How common are side effects of finasteride?

Let’s start with the most important fact: the vast majority of men who use finasteride experience no side effects at all. In large clinical trials, reported side effects were comparable to those seen with placebo - a sugar pill with no active ingredient¹. Approximately 96–98 out of 100 men experience no adverse effects, and among those who do, symptoms are usually mild and temporary².

Context is important: in clinical studies, finasteride has shown a side-effect profile comparable to placebo. In this respect, finasteride performs comparably to - or even better than - many commonly prescribed medications. It has been approved by health authorities worldwide and has been used safely for decades³.

The question is not whether side effects can occur - this is true for any medication - but how likely they are, how severe they are, and what can be done about them. Let’s look at that honestly and comprehensively.

What are the most common side effects of finasteride?

The most frequently discussed side effects of finasteride are sexual in nature. This is logical: finasteride lowers DHT, a hormone that also plays a role in sexual function. Here are the concrete figures from clinical studies¹:

Reduced libido and erectile dysfunction

These occur in 1–2% of users, only slightly more often than in men receiving placebo¹. It’s important to note that such symptoms can also be caused by stress, fatigue, or other non-medication-related factors.

Ejaculatory disorders: rarely reported

A small number of men report reduced ejaculation volume. These effects are more commonly associated with higher doses (used for prostate conditions) than with the 1 mg dose prescribed for hair loss⁵.

What you should know about these side effects:

• They are usually mild. Often the changes are subtle - noticeable to some men and barely perceptible to others.

• They are often temporary. Many men find that side effects resolve within weeks or months, even while continuing finasteride².

• They resolve after discontinuation. If you stop finasteride, side effects typically disappear within weeks to months⁴.

• The placebo comparison is critical. The fact that 2.1% of men in the placebo group also reported side effects highlights how strongly expectations and psychological factors can influence sexual function.

Less common side effects

In addition to sexual side effects, there are a few other possible adverse effects, which occur even less frequently:

Gynecomastia (breast tenderness or swelling)
Occurs in fewer than 1% of users. This is due to a slight shift in hormonal balance. It is usually mild and resolves after stopping the medication³.

Temporary effects on fertility
In rare cases, there are reports of temporarily reduced sperm quality or reduced fertility during use. This is important to know if you wish to have children. These effects are usually reversible: when stopping finasteride, sperm quality typically recovers within a few months³. Discuss with your doctor whether finasteride is suitable if you want to conceive children in the near term.

Allergic reactions
Skin rash, itching, or swelling are extremely rare. These reactions can occur with any medication and are not specific to finasteride.

Testicular pain
Some men report mild testicular discomfort. This occurs in fewer than 1% of users and is usually temporary³.

Mood changes or depression
There have been reports of mood changes. Scientific evidence for a direct causal relationship is limited, but awareness is important. If you experience depressive symptoms, discuss this with your doctor⁵.

It’s important to emphasize: all of these side effects are rare. The vast majority of men experience no noticeable effects at all.

Is finasteride safe long-term?

An important question: is finasteride safe for long-term use? The good news is that multiple studies confirm that it is. Research spanning 5 to 10 years shows that finasteride continues to be well tolerated⁶.

Interestingly, the incidence of side effects appears to decrease with long-term use. In one study, the rate of reported side effects dropped to less than 0.3% in men who used finasteride for five years². This suggests that the body may adapt to the medication over time.

What happens if you stop finasteride?

If you decide to stop finasteride - for any reason - it’s useful to know what to expect.

Side effects usually resolve quickly
For most men who experience side effects, symptoms resolve within a few weeks to three months after stopping. Finasteride leaves the bloodstream within approximately 5–6 hours, but it can take several weeks for DHT levels to fully normalize⁴.

Hair loss returns
Finasteride is a treatment, not a cure. Once you stop, DHT production resumes and hair loss typically returns within 6–12 months, progressing to the level it would have reached without treatment⁴. Any hair regrowth achieved is gradually lost.

