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Finasteride 5mg: Uses, Side Effects, Interactions, Results
Dr Kieran Dayah (GMC)
Medically reviewed by
Dr Kieran Dayah (GMC)
Updated on May 9, 2024

Finasteride 5mg is a drug primarily used to treat benign prostate enlargement (BPE). It can also be used to treat male pattern baldness, although it’s less commonly used than Finasteride 1mg.

In this article, learn all you need to know about the Finasteride 5mg dose, including:

  • What Finasteride 5mg is used for.
  • How Finasteride 5mg works and how long it takes to kick in.
  • The side effects of Finasteride 5mg.
Table of Contents

What is Finasteride?

Finasteride is a drug that blocks the production of dihydrotestosterone (DHT), a male sex hormone metabolised from testosterone.

DHT is an important androgen for male development in early life. But for adults, high levels of DHT are linked with male pattern baldness and benign prostate enlargement (BPE) [1]. So Finasteride is often used to treat these conditions.

What is Finasteride 5mg used for?

Finasteride 5mg is the highest dose of this medicine usually administered. It’s commonly used to treat benign prostate enlargement (also known as benign prostate hyperplasia).

Benign prostate enlargement is the medical term for an enlarged prostate. It’s not usually a serious condition, but it can cause uncomfortable symptoms, such as a frequent need to urinate and difficulty urinating. That’s because prostate enlargement narrows the urethra:

Informational graphic comparing and contrasting a normal prostate gland vs an enlarged prostate gland
Image source: NHS

Finasteride 5mg is available under the brand name Proscar. It’s also available as a generic medication, which may be cheaper and works the same way. Learn more about how much Finasteride costs.

Can I use Finasteride 5mg for hair loss?

In rare cases, Finasteride 5mg can be used to treat male pattern baldness (also known as androgenetic alopecia). 

However, most evidence shows that Finasteride 5mg is no more effective at treating hair loss than Finasteride 1mg, which is the standard dose for male pattern baldness treatment [2-4]. So it’s not usually necessary to take Finasteride 5mg for hair loss.

Finasteride 5mg isn’t licensed to treat hair loss in the UK, but some doctors may prescribe it off-label.

What does 5mg of Finasteride do?

Finasteride 5mg tablets stop your body from converting testosterone to DHT by reducing the activity of an enzyme called 5-alpha reductase. Reducing your DHT levels can help shrink an enlarged prostate and reverse hair loss caused by male pattern baldness.

Finasteride chemical structure

One study found that 5mg of Finasteride reduced scalp DHT levels by 69% and serum DHT levels (i.e. DHT in the body) by 72% [2]. 

By comparison, Finasteride 1mg reduced scalp DHT levels by 64% and serum DHT levels by 71%. This suggests that in general, a Finasteride 1mg dose is enough to decrease DHT levels and slow hair loss.

How long does Finasteride 5mg take to work?

According to the NHS, it can take around six months for Finasteride 5mg to work for BPE [5].

For hair loss, you can usually see results in around three to six months.

How to take Finasteride 5mg

Take your Finasteride dose as prescribed by your doctor or pharmacist. This usually involves swallowing one tablet whole at the same time each day. Finasteride can be taken in the morning or at night just as long as it is consistently taken.

If you forget to take Finasteride one day, wait until the next day to take your next dose. Don’t double up to make up for the lost dose.

Side effects of Finasteride 5mg

Finasteride 5mg may cause side effects including:

The majority of these side effects are rare, affecting just a small number of users. But it is more common to experience these when taking a 5mg dose than a 1mg dose [6]. That’s why those with male pattern hair loss are generally advised to stick to the lower dose of Finasteride.

Does Finasteride 5mg cause weight gain?

Weight gain is not a common side effect of Finasteride.

One study has linked Finasteride with weight gain in men with prostate cancer [7]. But there’s no evidence to suggest it can lead to an increase in weight in men with BPE or male pattern baldness.

What are the long-term effects of Finasteride 5mg?

Long-term side effects of Finasteride 5mg are uncommon but may include erectile dysfunction, lower libido, and Finasteride-related gynecomastia (enlarged breast tissue in men).

Some men may also experience post-Finasteride syndrome, which is characterised by persistent symptoms even after you stop taking the medication.

Taking Viagra and Finasteride together may help if you’re experiencing issues with sexual performance.

Drug interactions with Finasteride 5mg

Some other medications are known to interact with Finasteride, so it’s important to speak to your doctor if you’re taking any of the following medicines [8]:

  • Topical Abametapir
  • Adagrasib
  • Avacopan
  • Diltiazem
  • Duvelisib
  • Fluconazole
  • Fluvoxamine
  • Fostamatinib
  • Itraconazole
  • Larotrectinib
  • Lenacapavir
  • Nefazodone
  • Nelfinavir
  • Olutasidenib
  • Omaveloxolone
  • Osilodrostat
  • Pirtobrutinib
  • Pralsetinib
  • Ritlecitinib
  • Saquinavir
  • Selpercatinib
  • Sirolimus
  • Tacrolimus
  • Temsirolimus
  • Terazosin
  • Trofinetide
  • Voriconazole

This list is not exhaustive, so if you’re taking any other medications, consult your doctor to check it’s safe to take with Finasteride. They may want to monitor you while you take the drug to ensure no interactions develop over time.

Should you take 5mg of Finasteride for hair loss?

Finasteride 5mg has been shown to effectively treat male pattern baldness. However, for most men, it’s not necessary to take a 5mg dose of Finasteride for hair loss.

Taking a higher dose can increase the risk of side effects, without offering a significantly higher chance of hair regrowth. So unless advised otherwise by a qualified trichologist, it’s best to stick with a 1mg Finasteride dose.

Not sure if Finasteride is right for you? Book a free consultation with our patient advisors. We can talk you through all your treatment options, including Finasteride alternatives such as Minoxidil and hair transplantation.

Finasteride 5mg: Uses, Side Effects, Interactions, Results, Wimpole Clinic

Finasteride 5mg FAQs

Learn more about Finasteride 5mg in these frequently asked questions.

There’s no time of day that’s best to take Finasteride 5mg tablets, but you should aim to take it around the same time each day.

Swallow the tablet whole with water. You can take Finasteride with or without food.

No. Breaking or cutting Finasteride tablets can impact the drug’s effectiveness, so you shouldn’t halve your dose.

If you don’t feel 5mg is the right dose for you, speak to your doctor about switching to a lower-strength tablet.

Finasteride for women isn’t usually advised, especially for premenopausal women. While it can be effective for tackling female pattern hair loss, it can cause complications in pregnancy and lead to irregularities in the menstrual cycle [9].

As with men, taking a 5mg dose is more likely to lead to adverse effects than a lower dose.

Yes, taking Finasteride 5mg can increase your testosterone levels. Because less testosterone is converted to DHT, testosterone levels remain higher.

However, testosterone is generally a weaker androgen than DHT. Most of the physiological effects of testosterone are mediated by its active metabolites like DHT. So even though Finasteride increases testosterone, the fact that it lowers DHT means that you’re more likely to see an anti-androgenic effect.

Dr Kieran Dayah (GMC)
Medically reviewed by Dr Kieran Dayah (GMC)Updated on May 9, 2024
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