Is Finasteride Safe? Safety Profile and Risks

Male pattern hair loss affects up to 80% of men at some point in their lifetime. It often begins between the ages of 20 and 25, but tends to become more common and more noticeable with age.

To slow and reverse this hair loss, many men turn to treatments like finasteride. However, there are concerns about the potential side effects of finasteride and whether it’s safe.

It’s important you have all the facts. So, here we explore how it works, how safe it is (in the short and long term), who should not use the treatment and serious side effects of finasteride.

What is Finasteride?

Finasteride, more commonly known by the brand name Propecia, was originally developed to treat benign prostatic hyperplasia (BPH). This is the medical term for an enlarged prostate.

During clinical studies, researchers observed an unexpected side effect. Men taking finasteride reported reduced hair loss, with some also experiencing new hair growth. This finding led to further investigation, and finasteride was later approved as a treatment for male pattern hair loss.

Men with male pattern hair loss will take oral finasteride 1 mg daily, rather than the finasteride 5 mg tablets used for prostate conditions.

How Finasteride Works

Finasteride is a type of medicine known as a 5-alpha reductase inhibitor.

Finasteride works by blocking the enzyme 5-alpha reductase. This enzyme turns the hormone testosterone into another hormone called dihydrotestosterone (DHT), which can prevent your hair from growing.

By lowering the amount of DHT in the body, finasteride helps to slow hair loss. In some cases, it encourages new hair to grow.

Is Finasteride Safe for Long-Term Use?

Finasteride treatment is considered safe for long-term use in most men, provided you take it under medical supervision. Using it for longer doesn’t seem to make it any less safe.

There have been reports of breast cancer in some men taking finasteride, but this is rare. Speak to your healthcare provider if you get any changes in your chest area, like lumps, pain, swelling, or discharge from your nipples.

If you are considering long-term treatment with finasteride, it is important to keep checking in with your healthcare provider. They can assess whether the benefits still outweigh the risks and advise on whether to continue or to stop taking finasteride.

What Are the Serious Side Effects of Finasteride?

As with all medications, finasteride can come with side effects.

According to the Patient Information Leaflet, finasteride might cause sexual side effects, like erectile dysfunction. Uncommon side effects (that may affect up to 1 in 100 people) include:

• Being unable to get an erection
• Difficulty having an erection
• Having problems with ejaculation, including ejaculating less semen
• Less desire to have sex

Finasteride also has other side effects, although it’s unknown how often they occur. These include:

• Breast swelling or tenderness
• Pain in the testicles
• Blood in semen
• Palpitations (feeling your heartbeat)
• Anxiety
• Suicidal thoughts

The UK’s medicines regulator, the MHRA, advises patients who experience depression or suicidal ideation after taking finasteride to report these symptoms to their healthcare provider.

Most side effects of finasteride will stop as soon as you stop taking it and your body clears it out of your system.

If you have any concerns about potential side effects, speak to a healthcare professional before taking the medication. They can tell you whether finasteride is suitable for you.

Does Finasteride Affect Fertility?

Taking finasteride is not thought to affect fertility directly. However, sexual dysfunction, such as a reduced sex drive or erectile dysfunction, is a known side effect. This can indirectly make it harder to conceive.

Small amounts of finasteride (less than 0.001% of the 1 mg dose per ejaculation) can be found in semen. Studies in animals suggest the risk of this harming your unborn child is small. However, we recommend using a condom if your sexual partner is pregnant or likely to become pregnant.

If you are planning to have a child, it’s best to speak with your doctor or pharmacist. They can discuss whether you should continue or stop finasteride before trying to conceive. They will advise on the safest approach for your situation.

Who Should Not Take Finasteride?

Finasteride is not suitable for everyone. The following people should not use it:

• Women, especially if pregnant or planning pregnancy: Finasteride is only licensed for use in men. If a pregnant woman takes finasteride (or handles crushed tablets), it can cause abnormalities in the external genitalia of a male foetus.
• Children and adolescents: Finasteride is not approved for use in anyone under 18. Safety and effectiveness have not been established.
• Anyone allergic to finasteride or its ingredients: This applies to all medicines.

