Does Finasteride Affect Your Sperm? What the Evidence Shows

Key Takeaways

• What is Finasteride? Finasteride is an effective medication to slow the progression of male pattern hair loss at a 1mg dose.¹
  
• Are there any side effects? The main side effects you may be concerned about are losing interest in sex, the ability to get an erection, or noticing effects on your semen production. The best evidence reports these side effects as temporary while taking the medication. They do not usually continue after stopping use.
  
• What are its other uses? It is also used to treat an enlarged prostate gland (Benign prostatic hyperplasia or BPH), at a higher dose of 5mg.

You may be considering or have already started using finasteride to manage your hair loss. Perhaps you have heard it has certain side effects, especially in relation to semen production and function.

Below, we will discuss finasteride, its side effects, and what you should do if you have any concerns.

What Is Finasteride?

Finasteride is the gold standard medication for male pattern hair loss.

It is a prescription drug that reduces a form of testosterone called Dihydrotestosterone(DHT) in the body. 

This potent form of testosterone (DHT) is responsible for the thinning and shortening of susceptible hair follicles (miniaturisation). Ultimately,  the follicles stop making any new hair. It is the main culprit of pattern hair loss in men.²

It usually comes in two different dosages, i.e., 1 mg and 5mg. The 1mg dose is the one used most often for hair loss in men.

How Could Finasteride Affect Semen?

Finasteride works by reducing a derivative of testosterone in the body called DHT, which is the main cause of male pattern hair loss. 

While it works on hair follicles, it also works on other areas of the body. Its effect on semen is because DHT also acts in reproductive tissues like the prostate.³. The prostate happens to be one of the main producers of the liquid that semen is made of.

“Taking finasteride can affect family planning for some patients and at our clinic we are able to advise patients on alternative medications they can explore to help prevent hair loss as they look to have children”

Dr Roshan Vara, Hair Transplant Surgeon, The Treatment Rooms London

There are different characteristics of semen. The main ones are summarised in the table below.

Measure	What it means
Semen volume	The total amount of fluid expelled in a single ejaculation
Sperm count	The number of sperm present in the ejaculate (usually 2–5% of the total semen amount)
Motility	The ability of the sperm to propel themselves and move
Morphology	The shape of the sperm

Semen Volume

A study found semen volume to be modestly lower in healthy men who were treated with finasteride.⁴ This is currently explained by a decrease in stimulation of the prostate by DHT. This makes it smaller, and a smaller prostate produces less prostatic fluid to enter the ejaculate.

Total Sperm Count

In those taking finasteride (5mg a day), the number of sperm and sperm concentration were found to be modestly altered.^4,5 This effect was found to reverse after discontinuation, where sperm counts increased back to the typical baseline.⁶

Sperm Motility

The movement (motility) also appears to be affected, which would make it more difficult for sperm to reach the ovum. This can impact fertility if someone taking finasteride wishes to conceive.⁴

Sperm Morphology

The shape of sperm (Morphology) generally remains normal in most evidence we have. One study showed a potential link to higher abnormal forms of sperm in men taking finasteride 1mg/day. This effect lasted until discontinuation, whereby at a check-up a year later the sperm shape was found to be normal.^4,5

What Research Shows

There needs to be a distinction made here between the dosages commonly used to treat different conditions. In prostate enlargement (BPH), the dose is 5mg a day, and in male pattern hair loss, the dose is 1mg a day.

The adverse effects on semen were mainly found to be significant in the group using 5mg. The effects are not found to be as pronounced in those taking 1mg doses in hair loss treatment.⁷

Finasteride in Men With Existing Fertility Problems

If you suffer from existing fertility problems and are trying to conceive, it is not recommended to start on finasteride as the medication can adversely affect your sperm count and motility.

If you are already on Finasteride, stopping may see an increase in sperm count, so it is worth considering, depending on your goals.⁶ You should discuss your options further with your finasteride prescriber, your GP or your fertility specialist.

What Remains Uncertain?

Currently, we have little evidence on the long-term fertility impacts of finasteride. All the current data point to the fact that any effects are short-lived and will stop after you stop taking finasteride. 

There is also limited evidence on whether sperm DNA quality is impacted at all. We also need to discover the percentage of 1mg users who develop a clinically important sperm-count reduction. Another unknown aspect is whether taking finasteride for a longer period increases the risk of these effects.

Does Finasteride Cause Male Infertility?

Long-term data on fertility is lacking. What we know is that certain men may be more likely to suffer the effects of infertility if they already have fertility issues before taking Finasteride.⁶

For some patients, taking finasteride does affect their sperm quality and quantity making it more difficult to conceive. We advise speaking with a fertility specialist and stopping finasteride to ensure sperm counts and motility return to baseline levels.

Dr Roshan Vara, Hair Transplant Surgeon, The Treatment Rooms London

The risk in otherwise healthy men is low. The effects on semen are short-lasting and will likely return to normal after the medication is stopped.

Are Changes to Semen Reversible?

Changes seen to semen with finasteride use are reported to be reversible in most studies. There is no suggestion that any effects will be long-lasting on semen. Recovery towards your normal baseline should be seen within a few months of discontinuation.⁴

Can Finasteride Change the Appearance of Semen?

As discussed, finasteride may have an impact on semen volume. There is no established effect on visual appearance or thickness of semen. However, it is plausible that with reduced prostate fluid entering the semen, it may look more ‘watery’ than usual. 

That said, there is no reliable way to judge sperm count or quality based on appearance or consistency. That would require laboratory semen analysis.⁸

Can Finasteride Pass Through Semen?

