What are the Side Effects of Finasteride?

Written by
The Manual Team
Medically approved by
Dr Earim Chaudry
Last updated
7th January 2022

In 30 seconds…

As one of the most effective treatments for male pattern baldness, Finasteride is a popular drug for those who are experiencing hair loss. However, as for all medications, there are side effects of Finasteride to be aware of. Although it’s important to note that  98.6% of men experienced no serious side effects to the drug in clinical trials.

Possible finasteride side effects include dizziness and weakness; swelling in your hands and chest; and erectile dysfunction, decreased libido, and abnormal ejaculations. The latter, sexual side effects have received much publicity. Despite this, the evidence suggests they are rare and usually reversible.

Finasteride is a fully-licensed drug and designated safe for medical treatment – and it is the most effective drug for male pattern baldness by far.

What happens when you take Finasteride?

Finasteride is the most effective and most common treatment for male pattern baldness (MPB). Taken as a once-daily pill, it stops hereditary hair loss in nearly ninety percent of men – and reverses it in 66%

MPB is caused by the action of the hormone, dihydrotestosterone (DHT), at the follicular receptor sites in the scalp. This hormone is a product of the action of the enzyme known as 5alpha (5α) Reductase, which converts testosterone into DHT. DHT acts at these receptor sites causing the gradual miniaturization and weakening of the hair shaft – which eventually leads to thinning and fragmenting.

When you take Finasteride, the drug targets the 5α Reductase enzyme and inhibits that conversion of testosterone to DHT. As the enzyme can no longer produce the hormone, less DHT turnover allows less damage at the hair follicular site. This results in more hair. Makes sense!

But as it intervenes in a hormonal process, there can be side effects of Finasteride. Let’s take a look…

What Are the Side Effects of Finasteride?

All drugs have side effects – and Finasteride is no different. The good news is that not everyone experiences them. Given that it is licensed for medical use, the Finasteride side effects are rare. When they do occur, they are also temporary and usually mild.

In the case of Finasteride, though, lots of attention has been paid to the side effects. It’s worth cutting through the fuss to examine closer…

Finasteride and Sexual Dysfunction

The most notorious Finasteride side effects are those of a sexual nature. You may have read the reports about this one before. In the biggest news, the US Food and Drug Administration (FDA) released a caution about Finasteride back in 2012. This warned about the possibility of side effects including decreased libido and ejaculation and orgasm disorders. Alongside the suggestion that these side effects could last even after Finasteride has stopped being taken, it’s not surprising that this made the news

However, it’s the FDA’s job to be cautious – and the evidence upon which they were working was far from overwhelming. Over 23 years, the FDA received only 421 reports of sexual dysfunction following Finasteride use, with 59 cases of side effects lasting for three months after the medication was stopped. 

Whilst the FDA were right to draw attention to the possibility of these Finasteride side effects occurring, the media response was not in proportion to the figures.

So, is it true that Finasteride causes sexual dysfunction?

The evidence from the clinical trials into Finasteride puts the conversation about its sexual side effects into context. It is really quite uncommon for these side effects to occur. We’re talking about one percent.

Further, according to a study analysed by the NHS, which investigated over seventeen thousand cases, only 1.4% of men who took Finasteride had persistent erectile dysfunction after they had stopped the drug. This study included those who had taken the 5mg dose for an enlarged prostate – for whom the side effects are much more likely than in those who take the 1mg dose for MPB.

The difference between the dosages is important. Whilst the 5mg dosage has been found in a review of studies to be connected to increased risk of sexual dysfunction, for the 1mg dose there is no such correlation. In fact, the review found that there is no statistically significant connection between Finasteride for MPB treatment and these side effects. So, you can rest assured that the volume surrounding these side effects of Finasteride is more sound than substance.

Other Finasteride Side Effects

Whilst much of the hype around Finasteride’s side effects is overstated, there are some to be aware of. If you experience any of them, it is advised that you consult a clinician. 

The side effects of Finasteride include the following:

  • Chills and cold sweats,
  • Dizziness, light-headedness or confusion,
  • Tenderness or swelling around the breasts, face, hands, or feet, 
  • Rashes or redness,
  • Unusual changes of weight.

A runny or blocked nose, as well as drowsiness and abdominal pains, are also possible.

What About Finasteride and Cancer?

Finally, there was once some discussion about the possibility of Finasteride causing prostate cancer. However, this, again, has not been shown to be as certain as some of the reporting has suggested. A famous study released in 2003 showed that, whilst people taking Finasteride were 30% less likely to develop prostate cancer, they were potentially more likely to develop “high-grade” prostate cancer. 

Since this headline-grabbing study, however, there has been further research. Following up with Finasteride users after nearly twenty years, one study found that Finasteride users had a 25% lower chance of dying from prostate cancer than those who did not use the drug.

How to Reduce the Side Effects of Finasteride?

A common question doctors receive is whether it is possible to reduce the side effects of Finasteride whilst still taking the drug. Whilst you’ll see suggestions about this online, the answer is one you might not like to hear: the only way to reduce the side effects of Finasteride for sure is to… not take it. 

A healthy lifestyle – including exercise and a balanced diet – may help to improve Finasteride side effects such as reduced libido and erectile dysfunction, whilst cutting down on cigarettes and alcohol helps too. And of course, ensuring that you take the medicine as prescribed helps you avoid potential side effects.

Some newspapers have reported that the sexual dysfunction side effects of Finasteride cannot be treated with ED medications like Viagra or Sildenafil. However, there is plainly not enough evidence to support this assessment. Moreover, there are no known interactions between the two drugs, but if in doubt you can consult the Manual clinicians – this is a common query we handle on a daily basis. 

Alternatively, you could take a different hair loss medication such as Minoxidil, which is a topical product. Indeed, the two work very well together as a holistic treatment for MPB. 

Is Finasteride Safe?

So, all things considered, is Finasteride safe? The evidence says yes. Despite the possibility of side effects, Finasteride remains a medicine that is officially licensed and approved for public use – and it continues to be the best option for treatment of both MPB and an enlarged prostate. 

Whilst it is often difficult to navigate the discussions surrounding some drugs, you are right to take the time to do so. And, at the end of the day, it is your decision whether the benefits outweigh the risks. According to most medical experts, they do.

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Key Takeaways…

Finasteride has gained some notoriety for its side effects. However, these are largely overstated. Generally, Finasteride side effects are rare and, in 99% of cases, they are temporary. If you are worried about the sexual side effects of Finasteride, remember that the low dosage used for MPB makes them highly unlikely in any case. As ever, if in doubt, consult a medical expert.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Further reading

From our health centre. Experts, information and hot topics. See all Finasteride articles

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