Men with liver disease will need to be cautious because finasteride is processed in the liver. It doesn’t mean you can’t take it. But doctors may avoid or closely monitor use in men with significant liver problems.

Can You Take Finasteride With Other Medicines?

Finasteride is not known to have any significant interactions with other medicines.

However, it is still important to let your healthcare provider know if you are taking finasteride. Your full medication history may be important to your care.

Is it Safe to Use Finasteride?

Yes, finasteride is generally safe for most men.

Serious side effects are uncommon and mostly improve as you continue taking finasteride or after you stop treatment. Before prescribing, your clinician will ask the necessary questions to ensure finasteride is appropriate for you.

Alternatives to Finasteride

If you are concerned about side effects but still want to treat hair loss, here are some alternatives:

Minoxidil solution or tablet

• It works by increasing blood flow to the hair follicle, resulting in increased hair growth.
• It has little to no effect on male hormones.
• It has proven to be an effective treatment for male pattern hair loss.

Dutasteride

• Like finasteride, dutasteride works by blocking the enzyme 5-alpha reductase. Dutasteride blocks two forms of this enzyme, while finasteride blocks one.
• Studies suggest dutasteride is more effective than finasteride for treating male pattern hair loss.
• It is unlicensed in the UK for hair loss, but licensed in South Korea and Japan.

Herbal remedies

• Little research, mostly anecdotal.
• One study found that rosemary oil showed hair growth stimulation comparable to 2% minoxidil.
• Unlikely to be effective at stopping male pattern hair loss.

Key Takeaways

• How Finasteride Works: Finasteride lowers levels of a hormone called dihydrotestosterone (DHT). This hormone can cause hair loss. By lowering the hormone, finasteride helps slow hair loss and may encourage regrowth in some men.
• Safety for Long-Term Use: Finasteride is generally safe for most men. Side effects are uncommon and usually resolve after stopping the medication.
• Who Should Avoid It: Finasteride is not suitable for women (especially during pregnancy). It’s also unsuitable for anyone under 18, or individuals allergic to the drug. Men with liver problems should use it cautiously under medical supervision.
• Fertility Considerations: Finasteride is not thought to directly affect fertility. But sexual side effects could make conceiving harder. Small amounts are present in semen, so we recommend precautions if a partner is pregnant or planning pregnancy. Always discuss with your doctor if planning to conceive.
• Drug Interactions: No significant interactions are known, but always inform your healthcare provider of all medications you are taking.
• Alternative Treatments: Options include minoxidil (topical or oral), dutasteride (not licensed in the UK for hair loss). Herbal remedies like rosemary oil have only anecdotal benefits. Effectiveness varies, so consult a healthcare professional before choosing an alternative.

References

Finasteride | Drugs | BNF content published by NICE. (n.d.). https://bnf.nice.org.uk/drugs/finasteride/.

Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial. (2015, February 1). PubMed. https://pubmed.ncbi.nlm.nih.gov/25842469/.

Male pattern hair loss (male androgenetic alopecia) | Health topics A to Z | CKS | NICE. (n.d.). https://cks.nice.org.uk/topics/male-pattern-hair-loss-male-androgenetic-alopecia/.

Website, N. (2024, September 10). Common questions about finasteride. nhs.uk. https://www.nhs.uk/medicines/finasteride/common-questions-about-finasteride/.

Zhou, Z., Song, S., Gao, Z., Wu, J., Ma, J. and Cui, Y. (2019). The efficacy and safety of dutasteride compared with finasteride in treating men with androgenetic alopecia: a systematic review and meta-analysis. Clinical Interventions in Aging, Volume 14, pp.399–406. doi: https://doi.org/10.2147/cia.s192435.

S. Prahalada, Tarantal, A.F., Harris, G.F., Ellsworth, K.P., Clarke, A.P., Skiles, G.L., Mackenzie, K.I., Kruk, L.F., Ablin, D.S., M. Cukierski, Peter, C.P., Vanzwieten, M.J. and Hendrickx, A.G. (1997). Effects of finasteride, a type 2 5-alpha reductase inhibitor, on fetal development in the rhesus monkey (Macaca mulatta). Teratology. doi: https://doi.org/10.1002/(sici)1096-9926(199702)55:2%3C119::aid-tera1%3E3.0.co;2-z.

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