Yes, my daughter was on a generic medication for a year. I transferred it to Costco b/c there meds are less expensive. Costco had the same generic medication, but different manufacturer. She had terrible problems immediately. We gave it a few days, but I then transferred it back to Walgreens and she is now fine. The pharmacists say there is not enough of a difference b/w the generics to do this. It was too much of a coincidence here! As I said, once she switched back to the original generic she was fine. I am paying more, but at least it is less than the brand name. Hope this helps.