Five Things You May Not Know About Finasteride

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finasteride propecia chemical drawing1. Finasteride really does work

Finasteride (Propecia) is a medication that has been used for years for the management of male pattern hair loss. It is a 5-alpha reductase inhibitor, which decreases levels of dihydrotestosterone (DHT). The pivotal studies showed significant benefit for men with respect to slowing down hair loss. In addition, a meta-analysis (an analysis of multiple studies on the same subject) by Gupta and Charrette showed that 5-alpha reductase inhibitors are significantly more effective than placebo in increasing hair counts.

2. It does have sexual side effects but it is not high risk

A very common question is about the sexual side effects of Propecia. Sexual side effects from finasteride have been well-described and include erectile dysfunction and decreased libido. However, the true risk of adverse sexual side effects remains controversial. Some meta-analyses show an increased risk and some show no increased risk. However, a recent 2018 report published by Lee et al analyzed randomized, double-blind, placebo-controlled trials (the best kind) and found 15 such trials. The data from these studies were analysed together in a meta-analysis. The relative risk was approximately 1.66. In layman’s terms, if 1 out of 100 untreated people were expected to develop sexual side effects, then 1.66 out of 100 treated people would be expected to develop these side effects. This is not a huge increase.

3. It only works as long as you take it

I frequently get asked “What happens if I stop taking Propecia?” Unfortunately, the benefits only last as long as finasteride is being taken. Studies show that hair counts drop back to pre-treatment levels within one year of discontinuation of the medication. On the other hand, you can stop it anytime you choose. You don’t have to take the medication any longer than you want to. If you decide six months from now that your hair loss is not an issue anymore, you can stop it completely with no ill effects.

4. ‘Post Finasteride Syndrome’ may or may not exist

Depression and suicidal ideation have also been described in some small and uncontrolled studies. Some authors have called this “post-finasteride syndrome.” At this point, the quality of the studies has been low, the numbers are very small, and it is controversial whether this truly exists. At this point, I am not certain if this is a true phenomenon or not.

5. You can take Propecia if you are trying to conceive (as long as you are a man)

I have also been asked about whether it is safe for a man to take Propecia when trying to conceive. The levels of finasteride are very low in semen and thus it is completely safe to a pregnant women and to her fetus. On the other hand, a pregnant woman should never take finasteride herself while pregnant as this could affect the fetus.

Recently, I was asked if it was wise to take Propecia if the couple was trying to conceive and was having difficulty conceiving. One randomized, placebo-controlled study looked the effects of finasteride on semen and found there was no effect. Another randomized, double-blind, placebo-controlled trial showed some mild effects on sperm motility. With this in mind, I think it is safe to use Propecia in the average, healthy person. However, if the patient is having difficulty conceiving, then Propecia should not be used while trying to conceive.

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