I was prescribed Norco for spinal surgery and it apparently gave me an allergic reaction in the form of a rash. I didn't realize this was just a brand name for vicodin until now. I have taken vicodin in the past with no problems. In both cases, it was generic that I've taken. However, I was taking the norco quite frequently after surgery and the vicodin I would only take as needed for back pain the advil and tylenol wouldn't relieve after a couple of days Would this be the reason for the difference in reactions or would it be something else?