Smoking is an addiction. Tobacco products contain nicotine, a highly addictive chemical found naturally in tobacco plants.

Nicotine addiction has two components: physical and psychological. Research suggests that children and teens may be especially sensitive to nicotine, making it easier for them to become addicted. The younger the smoker, the more likely he or she is to become addicted. In fact, about three out of four high school smokers will become adult smokers.

Physical impact of nicotine
When a person smokes a cigarette or cigar, uses smokeless tobacco or an electronic nicotine delivery system (e-cigarettes), nicotine travels to the brain within seconds, where it quickly binds to nicotine receptors and eventually leads to a release of dopamine in the pleasure pathways of the brain. Once this happens, the smoker typically begins experiencing feelings of pleasure and calmness. However, these effects wear off soon, triggering an urge to use tobacco again so that the smoker can get those same feelings. With continued tobacco use, the brain may adapt by increasing its number of nicotine receptors, and the smoker will gradually need even more nicotine to feel satisfied.

Psychological impact of nicotine
The psychological addiction develops based on the connection between tobacco use and the activities a person engages in while using tobacco. For example, if a smoker enjoys coffee and a cigarette every morning for years, the two habits are likely linked in the brain, so even when the person no longer smokes, future cups of coffee may trigger an urge. After months or years of using tobacco, it may become part of a daily routine where the smoker is not even making a conscious decision to use tobacco.