Key takeaways:
Finasteride (Propecia, Proscar) is a medication used to treat benign prostatic hyperplasia (BPH) and male-pattern hair loss. It’s more likely to cause side effects at the higher dosage (5 mg) used to treat BPH.
Common finasteride side effects include erectile dysfunction and decreased sex drive. Depression, enlarged breasts in males, and low blood pressure are also possible.
Finasteride side effects may improve over time, and often go away on their own once you stop taking it. But in some cases, you may continue to experience side effects even after you stop taking the medication (post-finasteride syndrome).
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Finasteride (Propecia, Proscar) is a medication with two different uses. Proscar treats enlarged prostates caused by benign prostatic hyperplasia (BPH). Propecia, a lower dose of finasteride, treats male-pattern hair loss.
No matter what you’re taking finasteride for, it’s common to wonder about its possible side effects and how to manage them. We’ll discuss that, and when to seek medical care for side effects, below.
Finasteride side effects at a glance
Most finasteride side effects are hormone-related. This is because it lowers levels of a hormone called dihydrotestosterone (DHT) in the body. Most side effects are more likely with the higher (5 mg) dosage used to treat BPH. The lower (1 mg) finasteride dose for hair loss is most often associated with sex-related side effects.
Common finasteride side effects include:
Erectile dysfunction
Reduced libido (sex drive)
Decreased sperm count
Ejaculation issues
Rare finasteride side effects include:
Gynecomastia (male breast enlargement)
Low blood pressure
Breast tenderness
Skin rash
Testicular pain
Depression
Increased risk of prostate cancer and male breast cancer
Birth defects if taken or handled when pregnant
Allergic reactions
Below, we’ll go into more detail about six possible finasteride side effects and how to manage them.
1. Erectile dysfunction
Erectile dysfunction (ED) is the most commonly reported finasteride side effect. You may have trouble getting or maintaining an erection. You may also have a lower amount of ejaculate, due to finasteride’s effects on your prostate.
ED symptoms may improve over time as your body adjusts to the medication. But in the meantime, talk to your prescriber about treatment options. There are several ED medications you can take with finasteride to help manage this side effect. So don’t hesitate to let your healthcare team know if it’s a problem for you.
2. Decreased sex drive
A decrease in sex drive (low libido) is a possible finasteride side effect. Your sex drive may improve over time as your body adjusts to the medication. But it may also persist for some people.
Keep in mind that stress and lack of sleep can also lower your libido. So getting regular exercise, having good sleep habits, and eating a balanced diet may help give your sex drive a boost.
Let your healthcare team know if low sex drive is affecting your quality of life. They can suggest options for managing this side effect or switch you from finasteride to a different medication to see if that helps.
How long does finasteride (Propecia) take to work? Get the answer to this and other commonly asked questions about finasteride for hair loss.
Finasteride and alcohol: Here’s what you should know before having a drink while taking finasteride.
Finaseride vs. minoxidil: Review the key differences between these two hair-loss medications to help you find the right option for your needs.
Treatments for hair loss: Learn which hair-loss treatments work best, along with natural ways to help regrow hair.
3. Enlarged breasts in males
It’s not common, but enlarged breast tissue can develop in some men taking high-dose finasteride. Sore or tender breasts are also possible.
Breast-related side effects were only reported in clinical studies of the 5 mg finasteride dosage. There were no reports of these side effects with the 1 mg dosage. And unlike the previous side effects, the chance of breast-related side effects seems to go up the longer you take finasteride.
While this side effect can be concerning, it’s not usually dangerous to your health. It should go away once you stop taking finasteride. That being said, you should still let your medical care team know about any breast changes you experience. In rare cases, they may be a sign of male breast cancer that’s unrelated to finasteride.
4. Depression
Depression is another possible finasteride side effect. It wasn’t reported in initial clinical studies, but later reviews found a higher risk of depression and suicidal thoughts in people taking finasteride versus those who aren’t.
The sex-related side effects of finasteride may contribute to depression symptoms. And it’s possible for these symptoms to persist even after you stop taking finasteride — more on that later.
If you notice a change in your mood while taking finasteride, let your prescriber know. They can help determine the best way to manage it.
If you or someone you know is having thoughts of suicide, you’re not alone, and help is available. Call the National Suicide Prevention Lifeline at 988, or text HOME to 741-741 to reach the Crisis Text Line.
5. Low blood pressure
Finasteride may raise your risk of orthostatic hypotension. This is when your blood pressure drops after you sit up or stand after lying down. It can make you feel dizzy or even pass out in some cases.
