Cats can eat fresh catnip leaves, and many cats prefer this form,” notes Dr. Whittenburg. “Though cats are true carnivores, many kitties enjoy munching on greens from time to time, and catnip can provide a fun way to allow them to do so. Offer fresh catnip in moderation and only as an occasional treat.” The only real hazard of catnip may be the risk of injury while they are feeling wild. “Catnip of all forms is generally considered safe. Aside from mild gastrointestinal upset, the only reported issues come from kitties being injured while getting a little too crazy playing,” adds Dr. Whittenburg. “Catnip has varying effects on cats, hardly affecting some while making others go nutty with the zoomies. Cats playing with catnip should be in a safe environment and always be supervised.