Finasteride is the active ingredient in Propecia as well as Proscar, Fincar and all other generic Propecia-esque Finasteride-drugs. This essentially means that the effect of all these drugs is the same (with the same dosage), as the active ingredient is the same. The difference is in the fact that Propecia is developed by Merck specifically for targeting the treating of male pattern baldness, thus it has 1mg of Finasteride per pill.
The generic variants with the same active ingredient (Proscar and the others) have 5mg of Finasteride per pill and they are mainly used for Prostrate issues in men. But as the active ingredient is the same, people simply cut down those 5mg pills in fourths or fifths for 1.25mg or 1mg of Finasteride, thus being able to use the same pill for 4 or 5 days for the same effect. Cutting pills is easy, as you can get a pill-cutter from pharmacies for like a few bucks.
The reason people (including me) opt for the generic version is that - provided you can get it prescribed or ordered in legit form - you will have the same benefit for much cheaper!
To give you an example, I asked my doctor to prescribe me the generic Finasteride pill they sell in here in Finland, instead of official Propecia. The costs?
100 pills of Gefina (generic Finasteride, 5mg per pill) = 40$. These will last me 400 days, as I cut each pill in 4 parts. costs me 40$ for 400 days.
98 pills of official, brand-name Propecia = 306$ or so. As these pills only have 1mg of Finasteride in them, I could use them for 98 days. This means that for 400 days, I'd spend roughly 1220$ (98 days times 4, roughly).
Same effectiveness with either pill, whilst the other one costs me 40$ in 400 days and the other 1220$ in 400 days. Seems like a no-brainer to me. (Note that these prices are only for Finland, but the effect should be similar globally).
Hope this helped, best of luck.
