August 01, 2020

The side effects of Finasteride [What are they not telling you?] Part 1

To watch our vlog please press play below: 👇🏽

Hi guys,

For our regular Q&A one of our Instagram followers 

(@itreallyworksvitamins(send in any questions you have btw)

We were asked about the side effects of Finasteride.

I wanted to share some important information that on one hand helps to dispel some of the possible scaremongering out there.

I want to go through some of the headlines, and the research studies, - unpick exactly what’s been said, and look at exactly how these research studies have been carried out and consider the potential issues with them.  

I also want to highlight that for 1 in 20 men who take Finasteride, there are some potentially long-term or permanent side effects. 

Research into the long-term side effects of Finasteride is still ongoing. 

Finasteride side effects

A 2014 review in Korean Journal of Urology found at least four previous studies that reported “persistent or irreversible” sexual side effects.

The authors said the studies reported “negative emotional toll and reduced quality of life” for the men affected.

“The argument that the benefits of these drugs outweigh the risks is slowly eroding in the face of new emerging scientific evidence from preclinical and clinical studies,” the authors wrote.

Men who suffered long-term sexual dysfunction after taking Propecia have filedlawsuits against Merck that accuse the company of failing to warn users of the risk.

Just in the U.S, 5 million men were prescribed Finasteride in 2007, that figure doubled to over 10 million men by 2016.

Finasteride number of prescriptions over time (2007-2017)

Finasteride is an extremely commonly prescribed medication. In the US between 2007 and 2017 over 76 million men were prescribed Finasteride,

Just in The US alone, if 5% are affected by adverse side effects, that makes 3.81 million men over the course of ten years experiencing some degree of side effects. 

Out of this it’s unclear how many people will experience long term side effects once they stop taking the drug.

I’ll be looking at the potential for sexual side effects including:

  • Loss of libido
  • Impotence
  • Ejaculatory Disorders
  • Depression and Thoughts of Suicide, in people who had previously not experienced these.

Side effects of Finasteride

It’s vital to ask your haircare doctor about the rate of side effects that their patients experience after being prescribed Finasteride.

Towards the end of the video I share some interesting information on dosage of Finasteride and how this could potentially help to reduce these side effects.

So please do watch all the way through.

So let’s get straight into it.


Finasteride is a prescription-only tablet taken orally and it was approved by the FDA in 1992 for the treatment of enlarged prostates. 

Finasteride is the generic form of the drugPropecia. WhilePropecia is the more well-known and recognised name, they do the same thing and provide the same overall benefits. 

Propecia is the most often prescribed medication for male pattern baldness.

Finasteride helps to shrink enlarged prostates, and in doing so, helps to reduce the risk of acute urinary retention or the need for surgical procedures.

When testing Finasteride, researchers discovered that one of the interesting, accidental side effects was that balding men began to regrow their hair. 

And so it was 6 years later that Finastiride came onto the market as a drug that can reverse hair loss.

Finasteride is often described as a DHT blocker - but it doesn’t actually block DHT - it blocks the enzyme 5 Alpha Reductase.

This enzyme is responsible for converting Testosterone to DHT.

So let’s have a really quick recap on what DHT actually is:

DHT stands forDihydrotestosterone.

Dihydrotestosterone and Finasteride

It’s a hormone produced in the skin, liver and testes.

DHT is present in both men and women, but DHT related hairloss, otherwise known Androgenic Alopecia or pattern baldness affects much more men than women

“By the age of thirty-five two-thirds of American men will experience some degree of appreciable hair loss”

The American Hair Loss Association:

In genetically pre-disposed guys an enzyme called 5-Alpha Reductase combines with testosterone to snythesize DHT. 

5 Alpha Reductase

When flowing around your blood stream DHT attaches itself to genetically susceptible hair follicles and shrinks them.

 Basically this is calledminiturisation. And it gradually  kills the hair follicle so that hair no longer grows there.

The formation of excess DHT can be stopped

Finasteride acts as a specific inhibitor of Type II 5α-reductase.

Treatment with Finasteride may have some effect on type I 5α-reductase, which is predominantly expressed in sebaceous glands of most regions of skin, including the scalp, and liver. 

It is proposed that the type I 5α-reductase and type II 5α-reductase are responsible for the production of one-third and two-thirds of circulating DHT, respectively.

Lowering the body’s levels of DHT may correct hair loss, but problems arise because the sex hormone is also important for maintaining:

  • the structural integrity of nerves, 
  • smooth muscle, 
  • connective tissue 
  • and signaling pathways in the penis.

Finasteride has been around for almost 30 years, extensive testing has been done on this drug and it’s largely considered safe and effective in treating hair loss. 

But I also want to highlight that for 1 in 20 people will experience some side effects.

The most common of which include:

Impotence, loss of interest in sex, trouble having anorgasm, abnormalejaculation, swelling in your hands or feet, swelling or tenderness in your breasts, dizziness,weakness, feeling like you might pass out, headache,runny nose, orskin rash.

In some men, finasteride may decrease the amount of semen released during sex. 

side effects Finasteride

This is a harmless side effect but has continued in some men even after they’ve stopped taking finasteride. 

