eMedExpert Home > Medications Facts > Finasteride (Propecia)

Finasteride (Propecia) is a specific type II 5-alpha reductase inhibitor. It inhibits the enzyme responsible for regulating conversion of testosterone to dihydrotestosterone (DHT). By reducing DHT levels in the scalp, the drug decreases DHT's effects on the hair follicles, reversing the process of hair loss.

Finasteride significantly reduces hair loss progression and restores hair growth in men with male pattern hair loss.

Finasteride was originally developed by Merck to treat BPH (benign prostatic hyperplasia) or an enlarged prostate. It was subsequently discovered that people who were taking Proscar (finasteride) were experiencing hair regrowth.

Merck & Co started clinical testing in the early 90s to evaluate the effectiveness of finasteride in treating hair loss. To minimize the potential of side effects that come with Proscar (5 mg finasteride), Merck & Co. conducted clinical testing on 1 mg finasteride as a treatment for hair loss.

On December 22, 1997 the FDA approved a 1 mg dose of finasteride for the treatment of androgenic alopecia in men.

• Treatment of male pattern hair loss (androgenic alopecia) in men only.
• Treatment of symptomatic benign prostatic hyperplasia (BPH) in men with enlarged prostate; in combination with doxazosin to reduce the risk of symptomatic progression of BPH.

• Hirsutism in women1
• Hair transplant4
  Finasteride improves scalp hair and growth of nontransplanted hair in areas surrounding the transplant.

Because male pattern hair loss is essentially a cosmetic problem, it is important to be fully informed of both the "pros" and "cons" of finasteride before treatment decisions are made.

Advantages:

• Effective: increases hair growth and prevents further hair loss. The vast majority of men using finasteride (Propecia) experience some benefit from its use2. Men with mild to moderate, but not complete, hair loss can expect to benefit from the use of this drug.
  The success rate of Propecia in the improvement of hair growth varies from 58 to 66%6-8.
  The success rate in the prevention of further hair loss is up to 83%7.
• Lack of drug interactions. Finasteride has not been shown to interfere with other medicines.
• Suitable for long-term treatment. Follow-up studies have reported that the drug is safe and effective over the long-term5. No major side effects have been seen with finasteride 1 mg for up to 5 years.
• Good tolerability.

Disadvantages:

• Not a cure for hair loss. Unfortunately, Propecia does not 'cure' male pattern hair loss. Any benefits are lost when medication is stopped. It will only work over the long term if you continue taking it. If you stop taking Propecia, you will likely lose any hair you have gained within 12 months of stopping treatment.
• Not suitable for women. Finasteride has not been proven to be effective in postmenopausal women3. Because of the risk of finasteride causing malformation in male fetuses, clinical trials of this drug as a treatment for women androgenetic alopecia were originally restricted to post menopausal women.
• Sexual side effects, such as difficulty in achieving an erection, less desire for sex, decreased amount of semen released during sex (this decrease does not appear to interfere with normal sexual function). These side effects are reversible after discontinuation of the medication.
  Sexual side effects from finasteride are most prominent in first year.
• Expensive.

Male pattern hair loss, or androgenetic alopecia, is an androgen-dependent disorder. In genetically susceptible men, dihydrotestosterone (DHT), a potent metabolite of the male androgen testosterone, contributes to male pattern hair loss.

The conversion of testosterone to DHT is regulated by the enzyme 5-alpha reductase. Finasteride inhibits this enzyme. By reducing DHT levels in the scalp, the drug decreases DHT's harmful effects on the hair follicles, reversing the process of hair loss.

Finasteride decreases DHT concentrations in the serum and the scalp by up to 70 and 60%, respectively.

Finasteride does not affect hair on other parts of the body.

Male pattern hair loss is a condition that develops over a long period of time. Because it takes time for new hair to grow, you will not see immediate results. In general, daily use for 3 months or more may be necessary before you notice increased hair growth or prevention of further loss.

If you stop taking Finasteride
If you stop taking the tablets, DHT levels will rise again in the scalp, and your hair loss is likely to resume.

Finasteride half-life is 6 hours (range 3-16).

• Finasteride (Propecia) versus Other Medications

• 1. Wong IL, Morris RS, Chang L, Spahn MA, Stanczyk FZ, Lobo RA. Free Full Text A prospective randomized trial comparing finasteride to spironolactone in the treatment of hirsute women. J Clin Endocrinol Metab. 1995 Jan;80(1):233-8.
• 2. Kaufman KD, Olsen EA, Whiting D, Savin R, DeVillez R, Bergfeld W, Price VH, Van Neste D, Roberts JL, Hordinsky M, Shapiro J, Binkowitz B, Gormley GJ. Abstract Finasteride in the treatment of men with androgenetic alopecia. Finasteride Male Pattern Hair Loss Study Group. J Am Acad Dermatol. 1998 Oct;39(4 Pt 1):578-89. PubMed
• 3. Price VH, Roberts JL, Hordinsky M, Olsen EA, Savin R, Bergfeld W, Fiedler V, Lucky A, Whiting DA, Pappas F, Culbertson J, Kotey P, Meehan A, Waldstreicher J. Lack of efficacy of finasteride in postmenopausal women with androgenetic alopecia. J Am Acad Dermatol. 2000 Nov;43(5 Pt 1):768-76. PubMed
• 4. Leavitt M, Perez-Meza D, Rao NA, Barusco M, Kaufman KD, Ziering C. Effects of finasteride (1 mg) on hair transplant. Dermatol Surg. 2005 Oct;31(10):1268-76, discussion 1276.
• 5. Price VH, Menefee E, Sanchez M, Kaufman KD. Changes in hair weight in men with androgenetic alopecia after treatment with finasteride (1 mg daily): three- and 4-year results. J Am Acad Dermatol. 2006 Jul;55(1):71-4. Epub 2006 May 3. PubMed
• 6. Kawashima M, Hayashi N, Igarashi A, Kitahara H, Maeguchi M, Mizuno A, Murata Y, Nogita T, Toda K, Tsuboi R, Ueki R, Yamada M, Yamazaki M, Matsuda T, Natsumeda Y, Takahashi K, Harada S. Finasteride in the treatment of Japanese men with male pattern hair loss. Eur J Dermatol. 2004 Jul-Aug;14(4):247-54. PubMed
• 7. McClellan KJ, Markham A. Abstract Finasteride: a review of its use in male pattern hair loss. Drugs. 1999 Jan;57(1):111-26. PubMed
• 8. Lin JH, Chen WC. Finasteride in the treatment of Taiwanese men with androgenetic alopecia: a 12-month open-label study. Kaohsiung J Med Sci. 2002 Aug;18(8):379-85. PubMed