This side effect is more likely if you take finasteride along with an alpha blocker (another type of BPH medication). Tamsulosin (Flomax) and doxazosin (Cardura) are common examples.
It’s a good idea to take your time when sitting up or standing, especially when you first start taking finasteride. If you feel dizzy, sit down or hold on to someone or something for support to avoid falls. If this side effect becomes bothersome, let your prescriber know. They may need to adjust your medications to manage it.
6. Post-finasteride syndrome
Most finasteride side effects will resolve on their own after you stop taking the medication. But in rare cases, they may continue to be a problem for you. Finasteride side effects that last more than 3 months after stopping the medication are referred to as post-finasteride syndrome.
Post-finasteride syndrome can include:
Sexual side effects: Low sex drive or erectile dysfunction
Physical side effects: Enlarged breasts or chronic fatigue
Mental side effects: Depression or suicidal thoughts
It’s not clear how common post-finasteride syndrome is, since most cases are self-reported. And there’s no known treatment for it at this time. But your healthcare team can help you address individual symptoms. So be sure to let them know if you have lingering finasteride side effects after you’ve stopped taking it. The Post-Finasteride Syndrome Foundation can also provide resources and support.
Frequently asked questions
Weight gain wasn’t a reported finasteride side effect in clinical studies. If you’re noticing changes in your weight while taking finasteride, it’s best to speak to your healthcare team. They can help determine the cause and the best steps to address it.
If you stop taking finasteride, it’s likely that your BPH symptoms or hair loss will return. Finasteride only works for these conditions while you’re taking it. And it only takes a day or so to clear it from your body once you stop the medication. That being said, if you’re experiencing bothersome side effects from finasteride, in most cases they’ll go away once you stop taking it. Just be sure to talk to your prescriber before stopping finasteride on your own.
No, finasteride doesn’t lower testosterone levels. It stops testosterone from being turned into DHT (dihydrotestosterone), a hormone that contributes to hair loss and an enlarged prostate. So, finasteride lowers DHT levels, not testosterone levels. In fact, finasteride can actually increase testosterone levels by up to 25%, since it prevents testosterone from being converted into DHT.
Weight gain wasn’t a reported finasteride side effect in clinical studies. If you’re noticing changes in your weight while taking finasteride, it’s best to speak to your healthcare team. They can help determine the cause and the best steps to address it.
If you stop taking finasteride, it’s likely that your BPH symptoms or hair loss will return. Finasteride only works for these conditions while you’re taking it. And it only takes a day or so to clear it from your body once you stop the medication. That being said, if you’re experiencing bothersome side effects from finasteride, in most cases they’ll go away once you stop taking it. Just be sure to talk to your prescriber before stopping finasteride on your own.
No, finasteride doesn’t lower testosterone levels. It stops testosterone from being turned into DHT (dihydrotestosterone), a hormone that contributes to hair loss and an enlarged prostate. So, finasteride lowers DHT levels, not testosterone levels. In fact, finasteride can actually increase testosterone levels by up to 25%, since it prevents testosterone from being converted into DHT.
The bottom line
Finasteride is a medication used to treat benign prostatic hyperplasia (Proscar) and male-pattern hair loss (Propecia). Common finasteride side effects include a reduced sex drive and erectile dysfunction. Depression, enlarged breasts in men, and low blood pressure are also possible. Most finasteride side effects are more likely with the higher 5 mg dose used for an enlarged prostate.
Some finasteride side effects may improve over time. But others may continue even after you stop taking it. It’s best to discuss the risks and benefits of finasteride with your prescriber before you start the medication. And let them know if you develop any bothersome side effects.
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References
Anitha, B., et al. (2009). Finasteride-Its impact on sexual function and prostate cancer Journal of Cutaneous and Aesthetic Surgery.
Diviccaro, S., et al. (2020). Post-finasteride syndrome: An emerging clinical problem. Neurobiology of Stress.
Irwig, M. S. (2012). Depressive symptoms and suicidal thoughts among former users of finasteride with persistent sexual side effects. The Journal of Clinical Psychiatry.
Nackeeran, S., et al. (2021). Erectile dysfunction is a modifiable risk factor for major depressive disorder: Analysis of a federated research network. The Journal of Sexual Medicine.
Pompili, M., et al. (2021). Risk of depression associated with finasteride treatment. Journal of Clinical Psychopharmacology.
Post-Finasteride Syndrome Foundation. (n.d.). PFS by the numbers.
Remedy Repack. (2025). Finasteride- finasteride tablet, film coated [package insert].
Zito, P. M., et al. (2024). Finasteride. StatPearls.
