I had a cat that only tried catnip once and then refused to go anywhere near it. I think it may have been because his first exposure was huge.

Can cats overdose on catnip?

I have never heard of a catnip overdose, but I think it is possible that your cat dislikes it because he'd had too much when he first tried it. It's like a kid who eats too much candy, gets sick, and then begins to avoid this particular candy altogether.

LOL! I've never heard of a cat overdosing on catnip! I bring stems of it in for mine and they shred it all over the place, but I never thought there would be a standard dose of it per se.