Side effects are rather rare with finasteride, and usually disappear when the therapy is discontinued. This is the opinion of the manufacturer. On the other hand, there are many patients who report sexual problems related to the use of finasteride and dutasteride. In this respect, this is a point that has to be looked at very critically and cautiously:

– Erectile dysfunction, i.e. a decrease in the function of the penis. During sexual intercourse one is no longer able to achieve or maintain an erection

– relatively frequent are also reductions in libido and volume of ejaculate

– Less frequent is the side effect of gynecomastia. this is a phenomenon when a man develops an abnormally large breast. even though it is medically no problem, it represents a psychologically serious problem for the men affected and can be a great strain

– one of the controversial applications of finasteride is the application to women. Due to its anti-androgen effect, it could be thought to have an effect against hair loss, but on the other hand the use of such preparations can hinder the formation of the sexual organs in the foetus. Therefore, there are only studies in women of infertile age

– there is evidence that finasteride may cause symptoms associated with depression. Some caution should be exercised here

– there are no side effects, but it should nevertheless be mentioned that finasteride is on the Anti Doping Agency’s list of banned substances. This is because the active ingredient can mask the use of steroids.

Details of sexual side effects

After a very detailed analysis of 17 randomized controlled clinical trials with 17,494 patients of finasteride, dutasteride or their combination, Liu et al. come to the conclusion that the side effects were not significantly changed in the application with constitutional hair loss. The vast majority of studies with a dosage of 1 mg show only a small difference in side effects compared to placebo.

With about 2-3% side effects, Finasteride is usually only slightly above the drug-free comparative treatment. Nevertheless, the question arises as to how this can be reconciled with the problem of reduced libido and erection problems, which is often so well known in practice. It can not be excluded that this is based on discussions in certain forums and in a study on the feedback of forum members (Irwig / However, these studies should be treated with great caution under objective criteria, as they are neither randomized nor blinded, but there are also some studies that show some caution.

In a study by Gubelin Harcha et al in which finasteride 1 mg is compared with various dutasteride strengths, a change in libido occurs in 6.7% of patients and impotence in 6.1% of patients – both significantly higher than with dutasteride 0.5 mg and placebo.

In summary, it can be said that the use of the products is safe overall and has a good relationship between effect and side effect. As is always the case with statistics, it should not be forgotten, however, that if you yourself belong to the approx. 3-6% of patients who are affected by side effects, the effects can be particularly serious on sexual life. In this respect, it has to be taken into account whether there are problems with medication and, accordingly, attempts are made to eliminate these symptoms by discontinuing the medication.


Liu L, Zhao S, Li F, Li E, Kang R, Luo L, Luo J, Wan S, Zhao Z.: Effect of 5a-Reductase Inhibitors on Sexual Function: A Meta-Analysis and Systematic Review of Randomized Controlled Trials. J Sex Med. 2016 Sep;13(9):1297-1310. doi: 10.1016/j.jsxm.2016.07.006. Epub 2016 Jul 27.

Fertig, R. M, Gamret, A. C, Darwin, E., & Gaudi, S. (2017). Sexual side effects of 5-a-reductase inhibitors finasteride and dutasteride: A comprehensive review. Dermatology Online Journal, 23(11). Retrieved from