Finasteride side effects: an honest guide before you start
Finasteride helps many men, but it also has side effects you should know about beforehand. This guide explains how it works, what results to expect, what the 2025 EMA review found and how to report problems.
Finasteride side effects: most men have no problems with it, but a minority report mood changes, including low mood and suicidal thoughts, and sexual problems such as reduced sex drive. If your mood changes, stop taking finasteride and speak to a doctor. Our doctors will go through the risks, your history and your options with you on a video consultation, without any pressure.
Causes
Why does hair thin in the first place?
Is your hairline receding or your crown thinning? You are not alone. Male pattern hair loss is common, and for many men it starts as early as their twenties. It is not a medical emergency, but it can knock your confidence, and it is perfectly reasonable to want to do something about it.
Usually two things are behind it: genes and the hormone DHT (dihydrotestosterone). If your hair follicles are genetically sensitive, DHT gradually shrinks them. Each new hair grows a little thinner and shorter than the one before, until the follicle eventually stops producing a visible hair. That is why it happens slowly, at the temples, at the crown, or at both.
Source: patient information leaflet for Finasterid Medreg 1 mg (archived copy, revised 8. 8. 2018).
How it works
Finasteride and hair: how the medicine works
Finasteride is among the medicines you hear about most often. It helps many men. But it also has side effects that you have a right to know about beforehand, not from the small print afterwards. Here is the straight version from doctors who might prescribe it to you.
Finasteride blocks the enzyme that turns testosterone into DHT. With less DHT, the follicles are under less pressure, hair loss slows down, and in many men some hair grows back. For hair, a low dose is used, finasteride 1mg: one tablet a day, with or without food.
According to the EMA, finasteride 1 mg tablets and finasteride skin spray are intended in EU member states for men aged 18 to 41 with early androgenetic alopecia. The patient leaflet of the Czech product adds that the medicine is not for women and must not be taken by children or adolescents. (Finasteride 5 mg, which you may read about online, is a different medicine used for an enlarged prostate, not for hair.)
Sources: EMA, review of finasteride and dutasteride; information letter on finasteride and dutasteride of 12. 9. 2025; patient information leaflet for Finasterid Medreg 1 mg (archived copy, revised 8. 8. 2018).
What to expect
Finasteride experiences and results: what you can expect
It is a slow treatment, and patience comes with it. You take one tablet a day. Most men see no big change in the first three to six months, and whether the medicine is working can only be judged reliably after about a year.
It works best at keeping what you have. Many men stop losing hair, and some notice clear regrowth, especially at the crown. It is less likely that finasteride will restore a hairline that has receded a long way. The leaflet states that a benefit can be expected in men with mild to moderate hair loss, not in men with complete hair loss.
What people often do not know: the medicine only works while you take it. If you stop, you usually lose the hair you kept or regrew within roughly the following year. The leaflet speaks of 9 to 12 months.
Source: patient information leaflet for Finasterid Medreg 1 mg (archived copy, revised 8. 8. 2018).
Safety
Finasteride side effects, without sugar-coating
Most men who take finasteride have no problems with it. A minority do, and some side effects are serious enough that we want to tell you about them beforehand, not afterwards.
Mood and mental health
In 2025 the European Medicines Agency (EMA) completed a Europe-wide safety review of medicines containing finasteride and dutasteride. It confirmed suicidal thoughts as a side effect of finasteride tablets; a warning about mood changes including depression was already in the product information. How often this happens cannot be estimated from the available data (the EMA gives the frequency as “not known”), but most of the reports came from people taking 1 mg tablets for hair loss.
If you have ever had depression, anxiety or suicidal thoughts, please tell us before treatment starts. Finasteride does not automatically rule you out, but it is an important part of the conversation.
Sex life
A minority of men notice changes, for example:
- lower sex drive
- difficulty getting an erection
- changes in ejaculation, including a smaller amount of semen
The leaflet states that these problems were usually temporary with continued treatment or disappeared after it stopped. In some men, however, they continued after treatment ended (more below). The EMA review also found cases where sexual dysfunction itself contributed to the development of mood changes. So if anything changes, tell your doctor early; the doctor may consider ending the treatment. It is a perfectly ordinary topic, and you will not be the first.
