Oral Medication for Male Androgenetic Alopecia
Prescribe oral finasteride 1 mg daily as the first-line oral medication for adult males with androgenetic alopecia, after obtaining baseline liver function tests and PSA levels. 1, 2
Finasteride: The Evidence-Based Choice
Finasteride 1 mg daily is the FDA-approved oral medication specifically indicated for male pattern hair loss and represents the optimal dose established through dose-ranging clinical trials. 1, 3 This type 2 5α-reductase inhibitor blocks conversion of testosterone to dihydrotestosterone (DHT), the androgen directly responsible for pattern baldness in genetically predisposed men. 3
Efficacy Data
83% of men taking finasteride 1 mg daily had no further hair loss at 2 years compared to only 28% of placebo recipients, demonstrating robust prevention of progression. 3
66% of finasteride-treated men showed improvement in hair growth at 2 years versus 7% with placebo, based on global photographic assessment. 3
Long-term data over 5 years demonstrates durable improvements in scalp hair growth with continued treatment, while placebo recipients experienced progressive hair loss. 2, 4
Hair count improvements demonstrated at 1 year are maintained throughout 5 years of continuous therapy. 2, 4
Critical Baseline Testing Requirements
Before prescribing finasteride, you must obtain baseline PSA levels because finasteride decreases PSA by approximately 50% after 12 months of therapy. 5 This PSA suppression effect is clinically significant even at the 1 mg dose used for hair loss—not just the 5 mg dose used for benign prostatic hyperplasia. 5
Apply a multiplier of 2 to PSA values after 12 months of finasteride therapy when interpreting results for prostate cancer screening. 5
The PSA decline at 3 years may exceed 50%, requiring adjustment of the multiplier to 2.3 in some patients. 5
No uniformly validated PSA cut-point exists for men taking 5α-reductase inhibitors due to inter-individual variability, so clinical judgment is essential. 5
Baseline liver panel testing is prudent given the hepatic metabolism of finasteride, though significant hepatotoxicity has not been identified in clinical trials. 1, 2
Safety Profile and Sexual Adverse Effects
The overall incidence of treatment-related adverse events with finasteride 1 mg daily (7.7%) is nearly identical to placebo (7.0%). 3 However, sexual function disorders occur more frequently with finasteride (3.8%) versus placebo (2.1%), including decreased libido, ejaculation disorders, and erectile dysfunction. 3
Importantly, sexual adverse effects typically resolve in two ways: 3
- All sexual adverse events reversed upon discontinuation of therapy
- Many resolved spontaneously in patients who continued treatment
In the long-term Prostate Cancer Prevention Trial examining finasteride 5 mg (higher dose than used for hair loss), sexual dysfunction associated with finasteride decreased over time, with a mean effect size of only 3.21 points on a 0-100 scale—smaller than natural age-related variability. 5
Treatment Duration and Expectations
Finasteride must be continued indefinitely to maintain benefits, as discontinuation leads to reversal of hair growth within months—similar to all hair loss treatments. 6, 7 The planned treatment duration in the pivotal Prostate Cancer Prevention Trial was 7 years, establishing precedent for long-term safety. 5
Alternative Oral Option (When Finasteride is Not Suitable)
If finasteride is contraindicated or not tolerated, low-dose oral minoxidil 1 mg daily represents an alternative oral medication, though evidence suggests slightly lower efficacy than topical formulations and it is not FDA-approved for this indication. 7 Oral minoxidil carries risk of hypertrichosis, dizziness, and lower limb edema. 8
Dutasteride: A More Potent Alternative
While not FDA-approved for androgenetic alopecia, dutasteride 0.5 mg daily has been proven to induce better responses than finasteride, especially in the frontal area, as it inhibits both type 1 and type 2 isoforms of 5α-reductase. 8 However, the amount of PSA suppression with long-term dutasteride has not been well-characterized, making monitoring more challenging. 5
Critical Pitfalls to Avoid
Failing to obtain baseline PSA before starting finasteride eliminates your ability to properly interpret future PSA values for prostate cancer screening. 5
Not counseling patients about the 50% PSA reduction effect can lead to missed prostate cancer diagnoses or unnecessary biopsies. 5
Discontinuing treatment prematurely (before 12 months) prevents assessment of full efficacy, as maximal response typically requires 6-12 months. 6, 2
Not distinguishing androgenetic alopecia from alopecia areata is essential—this recommendation applies only to pattern hair loss, not patchy autoimmune hair loss which requires different treatment. 6, 7