No need to taper
Unlike some medications, finasteride does not require gradual tapering. You can stop immediately without withdrawal symptoms or rebound effects⁴.

Restarting is possible
If you stop and later decide to restart, you can do so. Finasteride will work again as before, although it typically takes 3–6 months to see results again.

What can you do if you experience side effects from finasteride?

If you experience side effects, don’t panic and stop immediately. Several options can be discussed with your doctor:

1. Give it time

Many side effects are temporary and resolve on their own within weeks. If symptoms are mild, patience may be worthwhile⁵.

2. Consider a lower dose

Some doctors recommend starting with a lower dose (e.g. 0.5 mg instead of 1 mg) to assess tolerance. The dose can be increased later if needed⁵.

3. Try a short break

For some men, taking short breaks (e.g. a few days per week) may help. This approach is not formally studied and should only be done in consultation with a doctor.

4. Consider topical finasteride

Topical finasteride, applied directly to the scalp, may result in fewer systemic side effects because less of the drug enters the bloodstream. This is a relatively new and promising option³.

5. Switch to alternatives

If finasteride truly isn’t suitable, alternatives such as minoxidil are available. Minoxidil works differently - by stimulating blood flow rather than blocking DHT - and has a different side-effect profile, mainly local skin irritation rather than sexual effects³.

6. Stop if necessary

If side effects are severe or persistent, discontinuation is always an option. Always discuss this with your doctor first.

The importance of medical supervision
At Menkind, registered doctors are available to guide you. They can help you find a strategy that works or suggest alternatives if finasteride is not suitable. Medical supervision is essential - do not experiment with dosages on your own.

Conclusion

For the vast majority of men, finasteride is a safe and well-tolerated medication. Approximately 96–98% of users experience no side effects at all¹. Among those who do, side effects are typically mild and often temporary².

The most common side effects are sexual in nature and occur in 1–2% of users, only slightly more often than placebo. Long-term studies over 5–10 years confirm that finasteride remains safe with prolonged use⁶.

Knowledge is power. Understanding potential side effects - and how rare they are - allows you to make an informed decision. And if side effects do occur, there are concrete solutions and alternatives available.

Unsure whether finasteride is right for you? The doctors at Menkind can provide personalized advice and work with you to develop a treatment plan that fits your needs. 

References

1. Mcclellan, K. J., & Markham, A. (1999). Finasteride: a review of its use in male pattern hair loss. Drugs, 57(1), 111–126. https://pubmed.ncbi.nlm.nih.gov/9951956/

2. Hirshburg, J. M., Kelsey, P. A., Therrien, C. A., et al. (2016). Adverse effects and safety of 5-alpha reductase inhibitors (finasteride, dutasteride): A systematic review. The Journal of Clinical and Aesthetic Dermatology, 9(12), 56-62. https://pubmed.ncbi.nlm.nih.gov/27672412/

3. Fertig, R. M., Gamret, A. C., Darwin, E., & Gaudi, S. (2017). Sexual side effects of 5-α-reductase inhibitors finasteride and dutasteride: A comprehensive review. Dermatology Online Journal, 23(11). https://pubmed.ncbi.nlm.nih.gov/29447628/

4. Diviccaro, S., Melcangi, R. C., & Giatti, S. (2019). Post-finasteride syndrome: An emerging clinical problem. Neurobiology of Stress, 12, 100209. https://pubmed.ncbi.nlm.nih.gov/32435662/

5. Mysore, V. (2012). Finasteride and sexual side effects. Indian Dermatology Online Journal, 3(1), 62–65. https://pubmed.ncbi.nlm.nih.gov/23130269/

6. Yanagisawa, M., Fujimaki, H., Takeda, A., et al. (2019). Long-term (10-year) efficacy of finasteride in 523 Japanese men with androgenetic alopecia. Clinical Research and Trials, 5(5). https://www.oatext.com/pdf/CRT-5-273.pdf