I suppose the only real danger from Cat Nip that I ahve ever seen in the Years of having Cats is that they may become over stimulated and start fighting.
But other tahn that CatNip is good for Cats as it stimulates them,and I think sharpend thier sense.
And you can but Cat Nip at a Spice Importers ,fresh for a lot less than The Pet Food Stores Charge.
Cats love thier NIP!