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The truth about Finasteride

The truth about Finasteride
13 December 2019
5-minute read

"So, I looked up Finasteride on Google and I get all sorts of results and I don’t know what to believe..."

With conflicting information circulating around the internet, it can be confusing for new patients to get to grips with information on Finasteride and its potential side effects. Studies have shown that the drug has an impressive 66% success rate in reversing male pattern baldness after just two years. However, like most drugs, some men may experience side effects from Finasteride and it’s important to be aware of these before you make a decision on whether you would like to take it or not.

How does it work?

Finasteride works by blocking the conversion of testosterone into the hormone dihydrotestosterone (DHT for short), which causes miniaturisation of hair follicles and, eventually, hair loss. This conversion is a result of the action of an enzyme known as 5 alpha (5α) Reductase, which is genetically inherited. 

Finasteride works by disrupting this conversion process by targeting the 5α Reductase enzyme and stopping the production of DHT. As DHT is one of the major reasons for hair follicle damage, Finasteride can have a remarkable effect on male balding. The end result? Less DHT, more hair!

What are Finasteride side effects?

While there is a lot of conflicting information online and it can be hard to tell the facts from the unfounded, like with any medication there are still some things to be aware of. Finasteride side effects are both rare and usually reversible, so you should feel confident when you start your treatment plan.

Like all medication, it is important that you read the accompanying patient information leaflet (PIL) prior to taking it and satisfy yourself that you understand the potential risk of taking that medication.

The most common Finasteride side effects are:

  • Reduced libido
  • Lower quantity of ejaculation

These side effects happen in less than 5% of men who take Finasteride and usually resolve on stopping. There have also been reports of erectile dysfunction among some patients. However, a study published in the British Medical Journal in 2016 showed that Finasteride does not statistically significantly increase the risk of erectile dysfunction versus placebo, whether Finasteride was taken as a 1mg dose for hair loss or a 5mg dose used in men with Benign Prostatic Hypertrophy.

There have been some reports of cases of Finasteride being associated with an increased risk of prostate cancer. Fortunately, this claim has been consistently disproved by a variety of studies and, in some cases, Finasteride has been shown to decrease the chances of developing prostate cancer by up to 25%. In terms of screening for prostate cancer, Finasteride can lower the Prostate Specific Antigen blood test, making it falsely reassuring - so it is advised to let your GP know that you are taking Finasteride, and they will usually halve the age-adjusted reference range when screening for prostate cancer to account for this. 

There have also been reports of mood alteration and depressive side effects of Finasteride which could possibly persist after stopping the medication. Whilst a direct causal link has not been proven linking Finasteride with depression, out of an abundance of caution Sons do not prescribe Finasteride to those with untreated or moderate to severe anxiety or depression.

A full list of potential side effects can be found in the Sons patient information leaflet here.

The majority of evidence concludes that any side effects associated with Finasteride happen in the first six months of use and are in most cases reversible once the medication has stopped being administered. 

Can I reduce the risk of Finasteride side effects?

So - is it possible to reduce the likelihood of getting side effects? Well, not really. We advise all our patients to lead a healthy lifestyle, eat plenty of fruit and veg, exercise regularly and cut out bad habits (eg smoking and alcohol). While we can’t mitigate against the risks of getting side effects from Finasteride entirely, it is reassuring to know that they are very rare. 

It’s also crucial to follow the recommendations of your treatment plan. Taking an excessive amount in a short period of time will have a detrimental effect on your treatment plan and may lead to a higher chance of experiencing the side effects. Keep by our routine and you’ll not only reduce the risk, but maximise the effectiveness of Finasteride.

Finally, the evidence for Finasteride causing erectile dysfunction is very thin, but some have claimed that drugs such as viagra cannot be used alongside Finasteride. It’s clear that there is not enough evidence for these claims, with no clear proof for an interaction between the two. If you are unsure about this and want to find out more, we would suggest discussing this with your GP.

Why should I use this treatment?

Finasteride has been used as a treatment for male pattern baldness for over 20 years and is the most effective prescription treatment for male pattern hair loss. There are plenty of significant medical journals that capture data from thousands of patients worldwide and testify to Finasteride’s efficacy and safety. 

Millions of people around the world take Finasteride on a daily basis, over 1 million of which are estimated to be taking it for hair loss in the United States alone. Despite the rare side effects of Finasteride, it is still the most effective medication at slowing male pattern hair loss and is effective in up to 90% of men who take it.

The evidence suggests that overall Finasteride is a very safe and effective drug. Side effects are rare, but not impossible. We advise all of our patients to familiarise themselves with potential risks and benefits of taking any new medication found in the patient information leaflet and to check with their primary care physician or GP about whether they are safe to take with any current medication.

The medical team at Sons are more than happy to discuss questions or queries you may have about Finasteride or any of our treatment options. If you’re keen to treat your hair loss, our treatment plans also contain Minoxidil, Biotin and DHT-blocking shampoo to help you regain control of your hair growth. Ultimately, only you can decide whether Finasteride is the right medication for you - our aim is to present the facts and help you make an informed decision.


The content provided in this article is not a substitute for professional medical diagnosis or treatment. You should not rely upon the information provided in this article for specific medical advice. Prior to starting any medication you should consult with your primary care provider if you are on any other medication to ensure that it is safe to do so and read the patient information leaflet, paying particular attention to potential side effects.  If you have any questions or concerns, please talk to your doctor.

All of our blog articles are reviewed by our Medical Director before publication.