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Finasteride Side Effects

Finasteride Side Effects and Safety — What to Know Before Using this Treatment

Finasteride is one of the most commonly used hair loss treatments around the world. It’s popular because it works: it has been shown time and time again to effectively reduce hair loss and even regrow hair.

But it can lead to some side effects. Being aware of these can help you choose the most appropriate hair loss treatment option for you.

In this article, we cover everything you need to know about finasteride side effects—what to expect, how to avoid them, and what some finasteride alternatives could be.

How Does Finasteride Work?

Finasteride is a prescription medication. It is often used to treat male-pattern hair loss (androgenic alopecia) in adult men, although it is also used to treat benign prostatic hyperplasia (enlarged prostate). For hair loss, it’s usually taken orally as a tablet at a dose of 1 mg. Finasteride is the generic version of the brand name drug Propecia.

Read more: Propecia vs. Generic Finasteride

To understand how finasteride works—and how it can cause side effects—we need a quick biology lesson. Androgenetic alopecia is caused by a hormone called dihydrotestosterone (DHT). DHT miniaturizes hair follicles: it makes them smaller and smaller, creating increasingly fine hair. Eventually, the follicles become so small that the hair falls out and the follicle dies.

So, to address hair loss, we need to reduce DHT in the scalp. DHT is created as a byproduct when testosterone is broken down. And there’s an enzyme, called 5α-reductase, that’s part of the process where testosterone is broken down.

Finasteride works by inhibiting 5α-reductase. Reducing 5α-reductase means less testosterone is broken down, which means less DHT, which ultimately means less hair loss. That’s what makes it effective: research finds that finasteride reduces hair loss in 90% of men with androgenic alopecia. In one long-term, 10-year study, 99% of men taking finasteride had their hair loss stay the same or get better.

Read more: What is finasteride? Everything you need to know

Is Finasteride Safe?

Yes, finasteride is considered safe for most men. Decades of research have consistently shown that side effects are uncommon and are usually not severe. However, finasteride does have some potential side effects that you should be aware of.

Oral Finasteride side effects

The following are some more common side effects that finasteride may cause. If these symptoms are severe or do not go away, seek medical advice:

  • Pain in the testicles
  • Decreased libido
  • Inability to have or maintain an erection (erectile dysfunction)
  • Problems with ejaculation (including decreased volume of ejaculate)
  • Depressive symptoms and suicidal thoughts

Some side effects can be very serious. Seek immediate medical advice if you experience any of the following symptoms:

  • Symptoms of allergy, including rash, itching, hives
  • Swelling of the lips and face
  • Difficulty breathing or swallowing
  • Changes in the breasts such as increased size, lumps, pain, or nipple discharge

Note that most patients taking finasteride do not experience side effects. In one clinical study, only 3.8% of patients experienced side effects, compared with 2.1% in the placebo group. In other words, the difference in side effects reported by people actually taking finasteride and people _thinking_ they were taking finasteride was quite small.

Further, note that most research suggests that side effects are temporary. The side effects stop in most people after discontinuing treatment. While long-term side effects of finasteride can persist (called post finasteride syndrome), this is rare—persistent side effects occur in only 0.3% of men.

Does finasteride cause hair loss initially?

Yes, finasteride use can cause temporary shedding in some people. This is most likely to occur in the first few months of using it. It’s actually a good sign because it suggests that the medicine is working. It’s so common that it’s actually got a name: finasteride shedding or Propecia shedding.

It’s not exactly clear why this is. Some experts believe that it’s because finasteride may help restart the growth phase of the hair follicles. The follicles may shed the old hair to be able to grow back new hairs that are thicker.

In any case, this shedding is temporary. It is common in the first few weeks and months of the treatment, but eventually will go away. Shedding may be more likely if you also use minoxidil with finasteride.

Does finasteride cause high-grade prostate cancer?

No, the evidence does not suggest that finasteride causes prostate cancer. Research suggests that, in general, finasteride reduces the risk of getting low-grade prostate cancer.

