It all depends on the drug, etc. When I was given generic sleeping pill It didnt do shit. I could take 2 ambien and it wouldn't make me tired. When I mentioned it to the pharmacist he replied "oh, its in your head" so I told him that I wanted brand name from now on. Well, a few months later that same pharmacist told me that they stopped selling a few particular generic ambiens because paitents said they weren't working. I then had my "I told you so" moment. I know that a lot of manufacturers of brand names will also manufacture the generics. In fact when I was getting adderall, when they first went generic on the ER the pharmacist told me that I might as well save some money and get the generic as they came from the same factory as the brand. one week they make brand, the next they make generic. Just like the old Teva oxycontin. They were WORTHLESS!! but give me the ABG generics any day. So, It sometimes can be a real crap shoot when getting a new generic. I usually will do my homework before jumping to a generic...