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Propecia, the Baldness Pill: Does it Work?

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How Does Finasteride Work? | The Good News and the Bad News | Side Effects

If you are a man with hereditary hair loss, there are products available to help you keep your hair. One option is finasteride (Propecia), a prescription medicine that is in tablet form and taken orally.

How Does Finasteride Work?

Finasteride was first developed to shrink enlarged prostate glands. Researchers noticed that it also helped grow hair, so a special lower-dose formulation—Propecia—was developed for hair loss.

Finasteride interferes with conversion of testosterone to another hormone called 5 alpha-dihydro-testosterone (or DHT). DHT reduces hair follicle activity. Over time and under the influence of DHT, follicles sprout thinner hairs until no hair regrows. When finasteride blocks DHT production, thinning of hair ceases and a more normal growth may possibly occur.

The Good News and the Bad News

A review of multiple trials including thousands of men and lasting up to two years found that taking finasteride was associated with improved hair growth and increased hair count, but that is also associated with erectile dysfunction and other sexual problems.

But, it is not only finasteride's ability to grow hair that interests some doctors. Finasteride may help men to stop losing the hair they have. So it appears that even if finasteride does not help you grow lots of new hair, it is a good bet you will keep what you have—at least for a while.

You must be patient, though, and be willing to take the drug once a day indefinitely. It may take 3-4 months before new hair is noticed. If you stop taking the drug, all of your newly grown hair will fall within a year. Also, taking the medicine every day can be expensive.

Side Effects

Finasteride has some potentially unsettling side effects. The medicine has been associated with a reduced sex drive, problems with ejaculation, and orgasm disorders that continue even after you stop taking the drug. Male infertility and poor semen quality are also possible with finasteride, but these problems should improve after you stop taking the drug.

If you are taking the medicine, be sure that your doctors knows. One effect of taking finasteride is that it will lower PSA, a compound produced by the body in the presence of a prostate cancer or just with increased age. Blood tests checking for PSA levels may be more difficult to interpret as a result of the medicine being in your system. If you have both hair loss and symptoms of prostate enlargement (eg, hesitancy in urinating, diminished urinary stream), you may find that these symptoms improve because the medicine is also used to treat benign prostatic hypertrophy.

If you have hereditary hair loss, there are treatment options available. Talk to your doctor about whether you are a good candidate to take finasteride. There are other options available, as well, like hair transplant surgery and the over-the-counter product minoxidil (Rogaine).


American Academy of Dermatology


American Hair Loss Council



Canadian Dermatology Association



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Shapiro J, Kaufman KD. Use of finasteride in the treatment of men with androgenetic alopecia (male pattern hair loss). J Investig Dermatol Symp Proc. 2003;8(1):20-23.

Last reviewed July 2012 by Brian Randall, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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