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Finasteride 1mg: Uses, Side Effects, Interactions, Results
Dr Ahmad Moussa (FRCS)
Medically reviewed by
Dr Ahmad Moussa (FRCS)
Updated on June 11, 2024

Finasteride 1mg is a licensed hair loss treatment for tackling male pattern baldness. This popular first-line treatment is always or often recommended by 69.1% of hair restoration surgeons [1].

In this article, you’ll learn all about Finasteride 1mg, including:

  • How it works to slow hair loss and promote hair regrowth.
  • How much Finasteride 1mg you need to take to effectively treat male pattern baldness
  • The side effects of Finasteride 1mg.
Table of Contents

What is Finasteride 1mg and what does it do?

Finasteride (also known as generic Propecia) is a drug that reduces the activity of the 5-alpha reductase enzyme in your body. 5-alpha reductase converts testosterone to dihydrotestosterone (DHT), a hormone that’s essential for male physical development in early life.

However, in adulthood, DHT is a major factor in the development of male pattern hair loss and prostate enlargement. DHT binds to androgen receptors in the hair follicles, causing them to shrink. As a result, these miniaturised hair follicles eventually stop producing hair.

By inhibiting 5-alpha reductase, Finasteride reduces DHT production to minimise its effects on your hair and body.

finasteride chemical structure

How much DHT does 1mg Finasteride block?

Finasteride 1mg can reduce scalp DHT levels by as much as 64% [2]. It can also reduce serum DHT levels — the amount of DHT in your body as a whole — by 71%.

Finasteride 5mg, the higher dose of Finasteride used to treat benign prostate enlargement, can reduce DHT levels by slightly more (69% and 72% respectively). However, researchers agree that this difference isn’t enough to recommend 5mg of Finasteride for the treatment of hair loss in most cases.

Does 1mg of Finasteride work to treat hair loss?

Yes. Multiple studies have shown that Finasteride 1mg is an effective dose for treating male pattern baldness [2-5].

A long-term study found 85.7% of 126 male Korean patients achieved improvements in their hair loss over five years [5]. Bald spots on the crown showed the most improvement, followed by frontal balding around the hairline.

It doesn’t take five years to see good results from using Finasteride 1mg. Studies show that Finasteride can slow hair loss in as little as six months [3].

It should be noted however, that Finasteride treatment for hair loss works best for men with mild to moderate hair loss, not complete hair loss.

Does Finasteride 1mg regrow hair?

Yes, as well as stopping further hair loss, Finasteride 1mg can actually help your hair regrow.

The chances of mild to moderate visible hair regrowth are 61% on the crown and 37% on the frontal hairline after a year of using 1mg of Finasteride [2].

One study found that Finasteride 1mg treatment led to an 11% increase in hair count in men with crown hair loss after a year, which was maintained after two years [2].

before and 6 months after patient taking Finasteride for hair growth
before and after results of patient taking Finasteride for 1 month
Improved hair growth in two patients before and after six months of taking Finasteride 1mg [3].

Is it OK to take 1mg Finasteride for hair loss?

Yes. 1mg of Finasteride is the licensed dose for treating male pattern hair loss, so this is often the first treatment recommended by trichologists (alongside Minoxidil).

Is 1mg of Finasteride a day too much?

For most men, 1mg of Finasteride a day is the appropriate dose. But if you’re concerned about taking too much Finasteride, speak to your doctor about your dosage. They may be able to recommend alternative hair loss treatments.

How long should I take Finasteride 1mg for hair loss?

You need to take Finasteride 1mg for at least three to four months before your hair loss starts to slow. Further improvements should be visible after around six or seven months of continuous daily use.

You’ll need to take 1mg of Finasteride continuously to maintain the hair you’ve regrown. If you stop taking Finasteride, you may find your hair starts to shed again after a few months.

Is 1mg Finasteride safe?

Finasteride 1mg is generally a safe drug to take on a daily basis. But there are some side effects to be aware of, and some instances where you’re advised to avoid Finasteride.

Exposure to Finasteride in pregnancy can interfere with a baby’s development. For this reason, premenopausal women are generally advised to avoid using Finasteride. Pregnant women are also advised not to handle broken or crushed Finasteride 1mg tablets.

In addition, there are some concerns about the impact of Finasteride on fertility and sexual performance. Up to 3.8% of Finasteride users may see adverse sexual side effects like erectile dysfunction and low libido [6].

Finasteride has also been linked with low sperm count and reduced sperm motility, but these effects are temporary, and will reverse if you stop taking Finasteride [6]. So it’s important to discuss your Finasteride usage with a doctor if you’re planning to try for a baby in the near future.

What are the side effects of Finasteride 1mg?

