Does Finasteride Cause Erectile Dysfunction?

Key Takeaways 

• Finasteride can cause erectile dysfunction, but this is uncommon and affects only a small minority of users (around 2–4%).

• Most men do not experience any sexual side effects, and many who do find they resolve either while continuing treatment or shortly after stopping.

• Finasteride lowers dihydrotestosterone (DHT), which can affect erectile function in some men, but this does not explain all reported cases.

• Expectations matter more than many realise: men who worry about side effects are more likely to report them

• Reports of persistent symptoms after stopping finasteride exist, but current evidence does not confirm this as a common or inevitable outcome.

• Erectile dysfunction is influenced by many factors, including stress, mental health, cardiovascular health, sleep, alcohol, and medications, not just finasteride.

• Side effects are usually manageable through medical guidance, dose adjustment, or switching to topical alternatives.

Finasteride can cause erectile dysfunction in some men, but it isn’t common. Most men who notice changes find that things improve after stopping the medication or adjusting the dose.

In this article, we’ll look at what the research shows about erectile dysfunction, why it happens in some men, and what you can do if it occurs.

What Is Finasteride and How Does It Work?

Finasteride, also known by its brand names Propecia or Proscar, is the gold standard medication used to treat male pattern baldness, as well as a first-line treatment for benign prostatic hyperplasia (BPH) or an enlarged prostate.¹ 

It works by inhibiting the enzyme 5-alpha reductase, which converts testosterone into DHT, a hormone that contributes to hair loss and prostate enlargement.

Finasteride can reduce DHT levels by up to 70%, helping slow hair follicle damage.² While this is beneficial, for patients whose hair is sensitive to changes in this hormone, a reduction in DHT can cause rare and unwanted side effects.

Does Finasteride Cause Erectile Dysfunction? What the Evidence Shows

Clinical trials show that sexual side effects do occur, but in a small minority of users. 

In men taking 1 mg daily for hair loss, around 2–4% reported:

• erectile dysfunction
• reduced libido
• reduced ejaculate volume³

How finasteride affects erections in some men

Erectile function depends on hormones, blood flow, and nerve signalling. Finasteride changes hormone levels, which in some men can affect sexual function.

1. Reduced DHT can slightly weaken the erection signalling

DHT helps maintain smooth muscle health in the penis and supports nitric oxide (NO) production, the chemical signal that allows blood to flow into erectile tissue.⁴

When DHT falls, this signalling may become less efficient in some men, making erections feel weaker or less reliable.

2. Hormonal balance shifts

Blocking DHT slightly increases testosterone (around 10–15%). For most men, this causes no issues. In a few, this altered balance can influence libido or erectile quality.

This explains the biological pathway. But biology alone doesn’t tell the whole story.

Why do some men notice symptoms while others don’t?

Erectile function is one of the most psychologically sensitive systems in the body.

Stress, fear, and expectation alone can disrupt the brain–body signals that produce an erection.

This is where the nocebo effect becomes important. The nocebo effect occurs when someone experiences side effects simply because they expect them.

A landmark study demonstrated this clearly, where 120 men with prostate issues were split into two groups:⁵

• One group was warned about possible sexual side effects

• The other group was not

The men who were warned were nearly three times more likely to report erectile dysfunction.

Nothing in their bodies was different; only their expectations were.

This suggests that for a significant proportion of users, symptoms are not driven by hormones alone, but by anxiety and anticipation.

Other Factors That Can Affect Erectile Function

It’s important to remember that ED is common even in men not taking finasteride. Other contributing factors include:⁶

• Stress, anxiety, or performance pressure

• Depression

• Fatigue or poor sleep

• Alcohol or smoking

• Certain medications (e.g. antidepressants, blood pressure drugs)

• Cardiovascular health

This means that ED developing while on finasteride is not automatically caused by the medication.

For my patients who do suffer from erectile dysfunction whilst taking Finasteride, we have an in-depth consultation about the circumstances of their dysfunction. Most times, it is circumstantial with stress playing a role in their experience. For patients who do worry about erectile dysfunction whilst on Finasteride, we are able to counsel about stopping the medication, reducing its dose or switching to an alternative. 

Dr Roshan Vara, Co-Founder and Surgeon at The Treatment Rooms London

Is Erectile Dysfunction After Finasteride Permanent or Temporary?

For most men, any sexual side effects are temporary. Erectile function usually returns while continuing the drug or shortly after stopping.

