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What is finasteride?

Finasteride¹ (also called Propecia and ProsCAR) is a common prescription medication men take. Finasteride cannot be purchased over the counter.

Finasteride belongs to a category of drugs called 5-α reductase inhibitors.² Finasteride is normally prescribed in doses of 1mg or 5mg, depending on the condition and severity. 

What is it used for, and how does it work? 

Finasteride is used for treating prostate enlargement. This condition can cause troublesome urinary symptoms, including difficulty urinating, as the prostate grows and starts to block the urethra. It is also used to treat male pattern baldness (androgenetic alopecia). 

Male pattern baldness is an appearance-related condition with a distinct pattern where hair is lost from the top of the head first. Finasteride inhibits testosterone from being converted into dihydrotestosterone, particularly in the scalp, helping normalize hair follicle growth and preventing the progression of prostate growth in patients with BPH. 

Because it is a 5-α reductase inhibitor, finasteride uses an enzyme called 5-α reductase to stop testosterone from being converted into an active form called dihydrotestosterone (DHT). DHT is implicated in the pathophysiology of BPH and male-pattern baldness. 

However, decreased levels of dihydrotestosterone can also affect other functions in the body. This is why finasteride can cause side effects in various parts of the body, including sexual side effects. 

Can finasteride cause erectile dysfunction? 

Like any medication, finasteride has side effects. Many studies³ have shown a link⁴ between finasteride and erectile dysfunction (ED), a condition that involves ongoing difficulties getting or maintaining an erection. Finasteride also has other sexual side effects like low sex drive and difficulty with ejaculating. 

Finasteride causes erectile dysfunction in a small number of men that take it because of its effects on DHT and possibly testosterone, though some studies have found conflicting effects.

This active form of testosterone, DHT, seems more potent than testosterone in maintaining nitric oxide production in the corpus cavernosum, and maintenance of nitric oxide-induced erection is dependent on DHT in rats. Furthermore, finasteride also seems to directly affect the penile smooth muscle and the neurons. 

There are a few different factors that could affect your chances of getting erectile dysfunction on finasteride. This includes your age — older men are more likely to experience adverse effects on sexual dysfunction, which may include erectile dysfunction. 

Many other factors have been proposed as causing erectile dysfunction on this medication, such as poor diet and a lack of exercise. However, the evidence for these is very weak, and therefore, these aren’t considered causal. 

How long does it take to recover from erectile dysfunction caused by finasteride? 

If you experience erectile dysfunction while taking finasteride, your recovery can depend on various factors. Everyone is different, so some men will recover very quickly. For others, it can take a while and possibly require treatment. 

The side effect of persistent erectile dysfunction is rare. This is erectile dysfunction that continues for an extended period after you have stopped taking finasteride. For those who do experience this side effect, it could last months or years. However, treatment is available. 

It is important to note that men who take finasteride for a shorter period are less prone to sexual side effects like erectile dysfunction. 

Studies on both animals⁵ and human subjects showed a significant difference in the time it took to recover from erectile dysfunction caused by finasteride, based on the amount of time finasteride was taken for. However, some cases are unavoidable when taking finasteride for an extended period. 

Luckily, some factors help with erectile dysfunction treatment, possibly speeding up the recovery process. These include a good diet and regular exercise. 

How joint is erectile dysfunction with finasteride? 

Not all men who use finasteride will have side effects. In fact, only a small minority will experience erectile dysfunction. There has been some disagreement between studies on how many men report erectile dysfunction as a side-effect of finasteride, as well as whether ED is persistent in the long term in these patients. 

However, based on pooled data from many different studies, around 3-8% of men on any dose of finasteride have issues with erectile dysfunction thought to be caused by the drug. Erectile dysfunction with finasteride is much more common in men aged over 50. 

Persistent erectile dysfunction is even less common. Only around 1-2% of men, or even fewer, will experience this side effect. This side effect is also variable. In some men, this will continue for weeks to months, whereas in others, it could last a year or longer.

However, this is an active topic of research, and some researchers do not agree with the persistence of ED.

Luckily, there is a lot that can be done to help, including various lifestyle modifications that can be made and drug treatments. 

Common and severe side effects of finasteride 

Most people who take finasteride will not experience side effects. However, there are a few issues, ranging from common to rare, to look out for. Some of these are serious and require medical treatment, while others are milder. 

Side effects in men 

The most common side effects are sex-related. These side effects include: 

  • Erectile dysfunction

  • Low sex drive and disinterest in sex

  • Difficulty ejaculating

  • Reductions in sperm count

  • Gynecomastia

  • Testicular pain

Less common side effects include: 

  • Allergic reactions (tingling, itching, swollen lips, and face)

  • Depression and suicidal thoughts (most common in younger people, although it is actively debated whether it is truly an adverse effect and is currently unclear) 

Severe (rare) side effects include:  

  • Male breast cancer — however, this is debated, as several high-quality studies have failed to demonstrate an association.

  • Increased chance of higher-grade prostate cancer — this may be due to detection bias. However, there’s a decreased risk of prostate cancer overall.

It is important to note that finasteride does not increase your chance of getting prostate cancer — it actually lowers it. But studies have found that those on finasteride who get prostate cancer have a greater chance of having a higher grade (more advanced) form of cancer. 

