Tobacco was recognised by Europeans as a medicine soon after it was first imported from the New World, and tobacco smoke was used by western medical practitioners as a tool against cold and drowsiness. During the early 19th century the practice fell into decline, when it was discovered that the principal active agent in tobacco smoke, nicotine, is poisonous. A tobacco smoke enema was employed by the indigenous peoples of North America to stimulate respiration, injecting the smoke with a rectal tube