Finasteride is a DHT-blocking prescription medication used to treat male pattern hair loss. You might know better by its brand names, Propecia or Proscar.

There are a lot of rumors out there about this drug and its side effects. Being curious—or even concerned—about finasteride’s side effects is completely fair. Before you take any medication (or really make any decisions involving your own healthcare), you should always do your research and make sure you’re comfortable with your treatment plan. To make that easier for you, we went ahead and summed up the important facts below.

If you’d rather watch than read, check out this quick explainer from hair loss expert Dr. Jerry Shapiro:

Finasteride’s side effects

Yes, like any drug, there might be side effects. Some of the possible side effects of taking finasteride 1mg include:

  • depression or anxiety
  • dizziness, weakness, or feeling like you might pass out
  • headache
  • inability to urinate
  • pain in the testicles
  • runny nose
  • rash
  • signs of an allergic reaction like skin rash, itching, difficulty breathing, swelling of the face, lips, or tongue
  • sexual side effects (more on that below)
  • swelling in your hands or feet
  • swelling, pain, or tenderness in the breasts, or fluids leaking from the nipple

Finasteride’s sexual side effects

Let’s just jump right into what’s likely your biggest fear though: erectile dysfunction. Or, more specifically, the fear that taking finasteride will disrupt your sex life.

Though rare, in clinical trials, 3.8% of male patients noticed some form of sexual side effects (versus 2.1% of patients using the placebo), including less desire for sex, difficulty in achieving an erection, or a decrease in the amount of semen released during sex. This may continue after stopping treatment.

The number to focus on there is 3.8%. It’s small. Now, that’s not to diminish your concern or to say that the 3.8% people experiencing these symptoms don’t matter—but rather to point out that this isn’t a guaranteed side effect of taking finasteride. Despite what you may hear, for 96% of men, taking this common hair loss medication doesn’t mean you have to choose between your sex life and your hairline. Plus, it’s important to note that 2.1% of men using the placebo experienced the same side effects.

Now, you might be wondering what happens if you’re part of that 3.8% who experiences side effects. You might’ve even heard about post-finasteride syndrome, a non-medical term used to describe a variety of long-term side effects reported by a small number of men even after they stopped taking the medication.

Well, the good news is that hair loss experts say there’s little scientific proof that finasteride actually causes post-finasteride syndrome. This means that very few men continue to experience side effects after stopping treatment.

Who shouldn’t take finasteride

Regardless of the side effects, some people should avoid finasteride altogether. Women shouldn’t take it because it can affect hormone levels. It’s very important that women who are pregnant or could become pregnant don’t handle finasteride, as it can lead to complications with pregnancy.

Don’t take finasteride if you have any of the following conditions:

  • Kidney problems
  • Liver disease or other liver-related issues
  • Prostate cancer
  • You are allergic to finasteride, Proscar®, or Propecia®
  • You are breastfeeding
  • You are pregnant or trying to get pregnant

A few other things to be cautious of

You should avoid excessive alcohol consumption while taking finasteride. You should also know that finasteride can interfere with PSA laboratory tests, which are used to screen for prostate cancer. If you’re scheduled to be tested for prostate cancer, you should let your doctor know that you’re taking this medication (and any other medications you’re taking).

Despite what you might’ve heard, taking finasteride doesn’t cause prostate cancer. Studies show that it can actually decrease your overall risk of getting prostate cancer, although if you do develop it, it’s slightly more likely to be high-grade. In fact, at higher doses, finasteride is actually used as a treatment for enlarged prostates.

With all that said, you should make the decision that’s right for you. And to do that, we always recommend contacting your doctor if you have questions about finasteride. You may also report side effects to the FDA at 1-800-FDA-1088.

Photo by Jarrod Reed on Unsplash

The information provided in this article is not a substitute for professional medical advice, diagnosis, or treatment. You should not rely upon the content provided in this article for specific medical advice. If you have any questions or concerns, please talk to your doctor.

If you’re experiencing a mental health crisis, please call 911 or go to your nearest emergency department. If you are contemplating suicide, call 911 or call/text the National Suicide and Crisis Lifeline at 988. These services are available 24/7.

If you would like to learn more about finasteride, please see the full prescription information here. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit MedWatch:   or call 1-800-FDA-1088