Did you know, not all cats respond to catnip?. Only about 70% of cats out there show a behaviorally difference around catnip.
Further, cats under the age of a few weeks old also are not attracted to catnip and some even show an aversion to it.
Catnip, which is a perennial herb in the mint family, contains a chemical called “nepetalactone” that is released when catnip is crushed. It is believed that this chemical mimics certain feline pheromones, specifically their theoretical facial pheromones.
When cats get a whiff of nepetalactone, most will start rubbing themselves against it, playing around with it, sometimes eating it, and generally will act quite bizarrely. However, not all cats actually respond to nepetalactone.