Side effects in women 

Women are typically not prescribed finasteride except in rare cases of female pattern hair loss, i.e., androgenic alopecia.

Although the drug is well tolerated in females, there can be several side effects. These include: 

  • Possible congenital disorders if pregnant

  • Sore stomach and digestive discomfort

  • Lower sex drive 

Ways to reduce the side effects of finasteride 

If you do experience side effects of finasteride, they can significantly affect your quality of life. However, these issues can be reduced. Here are a few different strategies that could help with side effects: 

Changing your dose

If you are experiencing side effects from a high dose of finasteride (5mg), talk to your doctor about decreasing your dose. However, depending on your medical condition, this might not always be possible. Always listen to the advice of your doctor. 

Avoiding NSAIDs 

Taking NSAIDs (Advil or Motrin) can put you at risk of erectile dysfunction, without considering the effects of medications like finasteride. If you are concerned about erectile dysfunction, in any case, it is best that you avoid these over-the-counter medicines. Ask your doctor for advice on alternatives. 

It is critical that you minimize any risk factors that might predispose you to erectile dysfunction. 

Changing your lifestyle 

A lot of the side effects of finasteride can be made worse by lifestyle factors like poor diet, alcohol, and a lack of exercise. This is especially true for the sexual side effects. Try eating plenty of fruit and vegetables and reducing your saturated fat, salt, and alcohol intake. Also, regular, moderate exercise can help. 

This is important because factors like obesity are strongly linked⁶ to sexual side effects like erectile dysfunction. 

How to treat erectile dysfunction caused by finasteride 

If you are experiencing erectile dysfunction caused by finasteride, talk to your doctor. They will likely give you some general advice about diet and exercise and avoiding NSAIDs. They may also adjust your dose.

For example, if you are on 5mg, your doctor may consider a lower dose of 1mg. 

Erectile dysfunction caused by finasteride can also be treated. Usually, a drug called phosphodiesterase type 5 (PDE5) inhibitor⁷ is used. 

Examples of PDE5 inhibitors include sildenafil (Viagra) and tadalafil (Cialis). If treatment with PDE5 inhibitors is ineffective and you are experiencing persistent erectile dysfunction, other, more invasive treatments can be considered. 

These treatments include intraurethral suppositories (medications that can be inserted into the urethra) and penile injections of medications. These invasive treatments are only used in the most extreme cases of erectile dysfunction, which are very rare. 

When to visit your doctor 

If you experience any severe side effects of finasteride, like an allergic reaction, seek immediate medical attention. Serious allergic reactions can be life-threatening if not treated immediately. 

See your doctor if you are experiencing other side effects like severe depression and suicidal thoughts. Mental health symptoms can be managed. It is especially important to visit a doctor as soon as possible if you experience signs of male breast or prostate cancer. 

Signs of male breast cancer include a lump in the chest area, sore breast tissue, and nipple pain or discharge. Symptoms of prostate cancer include difficulty urinating, pain during urination, and blood in the urine. These issues are very rare, but it is important that they are caught early. 

It is best to visit your doctor if you have erectile dysfunction, whether you suspect it to be related to finasteride or not. This is because erectile dysfunction can be associated with other health issues like heart conditions or high blood pressure. Your doctor can provide advice and treatment to help with erectile dysfunction. 

It is important to remember that there are solutions to reduce many side effects of finasteride. Your doctor can help. 

The lowdown 

Finasteride is a prescription medication used to treat male-pattern baldness and prostate enlargement. Finasteride can cause several sexual side effects, including erectile dysfunction, low sex drive, and difficulty ejaculating. In terms of erectile dysfunction, this is often a temporary, short-term issue that ceases once you stop taking the drug. 

However, for some men, it can take time to recover, and treatment may be needed. This side-effect is less common in younger men and men who take the medication for a shorter period. 

Visit your doctor if you experience any of the following whiles on finasteride: 

  • Allergic reaction

  • Severe depression or suicidal thoughts

  • Signs of male breast or prostate cancer

  • Sexual problems like erectile dysfunction

  1. Finasteride and erectile dysfunction in patients with benign prostatic hyperplasia or male androgenetic alopecia (2019)

  2. Sexual side effects of 5-α-reductase inhibitors finasteride and dutasteride: A comprehensive review (2017)

  3. Adverse sexual effects of treatment with finasteride or dutasteride for male androgenetic alopecia: A systematic review and meta-analysis (2021)

  4. Recent advances in the understanding and management of erectile dysfunction (2019)

  5. Persistent erectile dysfunction after discontinuation of 5-Alpha reductase inhibitor therapy in rats depending on the duration of treatment (2019)

  6. Obesity and erectile dysfunction: From bench to clinical implication (2019)

  7. Combination of tadalafil and finasteride for improving the symptoms of benign prostatic hyperplasia: Critical appraisal and patient focus (2015)

Other sources:

Have you considered clinical trials for Erectile dysfunction?

We make it easy for you to participate in a clinical trial for Erectile dysfunction, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

Joining community groups and exercise programs for my condition made me feel empowered – but I want to be part of finding a cure.
Peter, 64

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