What Proscar Treats
Proscar (finasteride 5 mg) is FDA-approved to treat symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate. The medication works by shrinking the prostate gland, improving urinary symptoms, and reducing the risk of acute urinary retention and BPH-related surgery 1.
Primary Indication: Benign Prostatic Hyperplasia (BPH)
Proscar is specifically indicated for men who have both lower urinary tract symptoms (LUTS) AND demonstrable prostatic enlargement 2. This is a critical distinction—finasteride is ineffective and not appropriate for men with LUTS who do not have an enlarged prostate 2, 3.
Key Requirements for Treatment:
- Prostate volume >30cc or PSA >1.5 ng/mL for reliable response 4
- Presence of bothersome urinary symptoms
- The larger the prostate, the more pronounced the treatment effects 4
Clinical Benefits:
Symptom Improvement:
- Average 3-point improvement in AUA Symptom Index, which patients perceive as meaningful change 2, 3
- Slower onset than alpha-blockers—patients need counseling about gradual improvement over 6+ months 4
Anatomic Changes:
- 15-25% reduction in prostate volume at 6 months 4
- 19-24% decrease in prostate size maintained long-term 5, 6
- Increases peak urinary flow rate by approximately 1.6 mL/second 5
Disease Progression Prevention:
- Reduces risk of acute urinary retention by 67% 2
- Reduces need for BPH-related surgery by 64-67% 2
- Absolute benefit increases with rising prostate volume or serum PSA 2
Combination Therapy
Proscar may be prescribed in combination with an alpha-blocker (such as doxazosin) for men with LUTS and demonstrable prostatic enlargement 2, 1. Long-term data (5 years) shows combination therapy:
- Reduces overall risk of progression by 67% (vs 39% for alpha-blocker alone, 34% for finasteride alone) 2
- Reduces risk of acute urinary retention by 79% 2
- More effective than monotherapy for preventing symptom progression 2
Important Caveats and Warnings
PSA Monitoring:
- Finasteride reduces serum PSA by approximately 50% after 12 months 7, 4, 1
- After 1 year of therapy, measured PSA should be doubled to accurately gauge prostate cancer risk 7, 3
- The free/total PSA ratio remains constant and requires no adjustment 1
Prostate Cancer Risk:
- The FDA label warns of an increased risk of high-grade (Gleason 8-10) prostate cancer in men taking finasteride (1.8% vs 1.1% placebo in the PCPT trial) 1
- This finding remains controversial regarding whether it represents true increased risk or detection bias
- Men should continue regular prostate cancer screening while on Proscar 1
Sexual Side Effects:
- Decreased libido, erectile dysfunction, and ejaculatory disorders occur more frequently than placebo 2, 1
- These effects are "reversible and uncommon after the first year of therapy" according to guidelines 2, 3
- Decreased ejaculate volume (approximately 0.6 mL or 22%) is common but doesn't interfere with sexual function 1
Contraindications:
- Absolutely contraindicated in women who are or may become pregnant 1
- Pregnant women must not handle crushed or broken tablets due to risk of male fetal genital abnormalities 1
Not Indicated For
Proscar is NOT indicated for: