Fresh catnip is thought to be easier on your cats mouth. According to the Pet Poison Helpline catnip is not toxic for cats and is safe to consume. Whilst most of the behavioral changes come when a cat smells catnip its perfectly safe for a cat to eat catnip.
It contains no toxic substance. Some cats become super playful while others become. So you do not have to worry about food poisoning while giving catnips to cats. If by some chance your cat was to eat a large amount of catnip it could cause a mild tummy upset but thats not likely to happen.