A: Finasteride, the active drug in Propecia, can change the quality of the semen, since it is decreasing the component of seminal fluid that is secreted by the prostate.

You may want to consider having your sperm counts checked, although a decreased sperm count is rare with finasteride. If the symptoms are not bothering you and the sperm counts are normal, it should be OK to continue the medication.

A: I am currently not recommending that patients take Dutasteride for hair loss, although it is more effective than Propecia, finasteride 1mg. (Dutasteride 0.5, the dose generally used for hair loss, seems to be slightly more effective than finasteride 5m in reversing miniaturization.)

The reasons that I am hesitant to prescribe it at present are outlined in the Hair Transplant Blog question Is Avodart Safe?

In addition to the reasons that I listed in that response, I would also consider that: Dutasteride, unlike finasteride, decreases sperm counts, it can result in persistent decreased sex drive and the incidence is greater than with finasteride. Finally there are a significant number of alpha-type 1 receptors in brain, those affected by dutasteride, but not finasteride.

However, since Dutasteride is approved for older men with prostatic disease, using it for hair loss in this age group (usually in a lower dose) is reasonable.

A: Yes, on both accounts. Alternate day therapy may decrease the side effects and still be effective in treating hair loss. The sexual side effects usually take a week or two to disappear after stopping the medication.

A: Avodart (dutasteride 0.5mg) was approved by the FDA for the treatment of prostate enlargement in men in 2002. Avodart has not been approved for the treatment of androgenetic hair loss, although physicians can use an approved medication in ways other than for which it was specifically approved. That said, the use of dutasteride certainly requires a doctor’s supervision.

Like finasteride (the active ingredient in Proscar and Propecia), dutasteride blocks the enzyme 5-alpha reductase that converts testosterone to DHT (DHT is a key hormone that causes hair loss). However, unlike finasteride, which only inhibits the Type I form of the enzyme, dutasteride inhibits both the Type I and Type II forms. This combined effect lowers circulating DHT more with dutasteride than with finasteride, but also increases the incidence of its side effects.

The Type II form of the enzyme (blocked by finasteride) is found predominantly in the hair follicle. The Type I form of the enzyme has been found in the scalp and sebaceous glands, and many other parts of the body, but its exact role in hair growth has not been determined. It is felt that dutasteride’s ability to dramatically lower serum levels of DHT is what makes it a more potent medication in hair loss.

When considering the safety of dutasteride, one should consider the following:

• It acts on other parts of the body besides the hair follicle.
• Unlike finasteride, where families that had a deficiency of the Type II 5-alpha reductase enzyme were followed for years without any adverse effects, there is no natural biologic model to show the safety of dutasteride.
• Dutasteride has been approved for prostate enlargement in an older male population. It is not approved for hair loss and, in fact, the clinical trials for hair loss were discontinued, so there is no safety data for its use in younger patients. There is a greater incidence of sexual side effects with dutasteride compared to finasteride.
• The 1/2 life of dutasteride is 5 weeks compared to 6-8 hours for finasteride. Serum concentrations of dutasteride are detectable up to 4-6 months after discontinuation of treatment.

A: First, you should discuss this with your prescribing physician. In my practice, I generally advise patients to:

• Discontinue the Propecia until the side effects have gone
• For 2 weeks, take 1/4 pill a day
• If there are no problems, for the next 2 weeks take 1/2 pill every day
• If you still do not have side effects, return to full dose of 1 pill every day
• If you experience side effects, go back to the level that you had no problem and stay at that level for at least 1-2 months before trying to increase the dose again