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Finasteride Side Effects Guide

Kristin Hall, FNP

Medically reviewed by Kristin Hall, FNP

Written by Our Editorial Team

Last updated 8/15/2021

Finasteride is one of the most popular and effective medications for men looking to prevent hair loss. It’s also one of the few androgenetic alopecia (male pattern baldness) treatments that has been approved by the FDA. 

It’s easy to see why. Used on its own, finasteride has been shown to stop hair loss and improve hair growth in the majority of men, often within three to four months.

Finasteride comes in tablet form and is designed for use one time per day. It’s easy to use and, under the supervision of a healthcare professional, can stop male pattern baldness in its tracks without the need for costly cosmetic procedures.

But does finasteride come with a risk of side effects? The short answer is, well, yes. Like other medications, finasteride can cause side effects. 

However, there’s a lot of misinformation about finasteride and its potential side effects out there.

In general, the risk of side effects from finasteride is low. Research shows that the majority of men who use finasteride over the long term benefit from a successful hair loss treatment with few or no undesired results.

With this said, if you’re considering using finasteride, or if you’re already taking it, it’s important to understand what to expect.

Below, we’ve listed the common and uncommon side effects you may experience while taking finasteride for hair loss

We’ve also talked about what you can do to reduce your risks of developing side effects while using finasteride.

Common Side Effects of Finasteride

Like other FDA-approved medications, finasteride was put through a thorough testing process before it went on sale. 

Because of this, lots of data is available about its potential side effects, risks and interactions.

When looking into the side effects of finasteride, it’s important to be aware that two versions of finasteride are available.

The first is Propecia®, the form of finasteride that’s used to treat hair loss. This is available in a 1mg dosage and is designed for use once per day.

The second is Proscar®, a high-strength version of finasteride that’s prescribed to treat benign prostatic hyperplasia, or BPH. 

This medication contains 5mg of finasteride per tablet. Due to its higher dosage, it’s more likely to cause certain side effects.

Common side effects of 1mg finasteride (the dosage used to treat hair loss due to male pattern baldness) include:

  • Erectile dysfunction (ED). In clinical trials, approximately 1.3 percent of men who used finasteride experienced erectile dysfunction, compared to 0.7 percent of men who took a non-therapeutic placebo.

  • Decreased libido. This was reported by 1.8 percent of men who took finasteride and 1.3 percent of men who were given a non-therapeutic placebo.

  • Ejaculation disorder. In total, 1.2 percent of men who used finasteride reported issues related to ejaculation, with 0.8 percent reporting a lower semen volume. In comparison, 0.4 percent of men who used a placebo treatment reported lower semen volume.

In total, only 1.2 percent of the men who were given finasteride in clinical trials discontinued the medication due to side effects.

These side effects are much more common in men who use the 5mg version of finasteride as a treatment for BPH. 

For example, more than eight percent of men who use 5mg finasteride develop some degree of erectile dysfunction, with more than six percent reporting a decreased libido.

Overall, even the most common side effects of finasteride only affect a small percentage of men when this medication is used to treat hair loss.

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Less Common Finasteride Side Effects

Finasteride may also cause other, less common side effects. These include depression, pain in the testicles, changes in the breasts (for example, male breast growth, lumps, pain or discharge from the nipples), itching, rash, hives, facial swelling and difficulty breathing or swallowing. 

If you are experiencing any of these side effects you should immediately report this to a healthcare provider as they can indicate a severe allergic reaction that may be life threatening.

Some of these side effects may be more common if you take finasteride at a higher dosage than the 1mg per day that’s typically prescribed to treat hair loss

If you experience any of these side effects while you’re taking finasteride, it’s important to talk to your healthcare provider as soon as possible.

How to Reduce Side Effects From Finasteride

Side effects are an unfortunate reality of almost all medications. However, using finasteride the right way may reduce your risk of developing side effects. 

Try the following tips and techniques:

  • Use the correct dosage. As a treatment for hair loss, finasteride is used at a dosage of 1mg per day. There’s no need to take more than this -- it won’t improve your results, but it may increase your risk of developing side effects.

  • If you forget a dose, skip it and wait for the next one. There’s no need to take double the normal dose of finasteride. Doing this may increase your risk of facing side effects in the short term.

  • Use topical finasteride. Finasteride is also available as a topical medication, such as in our Topical Finasteride & Minoxidil Spray. This form of finasteride may offer a lower side effect risk than oral finasteride, all while still treating hair loss. Read our guide on topical finasteride side effects for more information.

  • If you develop side effects, let your healthcare provider know. In certain cases, side effects are a temporary annoyance. Make sure to inform your healthcare provider so that they can track your progress and, if necessary, provide expert advice.

  • Take finasteride at a lower dosage. If you experience severe or persistent side effects, your healthcare provider may recommend taking finasteride at a lower dosage. 

Does Finasteride Kill Your Sex Drive?

If you search online for information about finasteride, you may come across headlines claiming that taking finasteride will give you irreversible erectile dysfunction and kill your libido for good. 

While it’s true that finasteride can cause sexual side effects, these headlines don’t really tell the full story.

