Finasteride
Also known as: Proscar, Propecia
Finasteride is a tablet that stops testosterone turning into the hormone DHT, used for an enlarged prostate and for male pattern hair loss. The NHS and the MHRA both describe warnings about low mood, depression and suicidal thoughts, and about sexual side effects that can carry on after the medicine is stopped. For hair loss it is available on a private prescription only, not on the NHS.
- Generic name
- Finasteride
- Active ingredient
- Finasteride
- Product type
- Small-molecule medicine
- Drug class
- 5-alpha reductase inhibitors
- Brand names
- UK Proscar, Propecia
- Routes
- Oral
- Dosage forms
- Tablet
- Also known as
- Proscar, Propecia
- Usual preparations
- Taken by mouth as a tablet. (summary of the cited reference, not a prescription)
- Onset and duration
- The NHS says it can take several months to work fully for an enlarged prostate, and some improvement in hair loss may be seen after a few months.
- Monitoring
- The MHRA advises prescribers to ask about depression and suicidal thoughts and to review men on finasteride regularly. Suspected side effects can be reported to the MHRA through the Yellow Card scheme.
Availability by country
| Country | Status | Note | Source |
|---|---|---|---|
| UK | Prescription only | UK |
Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.
What it is used for
- Benign prostate enlargement (an enlarged prostate), for which the NHS says it is available on NHS prescription
- Male pattern hair loss, for which the NHS says it can only be obtained on a private prescription
How it works in the body
Finasteride is a 5-alpha reductase inhibitor. It works by stopping testosterone, a sex hormone, from turning into another hormone called dihydrotestosterone (DHT).
Common side effects
- The NHS names losing interest in sex and difficulty getting an erection as the most common side effects.
- Ejaculation problems are also on the NHS list of common side effects.
- These effects usually improve after a while but can sometimes carry on after finasteride is stopped.
Serious: seek help
- The NHS lists low mood (depression) as a rare serious side effect, advises contacting a doctor or NHS 111 straight away, and for hair loss advises stopping the medicine straight away if low mood develops. The NHS says to call 999 or go to A&E if there are thoughts of harming oneself. In a mental-health crisis the routes to help are 999 if in immediate danger, NHS 111 (mental health option) and Samaritans on 116 123, which is free at any time.
- The MHRA says finasteride is associated with depression, suicidal thoughts and sexual dysfunction, and that the sexual problems may persist after treatment is stopped.
- The NHS advises speaking to a doctor about any lumps, pain or swelling in the chest area or discharge from the nipples, and notes that breast cancer has been reported rarely in men taking finasteride.
- The NHS lists anaphylaxis, a serious allergic reaction, as a rare side effect that may need immediate treatment in hospital; swelling of the face, tongue or throat with difficulty breathing is an emergency, so call 999.
Cautions and interactions
- The NHS says most men aged 18 or over can take finasteride, and that it is generally not recommended for women or children.
- The NHS asks that a doctor knows about a past allergic reaction to finasteride, a history of depression or thoughts of self-harm, severe bladder problems or liver problems.
- Finasteride can affect PSA (prostate-specific antigen) blood test results used to check for prostate cancer, so the NHS says a man needing a PSA test should tell the doctor he takes it.
- Hospital information for women says finasteride must not be used in pregnancy or when breastfeeding, and that people taking it must not donate blood.
- MedlinePlus (a US source) says touching broken or crushed tablets may harm an unborn baby, and that a woman who is or could be pregnant and touches them should wash the area with soap and water straight away and call a doctor.
- The NHS notes that some men taking finasteride have reported test results showing poor sperm quality or infertility, but that this is not a common side effect and sperm quality usually returns to normal after stopping.
- The NHS says alcohol can be drunk while taking finasteride.
- The MHRA advises prescribers to ask about any history of depression or suicidal thoughts and to review men on finasteride regularly.
Interactions
Check interactions
Taking Finasteride with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".
Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.
No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.
Same-class and related medicines
Same class: 5-alpha reductase inhibitors
Medicines that share the class of Finasteride. They are separate medicines with their own licences, doses and interactions, not alternative names for Finasteride.
Key facts
| Fact | Detail |
|---|---|
| Brand names (UK) | Proscar, Propecia |
| Drug class | 5-alpha reductase inhibitor |
| Used for | Enlarged prostate; male pattern hair loss |
| Availability | Hair loss: private prescription only. Enlarged prostate: NHS prescription |
| Main side effects | Losing interest in sex; difficulty getting an erection |
| Mood warning | Low mood, depression and suicidal thoughts have been reported |
| Blood test effect | Can affect PSA test results |
What is finasteride used for and how does it work?
