Nicotine is a stimulant drug, found in tobacco products. Cigarette smoke contains more than 7000 chemicals, many of which are harmful. They include: carbon monoxide, tar, acetone, lead, mercury, chromium and cadmium, hydrogen cyanide, ammonia, polonium 210. Over 70 of these chemicals have been found to be carcinogenic (cancer-causing). Tobacco products include cigarettes, cigars, pipes, loose leaves and snuff. Usually it is smoked in cigarettes.