However, there is some nuance here. In one randomized control study over seven years, initial results did suggest that while there was less prostate cancer in the finasteride group, there was a higher percentage of high-grade prostate cancer (6.4% in the finasteride group vs. 5.1% in the placebo group—the difference between them was just 1.3%).

However, with more follow-up over the next few years, researchers found that the difference was small and statistically insignificant. One replication study found that prostate cancer was significantly lower in the finasteride group (10.5% vs. 14.9%). High-grade prostate cancer was as common in the finasteride group (3.5%) as in the placebo group (3.0%). There was no statistically significant difference, meaning that the difference was so small and may be due to chance.

How to avoid the side effects of finasteride?

Most people taking finasteride will not experience an adverse event. But to decrease the risk of adverse effects, make sure you follow the directions of use of the medical professional who prescribed your finasteride. Ensure that you take the dose recommended to you.

Alternatives to oral finasteride

You can also potentially avoid the side effects of finasteride by exploring some alternatives. For example, topical finasteride may have fewer side effects than 1 mg finasteride tablets. Minoxidil may have fewer side effects as well.

Topical finasteride

Most people take finasteride orally in tablet form. However, there are also now several topical options available. Topical finasteride comes in a spray or gel. Instead of being absorbed systemically, it gets absorbed into your scalp and gets right to work inhibiting DHT in the hair follicles.

Topical finasteride is newer than oral finasteride, so there isn’t as much research on it. But the research evidence that does exist suggests that it is safe. No studies have reported serious side effects. The minor side effects reported include:

  • Scalp irritation
  • Erythema (reddening of the skin)
  • Itchy skin
  • Shedding

Topical finasteride may be a way to realize the benefits of finasteride without risking the sexual side effects.

Read more: Topical Finasteride in Canada: What it is, where to buy it, and more


Minoxidil is another hair loss treatment medication. It’s the generic name for Rogaine. Minoxidil works by dilating blood vessels in the scalp, allowing more blood and nutrients to get to the hair follicles. Minoxidil is also effective, although not as effective as finasteride.

However, it does have fewer side effects and is not associated with any sexual side effects. Minoxidil side effects include:

  • Shedding
  • Scalp irritation
  • Itchy skin
  • Erythema (reddening of the skin)

Read more: What is Minoxidil? Your complete guide to Minoxidil in Canada

Start your hair regrowth journey now

Finasteride is one of the most commonly prescribed medications for hair loss. There are decades of research demonstrating that it’s effective.

It can cause side effects, but these are generally uncommon and usually not severe. Only about 3.8% of people taking finasteride treatment can expect to experience an adverse reaction. But if you’re worried about the potential side effects of finasteride, there are many alternative treatments.

Not sure what treatment is right for you?

Start an online consultation with our medical professionals. They can give you more information about what medications may be appropriate for you and what alternatives you can seek to reduce the risk of side effects.


Lee, S. W., Juhasz, M., Mobasher, P., Ekelem, C., & Mesinkovska, N. A. (2018). A systematic review of topical finasteride in the treatment of androgenetic alopecia in men and women. Journal of Drugs in Dermatology, 17(4), 457.

McClennan, K. J., & Markham, A. (1999). Finasteride: A review of its use in male pattern baldness. Drugs, 57(1), 111-126.

Mysore, V. (2012). Finasteride and sexual side effects. Indian Dermatology Online Journal, 3(1), 62.

Shapiro, J., & Kaufman, K. D. (2003, June). Use of finasteride in the treatment of men with androgenetic alopecia (male pattern hair loss). In Journal of Investigative Dermatology Symposium Proceedings (Vol. 8, No. 1, pp. 20-23). Elsevier.

Thompson Jr, I. M., Goodman, P. J., Tangen, C. M., Parnes, H. L., Minasian, L. M., Godley, P. A., ... & Ford, L. G. (2013). Long-term survival of participants in the prostate cancer prevention trial. New England Journal of Medicine, 369, 603-610.

Yanagisawa, M., Fujimaki, H., Takeda, A., Nemoto, M., Sugimoto, T., & Sato, A. (2019). Long-term (10-year) efficacy of finasteride in 523 Japanese men with androgenetic alopecia. Clinical Research Trials, 5(5), 1-5.

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.