My hairloss only became aggressive after taking finasteride. finasteride fried my hair, period. I had been slowly thinning and receding in the frontal third for a couple of years before starting finasteride. My crown and mid scalp had great density still. I had an above average head of hair with thick hair strands and an insanely thick donor area. Nine months on finasteride completely transformed my hair for the worse. I lost a ton of density and started balding in the areas that were fine, including on the sides and in the donor area. I was shedding these shredded looking white hairs that were almost invisible. Never shed hair that looked like that nefore finasteride.
It really pisses me off that going on twenty years with this drug that people deny that it can accelerate hairloss. And that useless a**h** Dr. Rassman? I spent hours looking at old posts from people trying to figure out why their hair got way worse on finasteride. He never once admitted the possibility. Just bizarre. He posts regularly on tressless (a forum no one should visit) still denying this. It's not like it's hard to understand. The mechanism is clearly understood.
I think accelerated hairloss from finasteride happens quite a bit. Who knows what the percentage is, but it is definitely high enough to acknowledge as a side effect.
finasteride for me was nothing but a baldness pill. No studies ever showed anyone worse off for taking it, which clearly is not the case. Propecia would have been DOA if they had said "Yeah, and, uh, one last thing, this awesome new hairloss drug, uh, speeds up hairloss in some men, but we don't know who will have that reaction". Never would have made it to market.