Catnip was cultivated for cats by the classical Greeks and Romans and by 1265 it was a familiar herb of kitchen gardens in England. During the early medieval period the leaves and young shoots are known to have been used as a seasoning in the kitchen. In 15th century England, catnip leaves were used for rubbing meats before cooking, and also sprinkled in mixed green salads. Before modern Chinese tea became widely available, catnip tea was frequently consumed. Catnip is best known for inducing a euphoric response in cats.
Cats purr contentedly, tear with delight, and roll in ecstasy on the crushed leaves of catnip.
The response of domesticated cats to catnip has been extensively studied. Any branches of catnip that have been bruised or broken will emit the catnip chemicals. The cats sniff, then lick and chew while shaking their heads, followed by chin and cheek rubbing and a head over roll and body rubbing. Kittens less than 2 months old do not react and some cats do not react until after 3 months old. The Nepetalactone chemicals responsible for the intoxication of cats seem to be similar to the natural sedative in Valerian, supporting the traditional use of catnip for humans as a mild tranquilizer and sedative.