Does finasteride have side effects? An honest guide before you start
Finasteride works well for many men and has side effects worth knowing from the start. This guide explains how it works, what results to expect, what the EMA safety review concluded in 2025 and how to report a problem.
Does finasteride have side effects? Yes: most men have no problems, but a minority do, and some effects are serious enough to know about before you start. The main ones are mood changes, including low mood and suicidal thoughts, and sexual problems such as reduced desire. If your mood changes, stop taking it and speak to a doctor. Our doctors can go through the risks, your history and your options with you by video call, with no pressure.
Causes
Why does hair thin? Genes and DHT
If you have noticed your hairline receding or the crown thinning, you are not alone. Male pattern hair loss is common and, for many men, begins in their twenties. It is not a medical emergency, but it can affect confidence, and wanting to do something about it is reasonable.
It mostly comes down to two things: your genes and a hormone called DHT (dihydrotestosterone). If you have inherited sensitive follicles, DHT gradually shrinks them. Each new hair grows back a little finer and shorter than the last, until the follicle stops producing visible hair. That is why it usually happens gradually, at the temples, the crown or both.
How it works
Finasteride: what it is used for and how it works
Finasteride is one of the treatments you will hear about most. For many men it works well. It also has side effects you deserve to know about from the start, not buried in the small print. This is the straightforward version, from the doctors who would prescribe it.
Finasteride blocks the enzyme that converts testosterone into DHT. Less DHT means less pressure on the follicles, so hair loss slows down and, in many men, some hair grows back.
In Spain, the 1 mg finasteride tablet is licensed for men aged 18 to 41 for the early stages of male pattern hair loss. (You may see a 5 mg version mentioned online. That is a different medicine, used for benign prostate enlargement, not for hair.) Finasteride tablets are not intended for women or for anyone under 18.
Sources: AEMPS (CIMA), finasteride 1 mg: summary of product characteristics; package leaflet.
What to expect
Finasteride before and after: what results to expect
It is a slow treatment, and patience is part of it. You take one tablet a day, with or without food. Most men do not notice much change during the first three to six months, and it is usually around the one-year mark that you can judge properly whether it is working.
Its strength is keeping the hair you have. Many men stop losing hair and some get a noticeable regrowth, especially at the crown. It is less likely to rebuild a hairline that has already receded a long way.
The “before and after” photos that circulate online show individual cases, and results vary from one man to another. According to the summary of product characteristics, the doctor should continually assess whether the treatment is working in each case.
Something many people do not know: it only works while you take it. If you stop, the hair you kept or regained is usually lost again over roughly the following year.
Sources: AEMPS (CIMA), finasteride 1 mg: summary of product characteristics; package leaflet.
Safety
Does finasteride have side effects? What you should know
Most men who take finasteride have no problems at all. But a minority do, and some of those effects are serious enough that we want you to know about them before you decide, not after.
Mood and mental health
In 2025, the European Medicines Agency (EMA) concluded a Europe-wide safety review of medicines containing finasteride and dutasteride. It confirmed suicidal ideation as an adverse effect of finasteride tablets; warnings about mood changes, including depression, were already in the product information. It is not possible to say exactly how often this happens (the frequency is classed as “not known”), but most of the reported cases involved men taking the 1 mg tablet for hair loss. The AEMPS reported this risk in a safety note in May 2025, and in September 2025 a communication on it was sent to healthcare professionals, in agreement with the EMA and the AEMPS.
If you have ever had depression, anxiety or suicidal thoughts, tell us before you start. It does not automatically rule finasteride out, but it is an important part of the conversation.
Sex life
A small number of men notice changes such as:
- lower sex drive
- difficulty getting or keeping an erection
- changes in ejaculation, including a smaller amount of semen
In most men they go away when the tablets are stopped. In some, however, they have continued after treatment ended (more on this below). The EMA review also found cases in which these sexual effects contributed to changes in mood. So if anything changes, tell your doctor early. It is a completely normal thing to raise, and you will not be the first.
