What is the duration for finasteride (generic name for Propecia) to take effect in treating androgenetic alopecia (hair loss)?

From the Guidelines

Finasteride typically takes 3 to 6 months to show noticeable results for hair loss, with maximum benefits often seen after 1 to 2 years of consistent use. The provided evidence does not directly address the duration for finasteride to take effect in treating androgenetic alopecia, as it focuses on the use of finasteride for central serous chorioretinopathy 1. However, based on the general understanding of finasteride's mechanism of action, it is known to work by blocking the conversion of testosterone to dihydrotestosterone (DHT), which is responsible for shrinking hair follicles. Key points to consider when using finasteride for hair loss include:

• The standard dosage for male pattern baldness is 1 mg daily, taken orally
• Patience is essential as the medication works gradually
• Some users may experience a temporary increase in shedding known as "initial shed," which is actually a sign the medication is working as new hair cycles begin
• For optimal results, continue taking finasteride daily without interruption, as stopping treatment will cause DHT levels to rise again and hair loss to resume within 6-12 months
• Regular follow-up photographs every 3-6 months can help track progress
• Side effects are uncommon but may include reduced libido, erectile dysfunction, or decreased ejaculate volume in a small percentage of men, although the provided evidence does not discuss these side effects in the context of hair loss treatment 1.

From the Research

Duration of Finasteride Treatment for Androgenetic Alopecia

The duration for finasteride to take effect in treating androgenetic alopecia can vary, but several studies provide insight into its efficacy over time.

• Finasteride has been shown to promote hair growth and prevent further hair loss in a significant proportion of men with male pattern hair loss, with improvements in hair count reported after 1 year and maintained during 2 years' treatment 2.
• In men with vertex hair loss, global photographs showed improvement in hair growth in 48% of finasteride recipients at 1 year and in 66% at 2 years compared with 7% of placebo recipients at each time point 2.
• Long-term studies have demonstrated the efficacy and safety of finasteride over five years, with durable improvements in scalp hair growth and slowing of the further progression of hair loss that occurred without treatment 3.
• Finasteride 1 mg/day has been shown to significantly increase total hair count compared to placebo after 24 weeks and 48 weeks, with a mean difference of 12.4 hairs/cm2 and 16.4 hairs/cm2, respectively 4.

Time to Visible Effects

• Visible hair growth can be produced in up to 66% of men with mild to moderate alopecia, and finasteride can stop hair loss in 91% of patients 5.
• The proven preservative effect of finasteride, in addition to its restorative effect, is a strong indication for prescribing it in early cases of androgenetic alopecia before much hair has been lost 5.
• Finasteride can lead to durable improvements in scalp hair over five years, while treatment with placebo leads to progressive hair loss 3.

Overall Efficacy and Safety

• Finasteride is generally well-tolerated, with the most common adverse events including reduced libido, decreased ejaculate volume, and gynaecomastia 6, 4.
• The overall incidence of sexual function disorders, comprising decreased libido, ejaculation disorder, and erectile dysfunction, was significantly greater in finasteride than placebo recipients 2, 4.