It's a possible side effect of finasteride and as far as I'm aware its prevalence hasn't been established, but based on comments online, people are getting it. Yet it also seems that the vast majority of comments on finasteride sides by those concerned but not necessarily yet affected by finasteride are about things like ED, decreased ejaculatory volume, etc. Basically genitalia issues. I haven't started finasteride yet but am pretty sure that I already have a mild case of ED. Personally I don't see what the big deal is, unless someone is urgently trying for kids; but I bet most on finasteride aren't. I would take ED over man boobs any day, and am certain that any sane man would, which is why I'm surprised that almost every comment by the aforementioned regarding finasteride sides apparently has to do with having erection/ejaculation troubles. Have you seen stats on gyno prevalence, etc.?