Breast changes
In some men the breasts swell or become tender. The leaflet also warns that changes in breast tissue, such as lumps, pain, enlargement or discharge from the nipple, can be signs of a serious condition including breast cancer. If you notice them, have them checked promptly.
Fertility
Infertility has been reported in men who took finasteride for a long time and had other risk factors affecting fertility. After stopping, recovery or improvement of semen quality was reported. Long-term clinical studies of finasteride’s effect on fertility have not been carried out. If you are planning a child with your partner, it is better to discuss it with a doctor beforehand.
Less common effects
Some men reported allergic reactions (rash, itching, hives or swelling of the lips, tongue, throat and face), anxiety, testicular pain, palpitations or raised liver enzymes.
Sources: EMA, review of finasteride and dutasteride; EMA, changes to the product information (Annex III); information letter on finasteride and dutasteride of 12. 9. 2025; patient information leaflet for Finasterid Medreg 1 mg (archived copy, revised 8. 8. 2018).
After stopping
Problems that continue after stopping finasteride
Online, the name “post-finasteride syndrome” is used for problems that continue after finasteride is stopped. That name does not appear in the Czech and European texts we checked for this article, so we set out what they say.
The leaflet lists, among the side effects, persistent erectile difficulties, persistently reduced sex drive and persistent ejaculation problems after treatment ends. It lists anxiety separately. For all of these effects the frequency is “not known”, which means it cannot be estimated from the available data. After the EMA review, suicidal thoughts have the same frequency, “not known”.
So we cannot tell you how many men are affected. We know that such problems are reported. If you notice sexual or mood problems during treatment, or if they continue after it ends, it is best to contact a doctor early.
Sources: patient information leaflet for Finasterid Medreg 1 mg (archived copy, revised 8. 8. 2018); EMA, changes to the product information (Annex III).
In the pack
The patient card in the pack
After the EMA review, packs of medicines containing finasteride 1 mg are to include a small patient card. It summarises the risks of mood changes, including suicidal thoughts, and of sexual dysfunction, and advises what to do if they appear: with any change in mood, stop taking finasteride and speak to a doctor as soon as possible. It is worth reading it properly together with the leaflet and keeping it where you can find it.
Sources: EMA, changes to the product information (Annex III); information letter on finasteride and dutasteride of 12. 9. 2025.
Good to know
A few practical points
- PSA test: finasteride can affect the result of the PSA (prostate-specific antigen) blood test used to check the prostate. If you ever have one, tell the doctor that you take finasteride so that they can interpret the result correctly.
- Pregnant partner: women must not take finasteride. Pregnant women and women planning a pregnancy must not touch broken or crushed tablets, because the active substance can affect the development of the child’s sex organs. Intact tablets are coated, which prevents contact with the active substance during normal handling.
- Blood donation: if you donate blood, tell the transfusion department that you take or have taken finasteride. According to the blood donor information of the General University Hospital in Prague, people taking certain medicines for hair loss and an enlarged prostate, finasteride among them, are excluded from donating for the long term. The length of the exclusion depends on the medicine and how it is given, and the doctor of the transfusion service decides on it.
- Topical options: in its review the EMA found no evidence that suicidal thoughts are linked to finasteride in skin spray form, and the information letter for Czech doctors states that there is not enough evidence for a causal link between topical finasteride and suicidal thoughts. This applies only to suicidal thoughts, not to a guarantee that a topical product has no side effects. According to the letter, the finasteride skin spray is authorised for the same indication. Whether topical finasteride suits you is worth discussing with a doctor.
Sources: patient information leaflet for Finasterid Medreg 1 mg (archived copy, revised 8. 8. 2018); General University Hospital in Prague, Faculty Transfusion Department: blood donor information (valid from 1. 9. 2024); EMA, review of finasteride and dutasteride; information letter on finasteride and dutasteride of 12. 9. 2025.
Your decision
Is finasteride right for you?
Overall, the EMA concluded that the benefits of medicines containing finasteride continue to outweigh their risks for all approved uses. But that is a judgement about large groups of people. Whether it makes sense for you depends on your medical history, on how much hair loss bothers you, and on how you feel about possible side effects. There is no wrong answer.
