Finasteride side effects: an honest guide before you start
Finasteride works well for many men and has side effects you should know about from the start. This guide explains how it works, realistic results, the 2025 Anvisa alert and how to report a problem.
If you are searching for finasteride side effects, you want to know the risk before you decide: most men have no problems, but a minority have mood changes, including suicidal thoughts, or sexual problems such as reduced libido. If your mood changes, stop taking it and talk to a doctor. In an online consultation, our doctors explain the risks, review your history and go through the options with you, without pressure.
Causes
Why does hair thin?
If you have noticed your hairline receding or the crown of your head thinning, know that this is common. Male pattern baldness is frequent and, for many men, begins in their early 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.
It comes down to two factors: genetics and a hormone called DHT (dihydrotestosterone). If you inherit sensitive follicles, DHT gradually shrinks them. Each new hair grows a little finer and shorter than the last, until the follicle stops producing a visible hair. That is why the loss is usually gradual, at the temples, the crown or both.
How it works
What finasteride is for and how it works
Finasteride is one of the most frequently cited treatments. It works well for many men and has side effects that you deserve to know about right from the start, not buried in small print. This is the straightforward version, from someone who prescribes it.
Finasteride blocks the enzyme that converts testosterone into DHT. With less DHT, the follicles are under less pressure, the loss slows down and, in many men, some hair grows back.
In Brazil, the 1mg finasteride tablet is indicated for men with male pattern baldness (androgenetic alopecia) and is not indicated for women or children. The leaflets we consulted do not set an age range for this use. The 5mg version, which you may see mentioned online, is a different medicine, used for an enlarged prostate, and is not for hair.
Sources: Anvisa, Alert GGMON No. 07/2025; reference leaflet for finasteride 1mg (2023).
What to expect
Finasteride before and after: what to expect from the results
Finasteride for hair loss is a slow treatment, and patience is part of it. You take one tablet a day, with or without food. The leaflet says you need 3 months or more of daily use before you notice more hair growth. Most men do not see much change in the first three to six months, and it is around one year that you can really judge whether it is working.
So anyone searching for finasteride before and after photos needs to keep in mind that the result is gradual. It is best at keeping what you have. Many men stop losing hair and some see visible regrowth, mainly at the crown. It is less likely to rebuild a hairline that has already receded a long way.
One thing 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 about a year. The leaflet says the same: the effect of the medicine reverses within 12 months.
Safety
The side effects of finasteride, plainly
Most men who take finasteride have no problems with it. But a minority do, and some of those effects are serious enough that we want you to know about them before you decide, not afterwards.
Mood and mental health
In June 2025, Anvisa published Alert GGMON No. 07/2025, based on the safety review of finasteride and dutasteride by the PRAC committee of the European Medicines Agency (EMA). Anvisa states that there is evidence of a risk of sexual dysfunction, mood changes, depression and suicidal thoughts (suicidal ideation), especially with finasteride 1mg used for male hair loss. According to the alert, the frequency is unknown and cannot be estimated. Most cases of suicidal ideation were reported by people who used 1mg for hair loss, and these effects appeared even in people with no history of psychiatric disorder. The finasteride leaflet already carried a warning about mood changes, including depression and suicidal ideation.
If you have had depression, anxiety or suicidal thoughts, tell the doctor before you start. This does not automatically rule out finasteride, but it is an important part of the conversation. Anvisa recommends that all patients are assessed for suicidal ideation, self-harm, depression and risk factors before starting treatment.
Sex life
A small number of men notice changes such as:
- reduced libido (sexual desire)
- difficulty getting or keeping an erection
- changes in ejaculation, including a smaller volume of semen
For most men, this goes away when treatment is stopped. In some, however, the problems continued after treatment ended. The European review also notes that sexual problems can contribute to mood changes. So if anything changes, talk to a doctor early on: it is a normal subject to raise, and you will not be the first. Anvisa's guidance to patients is to stop treatment and seek medical care as soon as possible if mood changes, persistent sadness, thoughts of self-harm or sexual dysfunction appear.
Breasts
Some men have breast tenderness or enlargement. There have also been reports of breast cancer in men who were using finasteride. If you notice a lump, pain, swelling or nipple discharge, seek medical assessment promptly.
Fertility
Male infertility and poor semen quality have been reported in men who used finasteride, as well as improvement after stopping treatment. If you and your partner are trying for a baby, it is worth discussing this before you start.
Less common effects
Some men have reported allergic reactions (skin rash, itching, hives or swelling of the lips, tongue, throat or face), testicular pain and blood in the semen. If you have difficulty breathing or swallowing, treat it as an emergency and get help immediately.
Sources: Anvisa, Alert GGMON No. 07/2025; EMA, review of finasteride and dutasteride; reference leaflet for finasteride 1mg (2023).
After stopping
Post-finasteride syndrome: when symptoms continue after stopping
“Post-finasteride syndrome” is the name you will find online for symptoms that continue after a man stops taking finasteride. The Brazilian documents we consulted do not use that name, so here is what they say.
The Anvisa alert says that signs of depression, anxiety or suicidal thoughts should be monitored during and after treatment, because symptoms can persist after the medicine is stopped. The leaflet of the reference medicine lists, among the reported adverse reactions, sexual dysfunction (erectile dysfunction and ejaculation disorders) that continues after treatment is stopped. Anvisa states that the frequency of these adverse events is unknown.
In other words, we cannot say 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 that continue after you stop, the best thing is to tell a doctor early.
Sources: Anvisa, Alert GGMON No. 07/2025; reference leaflet for finasteride 1mg (2023).