There is a very small risk that symptoms could persist in some patients, an area sometimes referred to as post-finasteride syndrome (PFS).⁷

Post-finasteride syndrome 

Some men report persistent sexual or mood changes after stopping finasteride, including:⁸

• Erectile dysfunction
• Decreased libido
• Fatigue
• Mood changes

PFS is controversial. Evidence is inconsistent, and the exact mechanism is unclear. Some researchers suggest psychological factors or unrelated health issues, while others hypothesise long-term hormonal alterations may play a role.⁷

Currently, there is no clear proof that persistent effects are common or inevitable.

What to Do if You Experience ED on Finasteride

If you notice sexual changes, the first step is not to panic. Stress can worsen symptoms. A standard clinical approach may include:

1. The “Wait and See” Period (2–4 Weeks)

Clinical data show that, for some men, mild side effects occur as the body adjusts to reduced DHT levels. In many cases, these symptoms resolve on their own within a few weeks without stopping the medication. If symptoms are mild, your doctor may suggest staying the course for a short period to see if your hormonal balance recalibrates.

2. Consult Your Prescribing Doctor 

Do not simply stop or change your dosage without professional guidance. A GP or specialist will need to rule out other factors. 

3. Dose Titration (Frequency Adjustment)

Rather than quitting entirely, many clinicians recommend titrating the dose. The standard dose is 1mg daily. However, because Finasteride binds to the 5-alpha reductase enzyme in the skin for several days, some men find success by reducing the frequency, for example, taking 1mg every other day or three times a week. This can often reduce systemic side effects while still providing enough DHT suppression to protect hair follicles.

You can read our blog on Can you take Finasteride 3 times a week.

4. Switching to Topical Finasteride

Topical formulas are applied directly to the scalp. This targeted approach theoretically reduces the amount of the drug circulating in your bloodstream. Transitioning from oral to topical is a common and effective way to prevent hair loss while eliminating sexual side effects.

5. The Washout Period

If side effects are persistent or distressing, your doctor will likely advise you to stop the medication. Because Finasteride has a short half-life (about 6–8 hours), it clears from the bloodstream quickly, but hormonal recovery may take longer. Most men find that sexual function returns to normal within 5 to 7 days after the final dose, though it may take a few weeks for the enzyme levels to fully recover.

What Alternative Hair Loss Treatments Are Available If You Experience Erectile Dysfunction?

In case you suffer from erectile dysfunction while taking Finasteride, you may want to switch to another treatment to help prevent hair loss.

Minoxidil– this is a medication you apply topically to your scalp or take orally. It helps to stimulate hair growth.

Platelet-Rich Plasma (PRP therapy) utilises the blood plasma, which carries growth factors in your blood, to rejuvenate inactive hair follicles and enhance scalp health.

Microneedling works by creating minor, controlled injuries to the scalp that improve blood flow, stimulate new hair growth, and increase the absorption of topical treatments, such as topical Minoxidil.

Low-level laser therapy (LLLT) uses light energy to enhance cell activity in hair follicles and retard hair thinning.

These treatments do not have an impact on your hormone levels, and thus, they are a good option for men who suffer from ED or other side effects of oral DHT blockers like Finasteride or Dutasteride.

Conclusion 

Finasteride remains one of the most effective treatments for male pattern hair loss. While sexual side effects are possible, they are uncommon and usually temporary.

If you are concerned, speak with a healthcare professional. They can guide you on dosing, monitoring, and alternatives.

For ongoing hair loss despite medication, a surgical consultation with a qualified surgeon may help determine whether a hair transplant is appropriate.

References 

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2. Miller MG, Brown DuTeaux S. Finasteride. In: Encyclopedia of Toxicology (Second Edition). Elsevier; 2005. Available from: https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/finasteride

3. Mysore V. Finasteride and sexual side effects. Indian Dermatol Online J. 2012 Jan-Apr;3(1):62–65. doi:10.4103/2229-5178.93496. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3481923/

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6. DeLay KJ, Haney N, Hellstrom WJG. Modifying Risk Factors in the Management of Erectile Dysfunction: A Review. World J Mens Health. 2016 Aug;34(2):89–100. doi:10.5534/wjmh.2016.34.2.89. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4999494/

7. Irwig MS. Persistent sexual side effects of finasteride: could they be permanent? J Sex Med. 2012 Nov;9(11):2927–2932. doi:10.1111/j.1743-6109.2012.02846.x. Available from: https://www.sciencedirect.com/science/article/abs/pii/S1743609515337863

8. Diviccaro S, Melcangi RC, Giatti S. Post-finasteride syndrome: An emerging clinical problem. Neurobiol Stress. 2020;12:100209. doi:10.1016/j.ynstr.2019.100209. Available from: https://www.sciencedirect.com/science/article/pii/S235228951930061X