7.5 months on propecia. Shedding 200 hairs/day. How common is it for finasteride to not work, in your clinical experience?

In my experience Propecia is effective in about 90 % of our patients.Are you taking brand name Propecia or generic(Finasteride)?If generic it might be worthwhile to switch to brand name.Shedding of 200 hairs per day is excessive so I do recommend a full evaluation by a Dermatologist or experienced Hair Restoration surgeon.Other possible adjuncts to prevent hair loss include Minoxidil (Rogaine),Low Level Laser Light therapy and PRP(Platelet Rich Plasma).

Propecia
works reasonably well for a large part of our patients when taken daily.  Some patients use minoxidil in addition to
Propecia as there is a slight additive effect. 
Another suggestion is using low level laser light therapy (LLLT).

About 13 % of users of finasteride will not achieve any benefit whatsoever. Shedding of 200 hairs after 7.5 months on the medications is unusual. A full evaluation by a dermatologist is advised.