My cat has a mild cold?

Cats can develop chronic upper respiratory infections if one is not caught and treated as soon as possible. I would never take medical advice from someone over the internet - it would be best if you could bring the cat into the vet to have them diagnose the cat and prescribe it the medication it needs. I will say that I have used a medication on one of my cats for another one who contracted the same eye infection without first going to a vet and it did clear her symptoms. If I were you and couldn't get to the vet I would probably give my cat the medication, as long as it wasn't expired, but this is not good advice and a vet would be the best option.