Tobacco dependence and withdrawal syndromes are classified as substance use disorders under the World Health Organization International Classification of Diseases (ICD 10). The American Psychiatric Association has come to similar conclusions in its Diagnostic and Statistical Manual of Mental Disorders (DSM IV), although it uses the terms 'nicotine dependence' and 'nicotine withdrawal'. The more common general term used to describe these diseases is addiction. Official recognition of smoking as a dependence is important in encouraging governments to offer treatment to smokers.

The most widely used classifications of substance dependence are the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM IV), and the World Health Organization's International Classification of Diseases (ICD 10). Nicotine and smoking meet both of these criteria for substance dependence (Royal College of Physicians, 2000, page 87). The Royal College of Physicians report concluded: "It is reasonable to conclude that nicotine delivered through tobacco smoke should be regarded as an addictive drug, and tobacco use as the means of nicotine self-administration."
All leading experts and public health organizations in the US and the international community with expertise in tobacco or drug addiction now recognize that nicotine is addictive (eg USDHHS, 1988; RCP 2000). It is the nicotine in tobacco products that sustains tobacco use and makes it difficult for many smokers to stop smoking even when faced with serious medical problems. Cigarette manufacturers have exploited this weakness and capitalized on the known addictive nature of smoking in order to profit by selling their products to consumers (eg Hurt & Robertson, 1998).

American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders. 4th edition. Washington: American Psychiatric Association. 1995.
Hurt RD, Robertson CR. Prying open the door to the cigarette industry's secrets about nicotine - The Minnesota Tobacco Trial. JAMA 1998; 280: 1173-1181.
Royal College of Physicians. Nicotine Addiction in Britain. A report of the Tobacco Advisory Group of the Royal College of Physicians. London: Royal College of Physicians. 2000.
http://www.rcplondon.ac.uk/pubs/wp_nicotine_summary.htm
US Department of Health and Human Services. The health consequences of smoking: nicotine addiction. A report of the Surgeon General. Washington, DC: Government Printing Office . 1988.
http://www.cdc.gov/tobacco/sgr/sgr_1988
World Health Organization. The ICD-10 classification of mental and behavioural disorders. Geneva: World Health Organization. 1992.