Tobacco contains the alkaloid, nicotine. Dried tobacco leaves are mainly smoked in cigarettes, cigars, pipe tobacco, and flavored shisha tobacco. They are also consumed as snuff, chewing tobacco, and dipping tobacco. Nicotine is one of the most heavily used addictive drugs and the leading preventable cause of disease, disability, and death. Cigarette smoking results in nicotine reaching the brain within just 10 seconds of inhalation.