This may become more of a concern for you if you want to start a family.

If this happens to you, it’s important to tell your doctor immediately if the side effects get worse or persist.

It’s also important to tell your doctor immediately if you have any of the serious side effects:

  • nipple discharge,
  • lump in the breast,
  • breast enlargement or tenderness,
  • pain in the testicles, and
  • inability to urinate.

An allergic reaction to finasteride is not likely, but get immediate medical attention if they occur. The symptoms of a serious allergic reaction include itching or swelling, especially of the face/tongue/throat, rash, trouble breathing, and severe dizziness.

The sexual side effects of Propecia may continue after you stop taking it. It’s always important to talk to your doctor if you have concerns about these side effects. 

Propecia may also cause decrease in bloodprostate specific antigen (PSA) levels, and can affect the PSA blood test.

It’s extremely important that women who are, or may be pregnant do not touch the Finasteride tablet, as it can cause birth defects. The exposure of a male fetus to finasteride may result in the development of abnormal genitals.

It should also not be handled by a breastfeeding woman. 

Propecia is available in strength of 1 mg tablets; the recommended dose of Propecia is one tablet (1mg) taken once daily. 

Apparently, President Trump has taken Propecia for many years:

Trump and Finasteride

In general, daily use for three months is necessary before hair growth is observed. 

Stopping treatment can lead to reversal of the hair that’s grown within 12 months.

Propecia may interact with other drugs and so don’t forget to tell your doctor all medications and supplements you use.

Before using this medication, also be mindful to tell your doctor your medical history, especially of;

  • prostate cancer,
  • liver disease, 
  • infections, 
  • and urinary problems.

The vast majority of men who experience side effects from finasteride also notice these side effects stop when they stop using the medication, 

In general, I feel that it’s important to reiterate that the side effects are rare

In this study:

In the authors’ opinion, the most informative trial specifically analyzing the effect of finasteride and sexual functioning was the Prostate Cancer Prevention Trial.

This was a randomized, double-blind, placebo-controlled study that was able to evaluate sexual dysfunction and any possible confounding variables in 17,313 participants over seven years. 

They utilized a sexual activity scale, ranging from 0 to 100 with higher numbers demonstrating greater sexual dysfunction.

The scale evaluated the ability to have an erection, the degree of sexual satisfaction, any change in sexual performance, and frequency of sexual activities. 

Finasteride side effects - It Really Works Vitamins

So at whatever level the participants set their own personal level of sexual disfunction between 0-100 -

Researchers found that Finasteride this level of sexual disfunction by around 3.21 %

This decreased to 2.11 at seven years. 

Interestingly, the researchers found that other health factors in the participant’s health also leads to a similar effect of sexual dysfunction as finasteride, including

  • declining physical function,
  • increased body mass index. 
  • diabetes, 
  • hypertension, 
  • smoking, and 

Age, also worsened sexual dysfunction than finasteride, with an increase of 1.26 points per year on the sexual activity scale. 

Interestingly, the mental health score did not significantly affect sexual dysfunction over time. 

None of the 17,313 participants reported persistent sexual dysfunction. 

The authors concluded that the effect of finasteride on sexual functioning was minimal and that it should not interfere with prescribing practices.15

However there have been reports that a very small number of men continue to experience side effects after they stop taking the medication. 

It’s also important to remember that the area of research regarding finasteride’s side effects is ongoing.

One of the questions we’ve been asked on Instagram is: 

Should I worry about all the finasteride side effect reports?

To watch a video we've created on this, please click play below 👇🏽

In April 2012, the FDA issued a warning on finasteride. It stated that sexual side effects could persist even after stopping the medication. 

Those side effects include decreased sex drive and ejaculation problems. 

Ejaculatory Disorder

Propecia use also has been associated with several ejaculatory disorders. Ejaculatory disorders range from premature (rapid) ejaculation to delayed ejaculation to a complete inability to ejaculate.

A 2002 review of randomized finasteride trials found more men who took the drug reported ejaculation disorder than did men who took a placebo. 

finasteride side effects ejaculatory disorder


The research article in BMC Urology looked at five double-blind, placebo-controlled trials lasting 12 months.

The authors calculated the relative risk for ejaculation disorder was 3.6 percent for men taking finasteride.

Meanwhile, the 2003 review in the International Journal of Impotence Research found between 2.1 and 7.7 percent of men taking the drug in studies reported ejaculatory disorders.

Ejaculatory disorders associated with Propecia use include:

  • Retrograde ejaculation (when semen goes backward into the bladder rather than forward out of the penis)
  • Ejaculation failure
  • Decrease in semen volume 

The FDA warning was based on about 100 reports the FDA received over nearly 20 years. 

Propecia Sexual Side Effects

This is also not proof that finasteride was to blame, since a variety of medical conditions, including increased:

  •  Body Mass Index,
  •  Diabetes
  • Or other prescription drugs

could explain the sexual symptoms the men reported while taking finasteride.

Irreversible sexual side effects from finasteride are relatively rare, since millions of men have taken these medications during the time period surveyed. 

