[Finasteride] is associated with adverse side effects that could become persistent after therapy discontinuation.

Finasteride is a steroid 5-alpha-reductase inhibitor, approved for the treatment of androgenetic alopecia and benign prostate hyperplasia. In some patients the treatment is associated with adverse side effects that could become persistent after therapy discontinuation, resulting in the so-called post-finasteride syndrome (PFS).

—A pharmacogenetic survey of androgen receptor (CAG)n and (GGN)n polymorphisms in patients experiencing long term side effects after finasteride discontinuation: International Journal of Biological Markers, Dec. 9, 2014