How do cats react to catnip and matatabi, and how should I use them properly?

Quick answer

The compound 'nepetalactone' in catnip and matatabi (silver vine) stimulates a cat's sense of smell, producing temporary euphoria and stress relief. Kittens under 6 months old and some individual cats may not respond at all. Giving it too often builds tolerance and reduces interest, so once or twice a week sprinkled on a toy is about right.