Cats love catnip. And it's perfectly safe - there's nothing in it that can harm your cat. If by some chance your cat was to eat a large amount of catnip, it could cause a mild tummy upset, but that's not likely to happen.Can dogs have it? The answer is yes, catnip is completely safe for dogs to ingest! The catch is that catnip has the complete opposite effect on dogs as it does on cats. While it acts as a very effective stimulant for cats, it is actually a sedative for dogs.