Finasteride in Brief
- Generic name : Finasteride
- Brand names: Propecia® , Proscar®
- Therapeutic class: Hair regrowth stimulant
- Pharmacologic class: Type II 5-alpha reductase inhibitor
- FDA Approved: December 22, 1997
- Pregnancy Category: X (contraindicated in pregnant women)
- Originally discovered: 1990s, Merck & Co, USA
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, finasteride 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 were experiencing
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 Propecia (finasteride 1 mg) for
the treatment of androgenic alopecia in men.
FDA approved uses
- Treatment of male pattern hair loss (androgenic alopecia) in men
- 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.
Off-label & Investigational uses
- Hirsutism in women1
- Hair transplant4
Finasteride improves scalp hair and growth of nontransplanted hair
in areas surrounding the transplant.
Finasteride "pros" and "cons"
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.
- Effective: increases hair growth and prevents further hair loss.
The vast majority of men using finasteride experience some
benefit from its use2. Men
with mild to moderate, but not complete, hair loss can
expect a favorable outcome.
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 it 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.
- Not a cure for hair loss. Unfortunately, Propecia does
not 'cure' male pattern hair loss. Any benefits are lost when the medication
is stopped. It will only work over the long term if you continue taking
it. If you stop, 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 tests in 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
Sexual side effects are most prominent in first year.
Mode of action
Finasteride is the 5alpha-reductase inhibitor. The 5alpha-reductase is an enzyme that catalyzes the conversion of testosterone to dihydrostestosterone (DHT), progesterone to dihydroprogesterone and deoxycorticosterone to dihydrodeoxycorticosterone.
Male pattern hair loss, or androgenetic alopecia, is an androgen-dependent
disorder. In genetically susceptible men, dihydrotestosterone,
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, thereby reducing DHT levels
in the scalp and 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 stimulate hair growth on other parts of the body.
How long does it take for Propecia for hair regrow?
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
If you stop taking Finasteride, DHT levels will rise again in the scalp,
and your hair loss is likely to resume.
Time to clear out the system
Finasteride half-life is 6 hours (range 3-16).
- 1. Lakryc EM1, Motta EL, Soares JM Jr, Haidar MA, de Lima GR, Baracat EC. The benefits of finasteride for hirsute women with polycystic ovary syndrome or idiopathic hirsutism. Gynecol Endocrinol. 2003 Feb;17(1):57-63. PubMed
- 2. Kaufman KD, Olsen EA, Whiting D, Savin R,
DeVillez R, Bergfeld W, Van Neste D, Roberts JL, Hordinsky
M, Shapiro J, Binkowitz B, Gormley GJ. Finasteride in the
treatment of men with androgenetic alopecia. J Am Acad Dermatol. 1998 Oct;39(4 Pt 1):578-89.
- 3.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.
- 5. 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.
- 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. Finasteride:
a review of its use in male pattern hair loss. Drugs. 1999 Jan;57(1):111-26.
- 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
Published: November 03, 2008
Last updated: June 18, 2014
- Propecia remains the first and only FDA-approved oral medication for hair loss.
- At the end of 2004 the World Anti-Doping Agency added finasteride
to its list of banned agents in international sports. The agency
calls finasteride a masking agent that hides the use of more nefarious
drugs like the steroid nandrolone.
- Finasteride 2.5 mg daily combined with an oral contraceptive
containing drospirenone and ethinyl estradiol (e.g. Yasmin, Yaz) may improve Female Pattern Hair Loss
at 1 year.