Most smokers become addicted to nicotine, a drug that is found naturally in tobacco.Cigarette smoke is a complex mixture of chemical compounds that are bound to aerosol particles or are free in the gas phase. Chemical compounds in tobacco can be distilled into smoke or can react to form other constituents that are then distilled to smoke. Researchers have estimated that cigarette smoke has 7,357 chemical compounds from many different classes .
Nicotine replacement medications, including patches, gum, lozenges, nasal spray and inhaler, can help relieve difficult withdrawal symptoms and cravings. It kills nearly 6 million people and causes hundreds of billions of dollars of economic damage worldwide each year. Between 2002 and 2013, past month use of any tobacco product among persons aged 12 or older decreased from 30.4 to 25.5 percent, and past month cigarette use declined from 26.0 to 21.3 percent . Past month cigar use decreased from 5.4 percent in 2002 to 4.7 percent in 2013. Research into nicotine's most predominant metabolite, cotinine, suggests that some, if not most, of nicotine's psychoactive effects may actually be mediated by complex interactions with cotinine, or perhaps even by cotinine alone rather than strictly by nicotine as conventionally thought.