Cannabis smoking. Silhouetted man smoking cannabis through a pipe. Cannabis is a drug made from the leaves of the hemp plant, Cannabis sativa. The drug is placed in the bowl at the top of the pipe and lit. By inhaling through one of the mouth- pieces, a user draws smoke from the bowl though a vessel containing water at the base of the apparatus. This cools the hot smoke of the burning cannabis, making it more pleasurable to inhale. The effects of cannabis on the user can include mental relaxation, accelerated heart rate, perceived slowing of time and heightened senses of taste, touch, hearing and smell. Prolonged use can lead to psychological problems and lung damage.