Fact or Fiction: Diving Into the Side Effects of Finasteride

Dr. Patrick Carroll, MD
Medically reviewed by Patrick Carroll, MD Written by Our Editorial Team Last updated 9/5/2019

Finasteride is one of the most popular medications for men looking to stop hair loss. It’s one of the few androgenic alopecia treatments that’s been approved by the FDA specifically for hair loss. 

And it’s easy to see why. By itself, finasteride has been shown to be 85 percent effective in inducing hair growth within the first three to four months among the men who take it, it comes in the form of a once-daily oral pill that’s easy to take and with continued use under the right care and supervision of a doctor, it can essentially help stop hair loss in its tracks.

But does finasteride come with a risk of side effects? The short answer is “yes.” 

However, there’s a lot of misinformation surrounding finasteride and its potential side effects, and it's worth clearing the air. Finasteride does come with a risk of experiencing some side effects, as all drugs do, but the vast majority of men who use it benefit from a successful hair loss treatment without experiencing any undesired results. That said, if you’re considering taking finasteride or you are already on it, it’s good to understand what to expect.  

Let’s take a look at a couple of finasteride’s well-known side effects so that we can separate the fact from the fiction.

Does Finasteride Kill Your Sex Drive?

There’re some flashy headlines circulating the internet suggesting that taking finasteride will give you irreversible erectile dysfunction or kill your libido for good. While it is true that FDA issued a warning in 2012 that finasteride increases the risk of experiencing sexual side effects, including libido, ejaculation and orgasm disorders, those headlines don’t tell the full story.

Sexual dysfunction — generally in the form of erectile dysfunction, decreased libido and smaller ejaculate volume — has been experienced by men taking finasteride, which is what prompted the FDA in 2012 to call attention to the matter. 

But what the FDA noted is it’s also pretty rare. Only a small percentage of men taking finasteride reported experiencing a sexual side effect like a decrease in libido, erectile dysfunction, or problems with ejaculation. For some of these men, the side effects persisted even after stopping treatment. Most of the time, though, the side effects stopped when treatment stopped.

Even though the risk of experiencing sexual side effects is low, it’s totally normal to be concerned about that potential risk. Be sure to let your doctor know your concerns before you start taking finasteride. And if you are one of these rare cases, it’s important to contact your doctor before continuing to use finasteride.

Can Finasteride Cause Cancer

Finasteride is a generally safe and well tolerated medication in the overwhelming majority of men who take it. However, one point of contention among researchers is whether or not long-term use of finasteride carries the potential for prostate cancer risks or benefits.

Perhaps the most commonly referenced research on the topic, the Prostate Cancer Prevention Trial (PCPT) is a study funded by the National Cancer Institute (NCI) in 1993 to specifically explore the potential link between finasteride and prostate cancer.

The study took place over seven years and included nearly 19,000 men who took either finasteride or a placebo daily. The results of the study, released in 2003, found that the men in the finasteride group were nearly 30 percent less likely to get prostate cancer than men in the control group. 

Ok, so one point in the cancer benefit column.

However, the study also found that men who took finasteride were at greater risk of developing high-grade prostate cancer (high-grade cancer cells are more abnormal under a microscope and tend to spread faster). 

This finding prompted the FDA to release a safety announcement regarding 5-alpha reductase inhibitors (including finasteride), noting the potential for increased risk of high grade prostate cancer. So this original study tied up the score and it has been this way for quite some time.

The most recent development in this line of research came in 2019 and was interesting. 

In short, researchers found no increase in the number of men who’d died of prostate cancer between the finasteride and control groups. So given 20 years of follow up, there is no measurable difference in prostate cancer mortality between the groups. 

Experts have said that this goes a long way to alleviate concerns, but given the small number of men with lethal prostate cancer in both study arms, it will likely continue to be an area of ongoing research

The interplay of finasteride and cancer continues to evolve. If you’re considering taking finasteride daily to help with your hair loss, check with your physician about the potential risks.

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Finasteride and the Bottom Line

The difference between finasteride and other drugs or unregulated hair loss medicines is that finasteride is well studied and only a small percentage of its users will experience side effects. 

Although experienced in a low percentage of men taking finasteride there are other potential side effects you should know about, including breast tenderness, rashes, depression, anxiety, testicular pain and neurological issues like mental fogginess. Make sure that you talk with your doctor and disclose any medical history before beginning finasteride. 

There’s also a link between finasteride’s sexual side effects and the use of NSAIDS like Motrin®, Advil® and Aleve®.

Additionally, finasteride should not be taken if you have chronic liver disease. 

The best thing to do is schedule an appointment with your doctor to determine what the best plan of action should be.

For most men, finasteride is a great way to stop the effects of male pattern baldness dead in their tracks.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.