Breast changes
Some men notice breast tenderness or enlargement. Breast cancer has also been reported in men taking finasteride. If you notice a lump, pain, swelling or any discharge from the nipple, get it checked without delay.
Fertility
Poor semen quality and infertility have been reported in men taking finasteride, in some cases alongside other risk factors. Improvement after stopping has also been reported. If you and your partner are trying for a pregnancy, it is worth discussing this beforehand.
Less common effects
Some men have reported allergic reactions (rash, itching, hives or swelling of the lips, tongue or face), testicular pain, blood in the semen, palpitations or changes in liver tests. If you ever have difficulty breathing or swallowing, treat it as an emergency and get help immediately.
Sources: European Medicines Agency, review of finasteride and dutasteride; AEMPS, safety note of May 2025; AEMPS, communication to healthcare professionals (12 September 2025); CIMA, summary of product characteristics; package leaflet.
After stopping
Post-finasteride syndrome: symptoms that continue after stopping
“Post-finasteride syndrome” is a name you will see online for symptoms that continue after stopping finasteride. The Spanish-authorised product information we reviewed does not use that name, and this is what it does say.
The package leaflet lists, among the reported adverse effects, persistent difficulty getting an erection, persistently reduced sex drive and persistent ejaculation problems after treatment is stopped. Separately, it includes anxiety and suicidal thoughts. For all of these the frequency is “not known”, meaning it cannot be estimated from the available data.
That is why we cannot tell you how many men are affected. What we can say is that it has been reported, and that if you notice sexual or mood symptoms during treatment, or if they continue after you stop, it is best to tell a doctor early.
Sources: AEMPS (CIMA), finasteride 1 mg: package leaflet; summary of product characteristics.
In the pack
The card that comes in the box
Following the EMA review, packs of finasteride 1 mg include a small patient information card. It summarises the risks of mood changes, including suicidal thoughts, and of sexual problems, and what to do if they appear. Read it carefully, together with the leaflet, and keep it somewhere you can find it.
Sources: European Medicines Agency; AEMPS, safety note of May 2025; AEMPS (CIMA), package leaflet.
Good to know
A few practical points
- PSA test: finasteride lowers the PSA (prostate-specific antigen) level, a blood test used to monitor the prostate. If you ever have one, tell the doctor you take finasteride so they can interpret the result correctly.
- If your partner is pregnant: finasteride can affect the development of a male foetus. Women who are or may be pregnant should not handle crushed or broken tablets. Whole tablets are coated and can be handled normally.
- Donating blood: the Spanish regulation on blood donation states that, for medication, exclusion depends on the nature of the medicine, how it works and the condition it is taken for. If you donate blood, tell the donation team you take finasteride and follow their instructions.
- Topical options: the EMA review found no evidence linking finasteride skin spray with suicidal ideation, so its product information did not change. That finding concerns suicidal ideation only; it does not guarantee that a topical product has no side effects. A finasteride solution for spraying on the skin is authorised in Spain with the same indication, and topical finasteride may be worth a conversation with your doctor, depending on your case.
Sources: AEMPS (CIMA), finasteride 1 mg: package leaflet; summary of product characteristics; Real Decreto 1088/2005, annex II; European Medicines Agency; AEMPS, communication of September 2025.
Your decision
So is finasteride right for you?
Overall, the EMA concluded that the benefits of finasteride continue to outweigh its risks. But that is a judgement about large groups of people. Whether it makes sense for you depends on your health history, how much the hair loss bothers you and how you feel about the possible side effects. There is no wrong answer.
It is not the only option either. Topical minoxidil, topical finasteride, light therapy and hair transplants all have their place, and some men simply decide not to treat. That is an equally valid decision.
