours in elderly).

Bioavailability

~90% (oral modified-release formulation).

Protein binding

~98-99% (bound to human serum albumin and alpha-1-acid glycoprotein).

Metabolism

Extensive hepatic via CYP3A4 (primary) and CYP2D6 (secondary). No active metabolites.

Excretion

Feces: ~76% (as metabolites via biliary excretion). Urine: ~21% (as metabolites). <10% excreted unchanged.

Contraindications

Hypersensitivity to tamsulosin, silodosin, or other alpha-blockers
Concurrent use with strong CYP3A4 inhibitors (increases levels and hypotension risk)
History of orthostatic hypotension or syncope with alpha-blockers

Side effects

Common

Dizziness, lightheadednessOrthostatic hypotension (first-dose effect)HeadacheAbnormal ejaculation (retrograde ejaculation, decreased semen volume — dose-related, ~18% at 0.8 mg)Rhinitis, nasal congestionSomnolence, fatigueBack pain

Serious

Syncope (first-dose effect, dose-related; risk increased with concurrent antihypertensives)
Intraoperative floppy iris syndrome (IFIS — during cataract surgery; alpha-1 blockade affects iris dilator muscle; can occur even after discontinuation)
Priapism (rare)
Severe hypersensitivity (SJS, TEN, angioedema, anaphylaxis — rare)
Jaundice, hepatic dysfunction

Pregnancy & lactation

Pregnancy

FDA PLLR: Not indicated for use in women. If used in pregnant women (rare), no adequate data. Alpha-blockade could theoretically affect uterine contractility.

Lactation

Not indicated for women. If excreted in breast milk, effects unknown.