Finasteride: what to know before you start

What finasteride does

Your body turns some of its testosterone into a stronger hormone called DHT (dihydrotestosterone). An enzyme called 5-alpha reductase does this conversion. In people with a genetic sensitivity, DHT acts on hair follicles on the top of the scalp and slowly shrinks them.

As a follicle shrinks, its growing phase gets shorter. Each new hair comes back thinner and shorter than the one before, until some follicles make only fine, barely visible hairs. This is why pattern hair loss is gradual: a hairline recedes or a crown thins over years, not weeks. Our guide to pattern hair loss explains this in more detail.

Finasteride blocks the enzyme. Less testosterone becomes DHT, so the follicles are under less pressure to shrink. Hair that was getting thinner can stabilise, and some shrunken follicles can grow thicker hair again. It cannot restore a follicle that has stopped working altogether, which is one reason doctors often suggest starting earlier rather than later.

This is a different route from minoxidil. Minoxidil works on the hair cycle directly; finasteride works on the hormone that drives pattern hair loss. Some men use both, and the 2017 European guideline says the combination can be considered.² You can read more in our minoxidil guide.

Who it is for, and who it is not for

Finasteride 1 mg is for adult men with pattern hair loss: a receding hairline, a thinning crown, or both. The 2017 European guideline on pattern hair loss recommends it for men with mild to moderate loss. "Recommend" is its strongest level of advice.² In EU countries, finasteride 1 mg is authorised for younger adult men with early-stage pattern hair loss.³

It is not for everyone:

• Women who are pregnant or may become pregnant must not take finasteride, and should not handle crushed or broken tablets. It can affect how a male baby's genitals develop. Whole, coated tablets are not a risk to touch.
• Women in general. Finasteride 1 mg is not licensed for women's hair loss. For women after menopause, the guideline suggests not using it.² A Cochrane review found it worked no better than a placebo in female pattern hair loss, although the evidence was of low quality.⁴ For women, minoxidil has much better support.
• Children and teenagers. It is a medicine for adult men only.

It also helps to be sure what kind of hair loss you have. Sudden shedding all over the head, or round bald patches, have other causes, and finasteride will not help them. A doctor can tell the difference, often just by looking at your scalp and asking a few questions.

What to expect

The best-known evidence comes from large trials of finasteride 1 mg, with 1553 men in total.¹ The researchers counted hairs in a small circle on the crown (5.1 cm², about the size of a large coin), where the men started with about 876 hairs.

After one year, men taking finasteride had about 107 more hairs in that circle than men taking a placebo. After two years, the difference was 138 hairs.¹ Every other way the researchers measured the result also improved. Part of that difference comes from the placebo group: their hair loss kept getting worse. Note too that the hairs were counted on the crown. Results at the hairline can differ.

In plain words: finasteride mainly stops pattern hair loss from moving forward, and it can add some hair back. It does not restore a full head of hair, and results differ from man to man.

A 2022 analysis that compared hair-loss medicines in men ranked finasteride 1 mg first for thick, pigmented (terminal) hairs after 48 weeks.⁵

How long before you can tell

Finasteride is slow, because hair is slow. The 2017 European guideline advises a first check at six months, but notes that in some men the effect shows only at 12 months.² So treat six months as an early check, and twelve months as the point for a fair verdict.

123456789101112Little visible yetEarly checkFair verdict

Take photos of your hairline and crown before you start, in the same light and from the same angles. Compare them at six and twelve months. At the early check, "no worse than before" is already a good sign.

The guideline advises staying on finasteride to keep the effect.² If you stop, DHT goes back to its usual level, and over the following months your hair is likely to return to where it would have been without treatment.

If it has not helped after a year

If twelve months of daily finasteride have made no difference, talk to your doctor about what comes next. The 2017 European guideline says that a related tablet, dutasteride, can be considered at that point. It works on the same enzyme, but it is not licensed for hair loss, so using it this way is off-label and a doctor's decision.²

Finasteride also plays a part for men who choose a hair transplant. The guideline suggests combining the two.² A transplant moves hair from the back of the head to thinner areas, but it does not stop the hair around it from thinning.