Minoxidil and finasteride are different medicines. Minoxidil is applied to the scalp, and its Spanish summary of product characteristics says its mechanism of action is not fully understood. Finasteride tablets work by reducing DHT. Minoxidil also has its own precautions: it should not be applied at the same time as other skin products, such as corticosteroids or retinoids, and if you have a history of heart or blood vessel disease, your doctor should monitor your blood pressure and heart rate. Whether one, the other or both suit you is something a doctor can assess after going through your history.
Sources: European Medicines Agency; AEMPS (CIMA), minoxidil 50 mg/ml cutaneous solution: summary of product characteristics; package leaflet.
Online care
Talk to us
Our doctors can see you by video call, assess your hair loss, go through your medical and mental health history and help you weigh up the options without any pressure.
If you decide to use finasteride, we will keep asking how you are, not just how your hair is doing. Some cases need an in-person examination, and your doctor will tell you if yours is one of them.
Book a hair loss consultation to talk about the benefits, side effects and alternatives with one of our doctors.
Support
If you are struggling right now
Reporting
How to report a side effect
If you think you have a side effect, talk to your doctor or pharmacist. When someone suspects a medicine has caused an adverse reaction, they can also report it directly through the notificaRAM online form of the Spanish Pharmacovigilance System. The AEMPS page on reporting gives more information. Reporting does not replace seeing a doctor, so tell them about your symptoms as well. Every report helps make medicines safer for the next person.
Next step
Talk to a doctor about hair loss
A video consultation can go through your hair loss, your medical and mental health history and your options, including the option of not treating it.
Thinking about finasteride? Talk to a doctor first.
Go through your hair loss, your history and the possible side effects with one of our doctors on a secure video call, with no pressure to start a treatment.
Sources
The evidence this article is based on
Sources consulted on 24 October 2026.
The EMA review and the AEMPS communications cover finasteride and dutasteride; this article deals with finasteride only. The September 2025 communication is a letter addressed to healthcare professionals by the marketing authorisation holders, in agreement with the EMA and the AEMPS. The product data come from a finasteride 1 mg authorised in Spain and a cutaneous minoxidil; other brands may differ. This article describes the risks and what a consultation can cover; any treatment decision is made by a doctor after an individual assessment.
Frequently asked questions
Frequently asked questions about finasteride
Does finasteride have serious side effects?
Most men have no problems. A minority notice mood changes, including low mood and, with an unknown frequency, suicidal thoughts, or sexual effects such as lower desire, difficulty with erections and less semen. Breast changes and allergic reactions have also been reported. If your mood changes, stop taking finasteride and speak to a doctor.
Finasteride: what is it used for and who can use it?
The 1 mg finasteride tablet is licensed in Spain for men aged 18 to 41 with early-stage male pattern hair loss. It works by reducing DHT, the hormone that shrinks follicles. It is not intended for women or for anyone under 18, and the 5 mg version is a different medicine, for the prostate.
How long does finasteride take to show results?
Most men do not notice much change during the first three to six months, and it is usually around the one-year mark that you can judge properly whether it works. It only works while you take it: if you stop, the hair you kept or regained is usually lost again over roughly the following year.
What is post-finasteride syndrome?
It is a name used online for symptoms that continue after stopping finasteride. The Spanish-authorised product information we reviewed does not use that name, but it does list sexual problems that persist after treatment is stopped as reported effects, with a frequency that cannot be estimated. If you notice symptoms like these, tell a doctor early.
Is topical finasteride linked to suicidal thoughts?
The EMA review of 2025 found no evidence linking finasteride skin spray with suicidal ideation, and the AEMPS states that its product information is therefore not being changed. That finding concerns suicidal ideation only. Whether topical finasteride suits you is something to discuss with a doctor.
Can minoxidil and finasteride be used together?
That is a decision for a doctor who knows your history. They are different medicines that work in different ways, and minoxidil has its own precautions: it should not be applied at the same time as other skin products, such as corticosteroids or retinoids, and with heart or blood vessel disease, blood pressure and heart rate should be monitored.
