Tamsulosin !
An alpha-1A blocker that relaxes the prostate and bladder neck so urine flows more easily in benign prostatic hyperplasia. It is not used for hypertension.
Updated 2026-11-01
The figure shows tamsulosin bound to the human alpha-1A adrenergic receptor (cryo-EM structure with a nanobody).
Mechanism of action
Tamsulosin blocks alpha-1A (and alpha-1D) receptors more than the alpha-1B subtype. Alpha-1A receptors predominate in the smooth muscle of the prostate, prostatic capsule and bladder neck; relaxing it reduces the dynamic obstruction to urine flow. Its smaller effect on vascular receptors means less fall in blood pressure than with other alpha-1 blockers.
- Tamsulosin blocks alpha-1A receptors in the prostate and bladder neck
- Prostatic smooth muscle relaxes
- Urine flows more easily; blood pressure changes little
Pharmacokinetics
- Absorption
- Oral, as modified-release capsules; well absorbed
- Metabolism
- Liver, by CYP3A4 and CYP2D6
- Elimination
- Metabolites conjugated and excreted in urine
- Half-life
- About 9 to 13 hours in healthy volunteers and 14 to 15 hours in the target population (label)
Indications
- Signs and symptoms of benign prostatic hyperplasia Benign prostatic hyperplasia →
- Other uses: kidney stones Kidney stones (urolithiasis) →
Adverse effects
Common
- Dizziness on standing
- Abnormal ejaculation (reduced, absent or retrograde)
- Runny or stuffy nose
- Sleepiness or trouble sleeping
- Weakness and back pain
Contraindications
- Hypersensitivity to tamsulosin or any component
Key interactions
- Strong CYP3A4 inhibitors (for example ketoconazole)
- Much higher tamsulosin levels: the combination is avoided
- CYP2D6 inhibitors (for example paroxetine) and moderate CYP3A4 inhibitors
- Higher levels; used with caution
- PDE-5 inhibitors
- Additive fall in blood pressure
What is monitored
- Urinary symptoms and flow
- Blood pressure lying and standing
- Prostate cancer is excluded before and periodically during treatment
Nursing care
- Warn about dizziness and fainting, especially at the start or when treatment restarts after a break.
- Before cataract or glaucoma surgery, tell the eye surgeon about tamsulosin use.
- An erection lasting several hours is an emergency.
- Ask about sulfa allergy before the first dose.
Pregnancy and breastfeeding
Tamsulosin is not indicated for women.
Test yourself
Think of the answer, then tap the question to see it.
Why does tamsulosin lower blood pressure less than prazosin?
It has higher affinity for alpha-1A receptors, which predominate in prostatic smooth muscle, than for the vascular subtypes.
What should a patient on tamsulosin tell the eye surgeon before cataract surgery?
That they take an alpha-1 blocker, because of the risk of intraoperative floppy iris syndrome.
Which antifungal must not be combined with tamsulosin, and why?
Ketoconazole, a strong CYP3A4 inhibitor, which greatly raises tamsulosin levels.
Which ejaculatory problem is typical of tamsulosin?
Abnormal ejaculation: reduced, absent or retrograde ejaculation.
Related drugs
Related conditions
← Back to the class: Alpha blockers
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - TAMSULOSIN HYDROCHLORIDE capsule (DailyMed (U.S. National Library of Medicine), 2026); Tamsulosin: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Farmacología básica y clínica (Katzung), cap. 10 (McGraw Hill, 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.