Finasteride passes into the semen at minuscule amounts. A thousandth fraction of the 1mg dose may be present in each ejaculate.³

That said, it is recommended to wear a condom if your sexual partner is pregnant or likely to become pregnant and you are taking finasteride.⁹ This is because of the increased risk of birth defects caused by the action of finasteride.

Is There a Risk to a Pregnant Partner or Baby?

Finasteride is not recommended for use by women of child-bearing age due to risk in pregnancy. The hormonal changes brought on by the medication could potentially have adverse consequences for the developing foetus.³

If you have a pregnant partner or are looking to start a family, please seek the advice of a qualified medical professional. You will most likely need to stop taking finasteride before starting a family.

What Should You Do If You Are Trying to Conceive?

If you are trying to conceive, speak to the doctor who prescribed you finasteride. They will be able to guide you further. Do not stop or adjust treatment without specialist advice.

You may want to discuss the impact of finasteride on your fertility with a fertility specialist. If you are having difficulty conceiving, you may want to have your semen analysed to check for a cause and whether you should stop Finasteride.

Will it impact my sexual function?

Although it may impact semen volume, there should be no corresponding loss of pleasure or ability to have sex. Most people do not notice any difference. 

If you do encounter issues with sexual function, you should report it to your prescribing doctor as soon as possible. It is important that your well-being is prioritised and that any changes, if needed, be made to improve those symptoms.

When Should You Seek Medical Advice?

No treatment is perfect. It may be the case that you notice some adverse effects while taking finasteride. If you notice any of the following:^10,11

• a change in mood or suicidal thoughts
  
• A persistent reduction in ejaculate volume or force
  
• blood in your semen
  
• Testicular discomfort or swelling
  
• sexual adverse effects such as erectile dysfunction (ED) that is impacting your mental health

Then you should discuss this with your finasteride prescriber immediately.

The goals of treatment are to provide more benefit than harm. If that balance has shifted, you need to maintain communication with your doctor, who is there to help and guide you to find the best balance for your life goals and help you thrive.

Conclusion

It can be difficult to know whether or not finasteride is the right treatment for you. There are many things to consider with your doctor to make the right choice.

Finasteride is a widely used medication to help slow the progression of male pattern hair loss and is highly effective in doing so. However, it has some side effects to look out for. The final decision will be about balance. What matters is that the benefits to your life outweigh the potential risks. 

References

1. Kaufman KD, Olsen EA, Whiting D, Savin R, DeVillez R, Bergfeld W, et al. Finasteride in the treatment of men with androgenetic alopecia. J Am Acad Dermatol. 1998;39(4 Pt 1):578–589. doi:10.1016/S0190-9622(98)70007-6. 
2. Liu Y, Tosti A, Wang ECE, et al. Androgenetic alopecia. Nat Rev Dis Primers. 2025;11:73. doi:10.1038/s41572-025-00656-9.
3. Finasteride 1 mg film-coated tablets: Summary of Product Characteristics (2026). Electronic Medicines Compendium. Revised 7 March 2026. Available at: https://www.medicines.org.uk/emc/product/7068/smpc (Accessed: 23 July 2026). 
4. John K. Amory, Christina Wang, Ronald S. Swerdloff, Bradley D. Anawalt, Alvin M. Matsumoto, William J. Bremner, Susan E. Walker, Lynda J. Haberer, Richard V. Clark, The Effect of 5α-Reductase Inhibition with Dutasteride and Finasteride on Semen Parameters and Serum Hormones in Healthy Men, The Journal of Clinical Endocrinology & Metabolism, Volume 92, Issue 5, 1 May 2007, Pages 1659–1665, https://doi.org/10.1210/jc.2006-2203 
5. Pallotti, F., Senofonte, G., Pelloni, M. et al. Androgenetic alopecia: effects of oral finasteride on hormone profile, reproduction and sexual function. Endocrine 68, 688–694 (2020). https://doi.org/10.1007/s12020-020-02219-2 
6. Samplaski, M.K., Lo, K., Grober, E. and Jarvi, K. (2013) ‘Finasteride use in the male infertility population: effects on semen and hormone parameters’, Fertility and Sterility, 100(6), pp. 1542–1546. doi: 10.1016/j.fertnstert.2013.07.2000. 
7. Liu L, Zhao S, Li F, Li E, Kang R, Luo L, Luo J, Wan S, Zhao Z. Effect of 5alpha-Reductase Inhibitors on Sexual Function: A Meta-Analysis and Systematic Review of Randomized Controlled Trials.J Sex Med. 2016;13(9):1297-310. Epub 2016/08/01. [PMID: 27475241]
8. World Health Organization (2021) WHO laboratory manual for the examination and processing of human semen. 6th edn. Geneva: World Health Organization, section 2.4.2.1, p. 16. Available at: https://www.who.int/publications/i/item/9789240030787. 
9. National Institute for Health and Care Excellence (2026) Finasteride. British National Formulary. Available at: https://bnf.nice.org.uk/drugs/finasteride/ (Accessed: 23 July 2026). 
10. Bristol Laboratories Limited. (2026, May 7). Finasteride 1 mg film-coated tablets: Summary of product characteristics (PL 17907/0497). Medicines and Healthcare products Regulatory Agency. https://mhraproducts4853.blob.core.windows.net/docs/b7b9b2611152cfc058b9b27992a202edfd4a9cb5 
11. Medicines and Healthcare products Regulatory Agency. Finasteride and dutasteride – updated safety warnings for psychiatric side effects and sexual dysfunction [Internet]. Drug Safety Update. 2026 May 11 [cited 2026 Jul 23]. Available from: https://www.gov.uk/drug-safety-update/finasteride-and-dutasteride-updated-safety-warnings-for-psychiatric-side-effects-and-sexual-dysfunction