Side effects

Many men take finasteride without any side effects. In the large trials, the authors described side effects as minimal.¹

The side effects men worry about most are sexual:

• lower sex drive
• difficulty getting or keeping an erection
• less semen when you ejaculate

These are reported in a small share of men. They often settle after stopping the tablets. Leaflets also mention reports of sexual problems that continued after stopping, and how often this happens is not known. If any of these worry you, talk to your doctor rather than stopping and starting on your own.

It also helps to know that sexual problems have many possible causes, including stress, tiredness and worry about your hair. A doctor can help you sort out what is likely to be behind them. Stopping finasteride is always an option, and it is a normal thing to discuss.

Since 2025, the leaflet for finasteride 1 mg tells you to get medical advice for sexual problems, because they can contribute to changes in mood.³ The next section explains why.

Other side effects are less common:

• Breast changes, such as tenderness or swelling. Tell a doctor about any breast change, including a lump or discharge from the nipple.
• Allergic reactions, such as a rash, or swelling of the lips, face or throat. Stop taking the tablets and get medical help straight away.

Mood and the 2025 EU review

In 2024, the French medicines agency asked the European Medicines Agency (EMA) to review reports of suicidal thoughts in people taking finasteride. The EMA's safety committee published its findings in May 2025.³

Here is what it concluded, in plain words:

• Suicidal thoughts are a confirmed side effect of finasteride tablets. This covers both the hair-loss dose and the higher dose used for an enlarged prostate. How often it happens is unknown. Most of the reports came from men taking finasteride for hair loss.
• The number of reports is small next to how widely it is used. The committee looked at 313 reports linked to finasteride, against about 270 million patient-years of use. One patient-year is one person taking it for one year. Because these are reports sent in by doctors and patients, they cannot give a true rate, so they cannot tell you your own risk.
• Packs now include a patient card. Packs of finasteride 1 mg tablets now come with a card about this risk.
• Dutasteride was treated with caution. There was not enough evidence of a link, but as a precaution its leaflets now mention low mood, depression and suicidal thoughts.
• The scalp spray is different. There was no evidence linking finasteride skin spray to suicidal thoughts, so its information did not change.
• The benefits still outweigh the risks for all approved uses.

The European Commission made the outcome final on 22 August 2025, so these measures apply across the EU.³

None of this means finasteride will change your mood. It means you should know the signs and act on them. Watch for low mood, losing interest or pleasure in things you usually enjoy, feeling hopeless, or thoughts of harming yourself. It can help to tell someone close to you that you have started a new medicine, so they can tell you if they notice a change.

If your mood changes, stop taking finasteride and contact a doctor.³ If you have thoughts of suicide, get help now: call 112, or your local emergency number.

How to get it

Finasteride 1 mg needs a prescription. We confirmed this in the official medicines registers for Poland and Ireland.^6,7 As far as we know, it is prescription-only across the EU, but we have not checked every country. A general practitioner or a dermatologist can prescribe it.

At the appointment, expect questions about when your hair loss started, how fast it has changed, and whether it runs in your family. The doctor will look at your scalp and may suggest blood tests if the pattern is unclear. It is a good moment to raise any worries about side effects, including mood.

Your doctor will usually prescribe a generic product. Generic tablets contain the same active substance at the same dose, and they are often cheaper than the original brand.

There is also a finasteride spray that you put on the scalp. As described above, the EMA found no evidence linking the spray to suicidal thoughts.³ The 2017 European guideline made no recommendation for or against topical finasteride.² If you are interested in the spray, ask your doctor whether it is available and suitable for you, and read finasteride spray: what we know.

Before you start

A few practical points to discuss with your doctor:

• Your history. Mention any past depression or anxiety, any liver problems, and every medicine you take.
• Prostate tests. Finasteride lowers the result of the PSA blood test, which doctors use to check the prostate. If you ever have this test, tell the doctor that you take finasteride.
• How to take it. One tablet a day, at about the same time, with or without food. Swallow it whole.
• Your timeline. Plan to take it every day for at least a year before you judge it. If you miss a tablet, skip it and take the next one as usual. Do not take two at once.
• Your photos. Take them before the first tablet, so that you have something honest to compare with later.