Post-finasteride syndrome

Finasteride, a 5α-reductase inhibitor, was approved in 1992 for the treatment of benign prostatic hyperplasia; a lower dose (1 mg) was approved in 1997 for male pattern baldness. A second 5α-reductase inhibitor, dutasteride, was approved in 2001 for benign prostatic hyperplasia. Emerging post-marketing reports of persistent depression and sexual side effects have led to growing concerns about the safety of 5α-reductase inhibitors and prompted product labelling changes in many regulatory jurisdictions.1234 Since 2008, at least 17 countries including the United Kingdom and the United States have warned prescribers of the potential for depression, sexual side effects, or both with finasteride.5

Post-finasteride syndrome is an ill defined and controversial syndrome associated with a constellation of sexual, physical, and psychological symptoms that develop during or after finasteride exposure and persist after discontinuation (box 1).35 The incidence of post-finasteride syndrome is unknown, as are the biological mechanisms, but we know that 5α-reductase inhibitors reduce synthesis of brain neurosteroids, which affect mood, cognition, and libido.36