Class Explorer · Genitourinary
Benign prostatic hyperplasia agents
Two mechanisms for one symptom set: relax the smooth muscle of the prostate and bladder neck now, or shrink the gland over months.
Members
TamsulosinRelaxes the prostate in days, and complicates cataract surgery for years.FinasterideShrinks the prostate over months, and halves the PSA while doing it.
Also in this class: Alfuzosin · Silodosin · Dutasteride. Full pages arrive as the library grows.
Compare the members
Tamsulosin
- Onset
- Days
- What it does
- Relaxes smooth muscle
Finasteride
- Onset
- 3 to 6 months
- What it does
- Shrinks the gland
Shared across the class
- Indications
- Benign prostatic hyperplasia with lower urinary tract symptoms
- Adverse effects
- Ejaculatory dysfunction · Dizziness (alpha blockers)
- Contraindications
- Pregnancy exposure (5-alpha reductase inhibitors: not to be handled by anyone who may become pregnant)
- Monitoring
- Symptom score · Blood pressure and orthostatic symptoms early · PSA, remembering that finasteride roughly halves it
What makes each agent different
- An alpha-1 blocker works within days and does nothing to the size of the prostate; a 5-alpha reductase inhibitor takes three to six months and only helps a genuinely enlarged gland.
- Tamsulosin is relatively uroselective, so it drops blood pressure less than the older non-selective alpha blockers, but first-dose dizziness is still real.
Intraoperative floppy iris syndrome complicates cataract surgery in patients on alpha blockers even years after stopping. The ophthalmologist must be told.
Finasteride halves PSA, so a measured value is doubled before interpretation. Forgetting that has delayed prostate cancer diagnoses.
Last reviewed 2026-08-16 · Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.