What’s the Prevalence Of Sexual Side Effects From Finasteride?
Does finasteride lower libido? The true incidence of the sexual side effects of finasteride remains up for debate. Finasteride is the world’s best-studied hair loss drug. Over the past 30 years, it has been clinically tested in over 30,000 men – with dozens of randomized, double-blinded, placebo-controlled studies converging on relatively consistent efficacy and safety profiles.
While finasteride is generally well-tolerated, some users have reported sexual side effects after starting the drug. These reports are well documented in the clinical literature. However, their prevalence varies greatly depending on the study referenced.
In well-controlled clinical studies lasting 1-5 years, the incidence of these reports is generally under 7%, with 3-4% of people in the placebo group (sugar pill group) also reporting reductions to libido.[1]https://pubmed.ncbi.nlm.nih.gov/30206635/ In fact, one randomized, double-blinded, placebo-controlled clinical trials in ~2,000 men showed – over one year – that 1 mg daily of finasteride led to reduced libido in 1.8% of users versus 1.3% in the placebo group.[2]https://www.sciencedirect.com/science/article/pii/S0022202X15529357
This seems to indicate the risk of sexual side effects from finasteride is very low. However, other (smaller) clinical studies have put the incidence of sexual side effects as high as 25-30%. It is important to note that these smaller studies are generally of lower quality, so their results should be interpreted with caution.[3]https://pubmed.ncbi.nlm.nih.gov/17655657/ Nonetheless, these studies and the side effects they mention do exist.
Having combed through nearly all the available literature on the subject, we estimate the true incidence of noticeable sexual side effects for finasteride users likely hovers around 3-15%.
Why Does It Seem Like Everyone Online Says Finasteride Lowers Libido?
While side effects from hair loss drugs do occur, their perceived prevalence is often overstated on natural health websites and online forums. There are (at least) two reasons why:
- Financial incentives. Many natural websites fearmonger over hair loss drugs because they want to sell people natural alternatives – supplements and serums – that they claim are free of sexual side effects (which often isn’t true).
- The “Yelp Effect”. The Yelp Effect explains why a restaurant is far more likely to receive reviews from patrons who are dissatisfied (rather than happy) with their experience. Anger motivates us to take action more than contentment does. The same applies to FDA-approved drugs on hair loss forums (especially in online spaces like HairLossTalk and Reddit, where anonymity is preserved).
Can We Reduce the Risk of Finasteride’s Sexual Side Effects?
Yes. There are strategies to potentially reduce the risk of finasteride’s sexual side effects, while also still regrowing hair. These strategies include the following:
- Reduce the dose. As a hair loss drug, finasteride is typically prescribed orally at 1mg daily. However, there is evidence that 0.2mg orally daily is nearly just as effective at improving hair counts.[4]https://pubmed.ncbi.nlm.nih.gov/10495375/ This dose also simultaneously reduces total drug exposure by 80%. For many people, this coincides with a reduction in perceived side effects.
- Try a topical formulation. Studies show that – when formulated properly – topical finasteride may reduce the risk of side effects by 30-90%. One 16-month study on 0.005% topical finasteride demonstrated significant hair improvements, no drug-associated side effects, and no impact on blood hormonal levels.[5]https://www.tandfonline.com/doi/abs/10.3109/09546639709160517 This suggests that, at this dose, there is not enough leakage of finasteride from the scalp into the bloodstream to appreciably alter hormonal profiles – at least in the men and women in this study (though some people inside our membership have reported a different experience).
- Try intradermal delivery methods. Also known as mesotherapy, intradermal delivery methods inject finasteride into the scalp. But rather than use finasteride, consider using another 5-alpha reductase inhibitor: dutasteride. Evidence suggests that scalp injections of 0.01% x 1-2 mL of dutasteride – once every 1-3 months – do not appreciably alter serum hormones, nor do they result in any reported sexual side effects. They do, however, still lead to statistically significant hair improvements. Mesotherapy is more commonly done with dutasteride than finasteride, as dutasteride has a longer half-life (days-to-weeks versus 5-7 hours). This means fewer mesotherapy sessions are required to lower scalp tissue DHT (the hormone lowered by finasteride) for sustained periods.
For topical formulations and intradermal injections, testing personal blood levels of DHT before and during treatment can offer peace of mind. By quantifying the exact changes to serum DHT levels, it’s possible to see just how much topical finasteride (if any) is going systemic. In general, DHT fluctuations smaller than 20% are considered biologically insignificant. For more information on how to test serum DHT, look inside our ultimate guide to finasteride treatment.
So, consider the data first and foremost before giving up entirely on finasteride. It’s by no means guaranteed that finasteride lowers libido. Regardless, there are ways to leverage the power of this effective drug and simultaneously mitigate its risks.
Rob English is a researcher, medical editor, and the founder of perfecthairhealth.com. He acts as a peer reviewer for scholarly journals and has published five peer-reviewed papers on androgenic alopecia. He writes regularly about the science behind hair loss (and hair growth). Feel free to browse his long-form articles and publications throughout this site.