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Frequently Asked Questions about Dutasteride

  1. What is Dutasteride?

  2. What is DHT?

  3. How does Dutasteride work and how is it different than Propecia (Finasteride)?

  4. Is Dutasteride better than Propecia for hair growth?

  5. Does Dutasteride have any side effects?

  6. Are there more risks with Dutasteride than Finasteride?


1. What is Dutasteride?

Dutasteride is FDA approved for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men, similar to Finasteride 5mg (Proscar®). However, only Finasteride 1mg (Propecia®) is FDA approved for the treatment of male pattern hair loss (androgenetic alopecia), where Dutasteride is not. The studies on Dutasteride and hair growth have been stopped. The medical community has not been told why the company stopped the hair growth studies or if they will be completed sometime in the future.

Theoretically, Dutasteride should work similar to Finasteride in improving, stabilizing and treating male pattern hair loss. Dutasteride is an oral medication that you take once a day, with or without food, with or without medication, morning or night - it doesn't matter. Dutasteride is available only by prescription. Dutasteride is for use by men ONLY and should NOT be used by women or children.

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2. What is DHT?

DHT (DiHydroTestosterone) is one of many male hormones in the body. DHT is important early in the development of a male fetus; however, as an adult it appears to cause:

  • Prostate Enlargement

  • Acne

  • Male Pattern Hair Loss

  • Hair Growth (Unfortunately in the ears, nose, and back.)

Most men do not want to deal with the above problems.

DHT is believed to contribute to male pattern baldness by:

  • Shortening of the growth phase of the hair follicle.

  • Progressive miniaturization of hair follicles.

  • Decreasing number of visible hairs.

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3. How does Dutasteride work and how is it different from Propecia®?

Dutasteride is chemically similar to Finasteride, the active compound in Propecia®. It inhibits the conversion of testosterone into DHT by blocking the enzyme, 5-alpha reductase. There are 2 forms of 5-alpha reductase, type 1 and type 2. Dutasteride blocks both of these isoenzymes, where Finasteride blocks mainly the type 2 isoenzyme.

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4. Is Dutasteride better than Propecia® for hair growth?

The answer is we do not know. There are no studies on Dutasteride to compare to the Finasteride studies looking at hair count or hair weight at 1 year, 2 year, 3 year, or 5 years.

GlaxoSmithKline only completed Phase II hair growth studies on Dutasteride. This was a short six month study of hair growth in men taking Dutasteride 0.5 mg a day. It did show increased hair counts. The hair counts measured in a 1 inch diameter circle increased by an average 96 hairs with 0.5mg Dutasteride.

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5. Does Dutasteride have any side effects?

Clinical trials showed that it was generally well tolerated. Most side effects were mild, and generally went away while on treatment in both the Dutasteride and placebo groups.

Drug-related side effects during the first six months were as follows:

  • Impotence (4.7% vs. 1.7% for placebo)

  • Decreased Libido (3% vs. 1.4% for placebo)

  • Breast Tenderness and Breast Enlargement (gynecomastia; 0.5% vs. 0.2% with placebo)

  • Ejaculation Disorders (1.4% vs. 0.5% with placebo)

Dutasteride should not be used in women and children. Women who are pregnant or may become pregnant should not handle this medicine because of possibility of absorption and subsequent potential risk to a male fetus.

Men treated with Dutasteride should not donate blood until at least six months after their final dose to prevent the medicine going to a pregnant woman through a blood transfusion.

Men with liver disease should talk to their doctor before taking Dutasteride.

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6. Are there more risks with Dutasteride than Finasteride?

The answer is possibly. Finasteride only blocks the type 2 isoenzyme of 5-alpha reductase, where Dutasteride blocks both the type 1 and type 2 isoenzymes of 5-alpha reductase.

There is a genetic model of patients without type 2-5 alpha reductase. There is a small group of the human population that has a genetic defect which causes them not to produce type 2 5-alpha reductase. These people live healthy lives without any increased disease risk (In matter of fact, they do not experience male pattern hair loss, their prostates do not enlarge, and they do not develop prostate cancer). Furthermore, Finasteride has been taken by humans going on 20 years without seeing any long term side effects. Therefore, the medical community feels very comfortable blocking type 2 5-alpha reductase, which again is what Propecia® does.

There is no genetic model of humans not having type 1 5-alpha reductase. There are type 1 5-alpha reductase receptors throughout the body, including the brain. The medical community does not know the implications to long term suppression of type 1 5-alpha reductase. Therefore the medical community does not know if there are long term implications to suppressing type 1 5-alpha reductase, which Dutasteride blocks.


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