The kitten's immune system needs to fight off the cold because it's caused by a virus and no medicine will help there. However, what you have to be concerned about is secondary infections caused by the virus, and that's why most vets will use antibiotics. I have kittens also and they've had to be on antibiotics for weeks because their eyes were very affected by the cold virus. The calici virus (fortunately my kittens didn't get that one), which is one virus that can cause colds, can affect the eyes to the point of loss.