It is not the only option either. Topical minoxidil, topical finasteride, light therapy and hair transplants have their place, and some men simply decide not to treat their hair loss. That is a perfectly valid choice too.
Online care
We will talk it through together
Our doctors will see you on a video consultation, look at your hair loss, go through your medical and mental health history, and help you weigh your options without any pressure.
If you decide on finasteride, we will keep asking how you are feeling, not only how your hair is doing. Some cases need an in-person examination, and the doctor will tell you whether yours is one of them.
Book a hair loss consultation and we will go through the benefits, side effects and alternatives with our doctor.
Help
If you are struggling right now
Reporting
Reporting side effects
If you suspect a side effect, tell your doctor or pharmacist. You can also report the suspicion yourself to the State Institute for Drug Control (SÚKL). The most convenient way is the electronic form, which guides you through all the required details; you will find the details at sukl.gov.cz/nezadouciucinky. You can also report by email to farmakovigilance@sukl.gov.cz or by phone on 272 185 322 or 272 185 885 (on working days from 8.30 to 15.30). You will find instructions for patients on the public administration portal; the most important are serious effects and reactions that the leaflet does not list. Every report helps make medicines safer for the next person.
Care in Czechia
Talk to a doctor about hair loss
A video consultation can cover your hair loss, your medical and mental health history and your treatment options, including the decision not to treat your hair loss.
- Online consultation: hair loss
- MUDr. Vojtěch Černý, MBA, LL.M.: doctor profile
- Our doctors
- More blog articles
Thinking about finasteride? Let us talk it through first.
Go through your hair loss, your history and the possible side effects with our doctor on a secure video call, with no pressure to start treatment.
Sources
Evidence behind this article
Sources checked on 24 October 2026.
The EMA published the review for both finasteride and dutasteride; this article concerns finasteride only. The Czech information letter of 12. 9. 2025 comes from the marketing authorisation holders in agreement with the EMA and SÚKL, and we refer to its copy on the website of the Society of General Medicine of the ČLS JEP. The information on use and side effects comes from the patient leaflet of one Czech finasteride 1 mg product in an archived copy from 2018 (older than the 2025 changes, which are added from the EMA texts); the leaflets of other products may differ. The age range of 18 to 41 is given by the EMA for EU member states, not for a specific Czech product. The article describes the risks and what a consultation can cover; the treatment decision is made by a doctor after an individual assessment.
Frequently asked questions
Frequently asked questions about finasteride side effects
Finasteride side effects: what should you watch for?
Most men have no problems. A minority notice mood changes, including low mood and suicidal thoughts, or sexual problems such as reduced sex drive, difficulty getting an erection and less semen. Breast tenderness or enlargement, allergic reactions and testicular pain have also been reported. If your mood changes, stop taking finasteride and speak to a doctor.
How long does finasteride take to work?
Most men see no big change in the first three to six months, and whether the medicine is working can only be judged reliably after about a year. It works best at keeping what you have; it is less likely to restore a hairline that has receded a long way.
Will my hair stay if I stop finasteride?
Usually not. The medicine only works while you take it. The leaflet states that after treatment ends you are likely to lose the hair you gained within 9 to 12 months.
Can problems continue after stopping finasteride?
Online, the name post-finasteride syndrome is used for this. That name does not appear in the Czech and European texts we checked, but the leaflet lists persistent sexual problems after treatment ends as a side effect with a frequency that cannot be estimated. If you notice such problems, contact a doctor early.
Is topical finasteride linked to suicidal thoughts?
In its 2025 review the EMA found no evidence of a link between suicidal thoughts and finasteride in skin spray form, and the information letter for Czech doctors states that there is not enough evidence for a causal link. This applies only to suicidal thoughts. Whether topical finasteride suits you is worth discussing with a doctor.
Finasteride experiences: can you rely on stories from the internet?
The experiences of individual men differ and do not tell you how common each problem is. For suicidal thoughts, for example, the EMA states that the frequency cannot be estimated from the available data. When you make your decision, a conversation with a doctor who knows your history will therefore help you more.