Before you start
Read the leaflet before you start
Anvisa asked the registration holders of finasteride medicines to update the leaflet text with the risk and the precautions to take. For you, the guidance in the alert is simple: read the leaflet carefully, follow the instructions of the doctor and pharmacist, and use finasteride only with a prescription and medical follow-up. Uses outside the indications in the leaflet have no proven efficacy and can cause adverse events.
Source: Anvisa, Alert GGMON No. 07/2025.
Good to know
A few practical things worth knowing
- PSA test: finasteride lowers the PSA result, a blood test used to assess the prostate. If you are having the test, tell the doctor that you take finasteride, so that they interpret the result correctly.
- If your partner is pregnant: finasteride can affect the development of a male baby. Pregnant women, or women who could become pregnant, should not handle crushed or broken tablets. Whole tablets, with the coating intact, can be touched normally.
- Donating blood: men who take finasteride cannot donate blood, and the ineligibility continues after treatment ends: the Unicamp Blood Centre lists finasteride with 1 month of ineligibility after the medicine is stopped. If you donate blood, tell the blood centre team and follow their guidance.
- Topical finasteride: the European review, cited in the Anvisa alert, found no evidence linking suicidal ideation to finasteride skin sprays, and no new information was added to the leaflet of these sprays. This applies to suicidal ideation and does not guarantee that a topical product has no side effects. If a topical option makes sense in your case, talk to a doctor.
Sources: reference leaflet for finasteride 1mg (2023); Unicamp Blood Centre; Anvisa, Alert GGMON No. 07/2025; EMA.
Your decision
Minoxidil and finasteride: does finasteride make sense for you?
Overall, Anvisa states that the benefits of finasteride medicines continue to outweigh the risks for all approved uses, as concluded by the European review on which the alert is based. 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 transplantation all have their place, and some men simply prefer not to treat their hair loss. That is also a valid choice.
Minoxidil and finasteride are different medicines. Minoxidil is applied to the scalp, and the leaflet of a 5% minoxidil that we consulted indicates it for adult men with hereditary baldness. Finasteride in tablet form works by reducing DHT. Minoxidil also has its own precautions: that leaflet asks you to tell the doctor if you have heart disease and says not to use it together with other medicines applied to the scalp. Whether one, the other or both make sense for you is something a doctor can assess once they know your history.
Sources: Anvisa, Alert GGMON No. 07/2025; EMA; 5% minoxidil leaflet (Aché).
Online care
Talk to one of our doctors
Our doctors see you by video, assess your hair loss, review your medical and mental health history and help you weigh the options, without pressure.
If you decide on finasteride, we will keep following you up, including how you are feeling, and not only how your hair is doing. Some cases need an in-person examination, and the doctor will tell you if yours is one of them.
Book a hair loss consultation to talk about the benefits, the side effects and the alternatives.
Support
If you are struggling right now
Reporting
How to report side effects
If you suspect a side effect, talk to your doctor or pharmacist. You can also report it yourself to Anvisa through the VigiMed system: any citizen can use the form for citizens and professionals, without having to be a healthcare professional. For the report to be valid, you need to identify the patient and the person reporting, describe the adverse event and state the suspected medicine. Anvisa stresses the importance of reporting any suspected adverse event. Every report helps make medicines safer for the next person.
Care in Brazil
Talk to a doctor about hair loss
A video consultation assesses your hair loss, your medical and mental health history and your options, including the option of not treating.
Thinking about finasteride? Talk first.
Talk through your hair loss, your history and the possible side effects with one of our doctors, by secure video, with no pressure to start a treatment.
References
Sources consulted
Sources verified on 24 October 2026.
The Anvisa alert was read in the full text reproduced by Legismap, because the original alert page on the Anvisa website was not accessible on the day of verification. The EMA review is European: Anvisa cites it as the basis of the alert, and the patient card included in European packs does not appear in the Brazilian alert. The reference finasteride leaflet is a 2023 version, which predates the alert, and the leaflet that comes with your medicine is the valid version. The minoxidil data come from the leaflet of a 5% product, and others 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.
Questions
Frequently asked questions about finasteride
Finasteride side effects: what are the main ones?
Most men have no problems. A minority notice mood changes, including sadness and, less often, suicidal thoughts, or sexual effects such as reduced libido, difficulty with erections and a smaller volume of semen. There are also reports of breast changes, allergic reactions and testicular pain. If your mood changes, stop taking finasteride and talk to a doctor.
What is finasteride for?
Finasteride 1mg is indicated for men with male pattern baldness (androgenetic alopecia). It blocks the enzyme that converts testosterone into DHT, the hormone that shrinks follicles, and so slows the loss. It is not indicated for women or children, and the 5mg version is a different medicine, used for an enlarged prostate.
How long does finasteride take to show results, and what happens if I stop?
The leaflet speaks of 3 months or more of daily use before more growth is noticed. Most men do not see much change in the first three to six months, and it is around one year that you can judge whether it is working. It only works while you take it: when you stop, the hair you kept or regained is usually lost again over about 12 months.
Can finasteride side effects continue after I stop?
This has been reported. The Anvisa alert says mood symptoms can persist after the medicine is stopped, and the reference leaflet lists sexual dysfunction that continues after treatment ends. The Brazilian documents we consulted do not use the name “post-finasteride syndrome”, and the frequency is unknown. If you notice symptoms like these, tell a doctor early.
Does topical finasteride also carry a risk of suicidal thoughts?
The European review, cited by Anvisa, found no evidence linking suicidal ideation to finasteride skin sprays, and Anvisa did not ask for new information in the leaflet of these sprays. This concerns suicidal ideation only. If a topical option suits your case, it is worth talking to a doctor.
Can I use minoxidil and finasteride 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: the leaflet we consulted asks you to tell the doctor if you have heart disease and says not to use it together with other medicines applied to the scalp.
