Finasteride for Male Pattern Hair Loss
Finasteride 1 mg daily is the recommended medical treatment for male pattern hair loss in men aged 18-60 years, with visible improvement typically beginning by 12 weeks and maximal benefit at 1-2 years. 1
Dosing and Administration
- Prescribe finasteride 1 mg once daily for male pattern hair loss, as recommended by the American Academy of Dermatology 1
- The 1 mg dose produces similar DHT suppression (approximately 50%) as the 5 mg dose used for benign prostatic hyperplasia 2
- Treatment must be continued long-term, as efficacy is maintained over 5+ years but hair loss resumes if discontinued 1, 2
Expected Efficacy
- 58% of men show improvement at 48 weeks based on global photographic assessment 3
- At 2 years, 66% of men demonstrate improvement in hair growth compared to 7% with placebo 4
- Hair counts show that 83% of finasteride-treated men have no further hair loss at 2 years versus 28% with placebo 4
- Long-term data demonstrates durable improvements maintained over 5 years 5
Critical PSA Monitoring Requirement
Men taking finasteride 1 mg must have their PSA values doubled after 12 months of therapy when screening for prostate cancer, as finasteride reduces PSA levels by approximately 50% after 12 months 1, 2, 6
- This adjustment applies equally to the 1 mg dose (for hair loss) and the 5 mg dose (for BPH) 2, 6
- Consider obtaining a baseline PSA before starting treatment in men approaching prostate cancer screening age (>40-45 years) 1
- The median PSA decrease is 40% in men aged 40-49 years and 50% in men aged 50-60 years after 48 weeks 6
Sexual Side Effects Profile
- Sexual dysfunction occurs in approximately 2-4% more patients compared to placebo 1
- Specific adverse events include decreased libido, ejaculation disorders, and erectile dysfunction 1, 4
- The overall incidence of sexual function disorders (3.8% vs 2.1% placebo) is not dramatically different from placebo, with a mean difference of 3.21 points on sexual function scales compared to 1.26 points for each year of aging 1
- Sexual adverse events are reversible upon discontinuation and many resolve even with continued therapy 4
- These side effects are uncommon after the first year of therapy 7
Combination Therapy Option
When monotherapy is insufficient, combining finasteride 1 mg with minoxidil achieves superior results through complementary mechanisms—finasteride blocks DHT conversion while minoxidil promotes follicular growth through vasodilation 1
- No drug-drug interactions exist between these medications 1
- This combination is recommended as background therapy in treatment protocols for androgenetic alopecia 1
- When using oral minoxidil, monitor for hypotension, tachycardia, fluid retention, and hypertrichosis 1
Patient Counseling Points
- Set realistic expectations: visible improvement begins at 12 weeks, with maximal benefit at 1-2 years 1
- Emphasize that this is a long-term treatment commitment, as discontinuation results in resumption of hair loss 1, 2
- Discuss the small but real risk of sexual side effects (approximately 2-4% above placebo) 1
- Inform patients about PSA reduction and its implications for prostate cancer screening 1, 2
Common Pitfall to Avoid
The evidence provided focuses on BPH treatment, where finasteride is ineffective in patients without prostatic enlargement 7. This consideration does not apply to male pattern hair loss treatment, where the mechanism involves DHT inhibition at the hair follicle level rather than prostate volume reduction.