Finasteride is a tablet taken by mouth. The NHS describes two uses: treating an enlarged prostate, which doctors call benign prostate enlargement, and treating male pattern baldness. For an enlarged prostate it is available on an NHS prescription, while for hair loss the NHS says it can only be obtained on a private prescription, so the person pays the full cost. Finasteride is a 5-alpha reductase inhibitor, which means it stops testosterone, a sex hormone, turning into another hormone called DHT. The NHS says it can take several months to work fully for an enlarged prostate, and some improvement in hair loss may be seen after a few months. The NHS says most men aged 18 or over can take it and that it is generally not recommended for women or children. Brand names include Proscar and Propecia. The MHRA has also added a precautionary warning to the product information for dutasteride, a similar medicine, that mood changes have been reported with finasteride, which is in the same class.
What are the sexual side effects of finasteride?
The NHS names losing interest in sex and difficulty getting an erection as the main side effects of finasteride. Ejaculation problems are also on its list of common side effects. They usually improve after a while but can sometimes carry on even after finasteride is stopped. Some men have reported that sexual side effects kept bothering them after they stopped taking it. The MHRA drug safety updates make the same point, noting reports of sexual dysfunction that continued after treatment ended. In 2026 the MHRA said the product information for the hair-loss tablet is being updated to state that sexual dysfunction may contribute to mood disorders, and that it has also been reported without any change in mood. Men with concerns about sexual side effects are asked to discuss them with a healthcare professional. The NHS notes that some men taking finasteride have reported test results showing poor sperm quality or infertility, but says this is not a common side effect and that sperm quality usually returns to normal after stopping.
Mood changes, depression and suicidal thoughts
The NHS lists low mood, or depression, as a rare side effect of finasteride. The NHS advises contacting a doctor or NHS 111 straight away for low mood, and for men taking it for hair loss, stopping the medicine straight away. The MHRA says finasteride is associated with depression, suicidal thoughts and sexual dysfunction. Its 2026 update says men who develop depression or suicidal thoughts on the hair-loss tablet should stop it and contact their doctor. The MHRA also advises prescribers to ask about any past depression or suicidal thoughts and to review men regularly. Earlier, it introduced a patient alert card to raise awareness of the possible psychiatric and sexual side effects. The NHS asks that a doctor knows beforehand about a history of depression or thoughts of self-harm. For thoughts of harming oneself, the NHS says to call 999 or go to A&E. In a mental-health crisis the routes to help are 999 if in immediate danger, NHS 111 (mental health option) and Samaritans on 116 123, which is free at any time. Suspected side effects can be reported through the Yellow Card scheme.
PSA tests, breast changes and pregnancy
Finasteride can affect the results of a PSA test, a blood test used to check for prostate cancer. The NHS says a man who needs a PSA test should tell the doctor he is taking finasteride. On breast changes, the NHS says to speak to a doctor about any lumps, pain or swelling in the chest area, or discharge from the nipples. The NHS also notes rare reports of breast cancer in men taking finasteride. Hospital information for women says finasteride must not be used during pregnancy or breastfeeding, and that people taking it must not donate blood. MedlinePlus, a US source, says touching broken or crushed tablets may harm an unborn baby. It adds that a woman who is or could be pregnant and touches them should wash the area with soap and water straight away and call a doctor. The NHS says alcohol can be drunk while taking finasteride.
Frequently asked questions
Can finasteride cause depression?
The NHS lists low mood, or depression, as a rare side effect, and the MHRA says finasteride is associated with depression and suicidal thoughts. The NHS advises contacting a doctor or NHS 111 straight away for low mood, stopping straight away if taking it for hair loss, and calling 999 or going to A&E for thoughts of self-harm.
Do the sexual side effects go away after stopping finasteride?
The NHS says side effects usually improve after a while but can sometimes carry on after stopping. The MHRA notes reports of sexual dysfunction that continued after treatment ended, and men with concerns are asked to discuss them with a healthcare professional.
Can women handle finasteride tablets?
MedlinePlus, a US source, says touching broken or crushed tablets may harm an unborn baby. A woman who is or could be pregnant and touches them is advised to wash the area with soap and water straight away and call a doctor.
Does finasteride affect a PSA test?
The NHS says finasteride can affect PSA results, a blood test used to check for prostate cancer. A man who needs the test is asked to tell the doctor he takes it.
Is finasteride for hair loss available on the NHS?
The NHS says finasteride for hair loss can only be obtained on a private prescription, with the person paying the full cost. It is available on NHS prescription for an enlarged prostate.
Connected pages in detail
What each linked page on Anatomy Nexus covers, in a line, for Finasteride.
Symptoms
- Breast lump A new lump, or an area of thickening that feels different from the rest of the breast, anywhere in the breast tissue.
Drug classes
- 5-alpha reductase inhibitors A group of medicines that stop testosterone turning into the hormone DHT; finasteride.