Reported side effects of Finasteride 1mg include:

  • Finasteride shedding
  • Erectile dysfunction
  • Decreased sex drive
  • Ejaculation disorder
  • Testicular discomfort
  • Skin rashes

Most of these side effects only impact a small number of users. If you’re worried, speak to your doctor or trichologist for advice.

Topical Finasteride may be a good alternative for those who are concerned about side effects. While topical Finasteride hasn’t yet been licensed for use, studies show promising results for people with hereditary hair loss. Find out more about how to effectively reduce the side effects of Finasteride. 

Finasteride 1mg drug interactions

Finasteride may interact with other drugs, so consult with your GP before using Finasteride if you’re taking any of the following:

  • 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. If you’re taking any medication, check with your doctor if Finasteride is safe for you to use. Your doctor may decide to monitor you to make sure there are no interactions over time.

Can women take Finasteride 1mg?

Finasteride 1mg is effective for tackling female pattern hair loss [7]. However, women should be cautious when taking Finasteride due to possible side effects and complications.

As well as causing complications in pregnancy, Finasteride can lead to changes in the menstrual cycle [7]. So premenopausal and perimenopausal women are normally advised to avoid taking Finasteride.

The best way to tackle hair loss in women is to get a diagnosis from a qualified trichologist. This can help you find the best female hair loss treatment plan.

How to take Finasteride 1mg

Take Finasteride as advised by your doctor or trichologist. For most people, this is one 1mg tablet each day, swallowed with a glass of water. If you forget to take your Finasteride, simply skip the missed dose and continue taking Finasteride at your normal routine time. Do not double your dosage.

If you reduce your Finasteride intake to three times a week, you could reduce the effectiveness of the drug.

Learn more about whether you should take Finasteride in the morning or at night.

Can you cut a 1mg Finasteride tablet in half?

It’s best not to cut your Finasteride tablets in half unless advised to do so by your doctor or trichologist. Reducing the dose will impact the effectiveness of the drug.

Should you take 1mg of Finasteride for hair loss?

Should you take 1mg of Finasteride for hair loss?

If you’re experiencing male pattern baldness, including a receding hairline, Finasteride is one of the most effective non-surgical treatments. So unless you’re concerned about side effects, or advised not to take Finasteride, it’s a great way to reduce hair loss and even stimulate hair growth.

If you’re still weighing up your hair loss treatment options, book a consultation with our hair loss specialists. We can help you decide if Finasteride is right for you, and discuss alternative treatments with you.

Finasteride 1mg: Uses, Side Effects, Interactions, Results, Wimpole Clinic

Finasteride 1mg FAQs

Find out more about Finasteride 1mg in these frequently asked questions.

Some studies have linked Finasteride with erectile dysfunction [6, 8]. However, this impacts a very small number of Finasteride users.

One study found that 1.4% of Finasteride users experienced erectile dysfunction after a year of use, decreasing to 0.7% after two years and 0.3% after four years [8].

Some evidence suggests a 1mg dose of Finasteride each day can impact male fertility, especially if you’re already prone to fertility problems [9].

Most patients with Finasteride-related infertility find that their sperm count and motility return to normal levels a few months after stopping Finasteride. So if you’re thinking about trying to conceive, speak to your hair loss consultant and GP about the best course of action for your hair loss.

Yes, 1mg Finasteride can shrink your prostate. While Finasteride 5mg is usually the standard dose for treating an enlarged prostate, treatment with 1mg Finasteride may reduce prostate volume by up to 18% [10].

Speak to your GP to find out which dose is most suitable for you.

Taking 1mg of Finasteride each day is very unlikely to cause cancer. Just three UK cases of male breast cancer have been reported with the use of 1mg Finasteride in the last ten years [11].

By comparison, 50 cases have been reported in the same period among men taking a 5mg dose daily. So the risk is slightly higher with a 5mg dose of Finasteride.

However, it’s important to note that these numbers are extremely small in comparison with the overall number of Finasteride users. So the chances of developing cancer as a result of using Finasteride are very slim.

It can take up to eight hours for the amount of Finasteride in the body to reduce by half [12].

As a result, it can take up to 56 hours (2-3 days) for the amount of Finasteride in your system to reduce to less than 0.01 mg.

Finasteride builds up in the body after you’ve been taking it for a while. So it may take longer to leave your system if you’ve been using it for a few months or more.

1mg of Finasteride costs between £12.20 (a month) and £58.80 (4 months) per prescription, depending on your dosage, amount, and pharmacy.

Finasteride 1mg is a prescription drug, so you’ll need to get it from a doctor or trichologist. Speaking to a qualified trichologist is the best way to find out if 1mg of Finasteride is the right treatment option for your hair loss.

Dr Ahmad Moussa (FRCS)
Medically reviewed by Dr Ahmad Moussa (FRCS)Updated on June 11, 2024
The Wimpole Clinic offers FUE Hair, Beard & Eyebrow Transplants & Trichology.
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