Fucidin H is an antibacteria and mild topical steriod cream and is safe to use on babies -- it is probably only harmful to cats if they licked it -- if your cat has an infected area such as from a wound or bite i would seek advice from the vet. if it is having an allergic reaction which is looking a bit infected then it is probably ok to use for a few days but no longer than 5 days Max (WE only say 7 for children 14 for adults)