cats from shelters often have an upper respiratory infection. (mine did). The medicine is for that....but, if I understand it correctly, it does not cure the cold, it helps prevent further (worse) conditions from forming. You know, while their defences are low, they could get an different kind of infection. I would say she needs to let it run its course (just like you and I can't CURE a cold). But most importantly, make sure she does not get worse. [in other words, keep and eye on her]