I have been told that gentamicin eyedrops should not be used for kittens because it contains a steroid. True?

There are two gentamycin drops that I have seen - one is just the antibiotic, the other is an antibiotic with a steroid. That second one is not generally the first thing that vets prescribe, and is generally reserved for eye infections with much inflammation. And generally yes, you want to avoid steroids with kittens but sometimes they can have eye infections so severe that the vet has no choice but to use a steroid to try to relieve the swelling.

I only work with humans, so I had to look this up for cats. From what I know about human physiology, I have a hard time imagining that it should not be used in kittens.

It does not contain any steroid ingredients. I can tell you that for sure.

When I researched it, I found that it is FDA approved for dogs and cats with no age limitations mentioned.

This sounds like an urban myth.

I looked through the prescribing information, and there are reasons you might choose a different drug in certain cases, but there is absolutely no basis for a blanket statement that gentamicin should not be used with kittens.

Unless you're planning to eat the kittens or their livers. There is some research suggesting that gentamicin residue can accumulate in the liver of calves treated with intravenous gentamicin, and nobody knows how long it takes for it to leave the liver.

I am extremely grateful to both Frank and JC for their efforts, both were extremely helpful answers and required thought and in one case, research. I couldn't really choose a "best" answer but finally picked the one that mentioned there are two drops available, one with steroids, and this is probably where the confusion came from. Both wonderfully helpful to me and thank you.