There can be serious differences in how the different generics work for some people. The difference usually causes no problem, but some generics of some meds have caused such notorious problems that they have been pulled from the shelves. Wellbutrin xl was one of those. They don't have to go through exactly the same testing, which is exactly why the wellbutrin xl generic from one manufacturer was finally pulled. I was one of the unfortunate people who was given the generic brand that caused the problems. Not a good experience.

The VAST majority of generics are perfectly fine, but doctors are aware of certain generics that are prone to not work as consistently as the brand names, and it takes years to get those manufacturer's products pulled. That is why some pdocs will specify brand name required on certain prescriptions. Mine did on wellbutrin xl, and somewhere along the line the pharmacy didn't follow his directions and substituted the generic. I didn't call them on it and had no problems until one time they switched the generic manufacturer to save money. That switch ultimately destabilized me and ended up with an inpatient stay. Serious consequences just to save a few pennies.

The generic adderal xl is another generic that is prone to work inconsistently. My pdoc and I have had long discussions about this.

But again, the VAST majority of generics are fine, but it is important for us to note if our generic manufacturer changes and stay cognizant of any differences we note in how they affect us.