As the actual leaf of the nepeta cataria plant, catnip leaf is a true "herb" (unlike other natural plant extracts such as roots, seeds, flowers and bark that are marketed as organic bulk herbs and while having possible healthful effects, are not actually "herbs" in the technical sense.

While humans may find dried nepeta cataria leaves to be an effective way to soothe the effects of an upset stomach when taken as an infusion, to their pet felines, catnip leaf is in fact not a medicinal herb but a narcotic. Felines have a sense of smell that is far more developed than that of humans - by a magnitude of several million. In fact, it has been suggested that felines perceive scent in the same way that humans perceive color. Just as certain wildcrafted herbs can cause humans to have visual hallucinations, so too does catnip leaf cause your tabby to experience olfactory hallucinations - which, if the typical cat response is any indication, are highly pleasurable, but ultimately harmless.