In 2012, the FDA issued a warning stating that finasteride can increase a person’s risk of facing sexual side effects, including a libido, ejaculation and orgasm disorders.

Sexual dysfunction, generally in the form of erectile dysfunction, decreased libido and reduced ejaculate volume, has been experienced by men taking finasteride. 

This is what prompted the FDA in 2012 to call attention to the matter.

But the FDA also noted that these side effects are pretty rare. Only a small percentage of men who use finasteride report experiencing any sexual side effects.

For some of these men, the sexual side of finasteride effects persisted even after they stopped using this type of medication. Most of the time, though, the side effects stopped when treatment stopped.

Even though the risk of experiencing sexual side effects is small, it’s normal and understandable to be concerned about this potential risk.

Be sure to let your healthcare provider know about any of your concerns before you start to use finasteride. 

They’ll be able to put these risks in context and provide more information about what you can expect after starting finasteride. 

If you are one of these rare cases of recurring sexual side effects, it’s important to talk with your healthcare provider to find out about your options. 

Can Finasteride Cause Cancer?

Finasteride is a safe and well-tolerated medication that’s used by millions of men worldwide, all without any significant problems.

However, one point of contention among experts 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), was a study funded by the National Cancer Institute (NCI) in 1993 specifically to explore the potential link between finasteride and prostate cancer.

The study was carried out over seven years and included nearly 19,000 men who used either finasteride or a placebo daily.

The findings of the study, published 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 concluded that men who took finasteride 5mg were at greater risk of developing high-grade prostate cancer (high-grade cancer cells are more abnormal under a microscope and tend to spread throughout the body 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. This original study tied up the score and it’s been this way for quite some time.

The most recent development in this line of research came in 2019, when researchers found no increase in the number of men who had passed away due to prostate cancer between the group that used finasteride and the control group.

So, given 20 years of follow up, there is no measurable difference in prostate cancer mortality between the groups.

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

In conclusion, the interplay of finasteride and cancer continues to evolve. If you’re considering taking finasteride daily to help with your hair loss, make sure to discuss the potential risks with your healthcare provider. 

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Finasteride Side Effects: The Bottom Line

Finasteride is a safe and effective medication that’s used by millions of men worldwide to slow down, prevent and reverse the effects of male pattern baldness.

Research shows that only a small percentage of men who use finasteride experience any side effects. 

Of these side effects, the most common are erectile dysfunction, ejaculation disorders and a reduced level of interest in sex

Although other side effects can occur, they’re uncommon and, for most men, cease to occur if treatment with finasteride is stopped.

While finasteride’s side effects may seem alarming, it’s important to keep them in context. The reason we know about these mild, uncommon side effects is that finasteride has been studied for decades and put through the most rigorous testing processes available.

The same can’t be said for the vast majority of unregulated hair loss treatments, such as many of those promoted as non-prescription finasteride alternatives.

We offer finasteride online, either by itself or with minoxidil in our Hair Power Pack. To access finasteride, you’ll need to complete an online consultation with a licensed healthcare provider, who will determine if a prescription is appropriate.

You can also view other options for protecting and restoring your hair in our complete range of hair loss treatments. If you’re interested in using finasteride, you can learn more about what to expect in our guide to the typical finasteride results timeline.

8 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. PROPECIA® (finasteride) tablets for oral use. (2012, April). Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/020788s020s021s023lbl.pdf
  2. Finasteride. (2018, January 15). Retrieved from https://medlineplus.gov/druginfo/meds/a698016.html
  3. Roberts, J.L., et al. (1999, October). Clinical dose ranging studies with finasteride, a type 2 5alpha-reductase inhibitor, in men with male pattern hair loss. Journal of the American Academy of Dermatology. 41 (4), 555-63. Retrieved from https://pubmed.ncbi.nlm.nih.gov/10495375/
  4. Questions and Answers: Finasteride Label Changes. (2016, April 13). Retrieved from https://wayback.archive-it.org/7993/20170723090425/https://www.fda.gov/Drugs/DrugSafety/InformationbyDrugClass/ucm299754.htm
  5. Prostate Cancer Prevention Trial (PCPT): Questions and Answers. (2013, August 14). Retrieved from https://www.cancer.gov/types/prostate/research/prostate-cancer-prevention-trial-qa
  6. FDA Drug Safety Communication: 5-alpha reductase inhibitors (5-ARIs) may increase the risk of a more serious form of prostate cancer. (2011, June 9). Retrieved from https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-5-alpha-reductase-inhibitors-5-aris-may-increase-risk-more-serious
  7. Darke, A.K., et al. (2019, January 24). Long-Term Effects of Finasteride on Prostate Cancer Mortality. New England Journal of Medicine. 380, 393-394. Retrieved from https://www.nejm.org/doi/full/10.1056/NEJMc1809961
  8. Prostate Cancer Prevention and Finasteride: A Conversation with NCIs Dr. Howard Parnes. (2019, May 13). Retrieved from https://www.cancer.gov/news-events/cancer-currents-blog/2019/prostate-cancer-prevention-finasteride-parnes

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.