In March 2017, a Northwestern Medicine study found that some men who took finasteride suffered persistent erectile dysfunction in which they were not able to have normal erections for months or years after stopping the medication.

Out of 11,909 men who took finasteride or dutasteride, 1.4 percent developed persistent erectile dysfunction that continued for an average of about 1,350 days after stopping treatment, according to the study. 

There seems to be a correlation between how long you’re taking the drug for, and the likelihood of experiencing persistent erectile dysfunction.

Finasteride Sexual Side Effects

Young men who had more than 205 days of exposure to the drug had nearly five times higher risk of persistent erectile dysfunction than men with shorter exposure.

In other well-conducted research trials, sexual side effects occurred in about 4% to 6% of men, and these effects were usually reversible.

But there still have been some attention grabbing headlines which have really put people off taking Finasteride.

Finasteride, a hair-loss medication reportedly used by footballer Wayne Rooney, 'could cause permanent impotence and shrink genitals in some men'


Finasteride Sexual Side Effects

The story is based on two news sources. The first is a US TV interview with this person, Kevin Malley who claimed his genitals shrunk after taking Propecia.

Finasteride Side Effects

The second, more verifiable source, is a study that found that finasteride could cause persistent loss of libido and erectile dysfunction.

There are a number of significant issues with both sources.

Primarily, there doesn’t seem to be any independent background evidence supporting the claims of the man who was interviewed.

The second study included only a relatively small sample of men. 54 men were interviewed, and 44 were later re-interviewed to see if their symptoms had persisted. 

All of the people who’d been recruited into the study, were experiencing persistent sexual problems, and they were found via a website that was set up by men who claimed that finasteride had caused them sexual side effects.

This might not necessarily reflect the experiences of all men who take finasteride.

The study also fails to show the proportion of men using Finasteride, against the proportion of men who experience side effects, and from those men, how many experience permanent side effects?

Where did the story come from?

A single author from The George Washington University, US, conducted this research. From what I can tell, it’s very difficult to find out who funded this research, so it’s not clear whether there could be any potential conflicts of interest.

The study was published in thepeer-reviewed Journal of Sexual Medicine.

What can be agreed upon is this comment by:

Dr Irwig said roughly 5 per cent of men who take medicine will experience sexual dysfunction, and of those 'it’s hard to tell how many will experience persistent symptoms'.

'We know that this is a potential problem, but we can’t quantify what the exact risk is. I can’t tell a man if he has a 1-in-100 chance, or a 1-in-1000 chance of developing persistent sexual dysfunction, but it’s pretty clear there’s a relationship here,' he says.

How can you avoid the side effects of Finasteride?

There has been some discussion online that it’s not necessary to take 1mg of Propecia per day

Dr Vikram Jayaprakash and Dr Russell Knudsen highlight that Finasteride can stay in the skin for up to thirty days, and the doctors advise to take 1 mg, 3 times per week, which is enough to mop up 5 Alpha Reductase without causing any side effects.

If you do experience side effects, your doctor is likely to lower your dosage.

Dosage Finasteride

More worrying is this investigation by Reuters.

Five years before the FDA approved Propecia to treat male pattern baldness, researchers linked doses of finasteride to sexual side effects. According to a 1992 report in the New England Journal of Medicine, researchers found a higher incidence of impotence, ejaculatory disorders and decreased libido in finasteride users when compared with men who took a placebo.

The study was published just four months after the FDA approved finasteride under the brand name Proscar to treat enlarged prostates. The side effects weren’t given much thought because most of the men in studies were older with enlarged prostates, making them more prone to underlying sexual dysfunction.

Propecia Sexual Side Effects

But when Merck introduced Propecia as a hair-loss treatment in 1997, younger men — who were much less likely to have sexual dysfunction — began taking finasteride and concern of potential sexual side effects grew.

Following the early drug trials, both Merck and the FDA assured men that the sexual complications would resolve once they stopped taking the drug, but later evidence would prove the contrary.

The preapproval trials were not especially reliable, as the information was drawn from a relatively small patient group treated for only six months to one year, and follow-up procedures were unclear.

More recent investigations show the drug’s sexual side effects can persist even after a man stops taking the drug although it is still unclear, out of the 5% experiencing side effects, how many people will face permanent effects.


A July 2015 study in Pharmacotherapy also found increased risk of suicidal thoughts among men taking the medication. In this study, researchers relied on adverse events reported to the FDA. They looked at reports filed between 1998 and 2013 and narrowed the field to reports involving 18- to 45- year-old men.

Researchers looked for men who used low-dose finasteride and reported both sexual dysfunction and suicidal ideation. Out of 4,910 reports, they found 577 patients who reported persistent sexual side effects and 39 men who reported suicidal thoughts.

Of the 39 who reported suicidal thoughts, 87.2 percent also reported sexual dysfunction. Six of the sexual dysfunction reports included patient deaths.

There are more than 1,100 lawsuits filed across the United States accusing Merck of not adequately warning patients of the drug’s possible side effects and their duration. 

Leave a comment

Comments will be approved before showing up.