I was wondering if anyone knew anything about the generic versions of birth control and their effectiveness. I was given a 4 month supply of cylessa, and when I got my prescription filled, it had changed to velivet. Apparently my insurance company allows the generic substitutes because they are cheaper...I was just wondering if they are any less effective or a different formula? I don't want to have to change...I have gotten used to the formula I am on and so far it's been working great. If anyone has some input, it would be greatly appreciated. Thanks!