How does the hair-loss drug finasteride work? Can it affect my mental health?

For many men the gradual thinning of hair is about more than just their appearance. Finasteride, a drug widely prescribed for the treatment of male pattern baldness has been used effectively for many years for this deeply personal problem.

Yet, behind its use are growing concerns about its link to the development of depression, anxiety, and even suicidal thoughts.

There is now critical discussion among both users and health-care professionals about the potential hazards associated with its continued use.

So how does the drug work? And what does the evidence say about the risk of developing a mental health problem?

How does finasteride work?

Finasteride is used to treat androgenetic alopecia, also known as male pattern baldness. It works to regrow hair and prevent the further loss of hair.

One of the key causes of pattern baldness is the production of a hormone called dihydrotestosterone which the body makes from testosterone. When it binds to the follicles of hairs, it initiates a process called hair follicle miniaturisation. This is where the growth cycle of the hair becomes progressively shorter, resulting in thinner and weaker hair.

Finasteride works by blocking the enzyme that converts testosterone to dihydrotestosterone. By blocking the enzyme, dihydrotestosterone concentrations can be reduced by around 60–70% for the majority of men.

Finasteride was first approved in the late 1990s as a prescription-only medicine and is taken as a daily 1 milligram oral tablet. Medications available at a higher 5 mg daily dose are not used for baldness, but as a treatment for non-cancerous prostate enlargement.

This medication is not indicated for women, even though they can also have this type of hair loss.

How can it impact your mental health?

Changes in mental health are not listed as an established side effect in Australian guidance given to health-care professionals.

Based on clinical trials, the most common effects include:

• decreased libido
• erectile dysfunction
• reduced semen production.

The guidance also describes an increased risk of prostate cancer and a potential risk for breast cancer. Yes, men can get breast cancer too.

While initial clinical trials conducted to obtain approval for the drug didn’t demonstrate mental health concerns, monitoring of patients using the drug has since indicated a potential increased risk of depression and suicidal thoughts. But as this is based on patients self-reporting symptoms, according to the guidance there is no definitive link.

However, in May 2025, the European Medicines Agency safety committee stated suicidal thoughts was a confirmed side effect of finasteride. The European Union also advises patients that finasteride can cause a depressed mood and depression.

Similarly, in a warning about compounded finasteride, the United States Food and Drug Administration stated in April 2025 that topical formulations of the drug has similar side effects to the oral version. These include depression, anxiety and suicidal thoughts.

What should you do if it is affecting your mental health?

If you notice changes in your mental health while taking the drug, try not to handle significant mood changes by yourself. If you’re feeling unusually low, anxious or emotionally unstable, check in with a doctor so they can help you figure out whether finasteride is contributing to your mood and what support you may need.

If the symptoms are mild, they may suggest pausing finasteride to see whether things improve, or continuing with additional mental health support. If your symptoms are more severe, stopping the medication and getting prompt medical review may be appropriate.

If you are taking finasteride and are worried about its side effects, it is safe to stop immediately. Most side effects ease once the medication is out of your system, although a small number of people have reported symptoms that persist.

If you do decide to stop, this will mean that your hormone levels will gradually return to baseline and the hair growth seen with the drug will be lost over time.

If finasteride is not the right fit for you, there is another evidence-based alternative.

Topical minoxidil is a first-line treatment that can be used on its own or with other treatments and is available from pharmacies over the counter. It only works while it’s being used and may irritate the scalp, but its effectiveness is well-established and widely recommended.

While depression and anxiety are associated with minoxidil, the incidence is much lower because of their topical application.

There is also a medication called dutasteride. However, as it works in a similar way to finasteride, it may also increase your risk of developing mental health problems. So it is best to avoid dutasteride if finasteride is not suitable for you.

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