As is true for many other addictive substances, repeated exposure to nicotine results in the development of tolerance -- the condition in which larger amounts of a substance are required to produce the same effect.
just the facts
Approximately 90 percent of all smokers, even those who start out smoking only occasionally, eventually become regular daily smokers. (1)
Sources 1. Grunberg, N. Understanding the facts about nicotine addiction. The Brown University Digest of Addiction Theory and Application 1999;18(6).
explanation
The human body processes and eliminates nicotine relatively quickly; the drug only stays in the body for a few hours. Therefore, some tolerance to nicotine is lost overnight. Smokers often say that the first cigarettes of the day have the strongest effect and that later cigarettes seem weaker. This happens because smokers build up a short-term tolerance to nicotine over the course of a day and lose some of that tolerance overnight.
Tolerance is also important over the long term. Because people develop a tolerance to nicotine, very few people can smoke just a little for a long period of time.
You probably know some teenagers who smoke only occasionally, or who smoke only one or two cigarettes a day. In most instances, these are people who have started smoking only recently. These new smokers may tell you that smoking only a little is comfortable for them and that they don't plan to increase the number of cigarettes that they smoke. But if you come back a year from now and ask the same people about their smoking habits, you will find that most of them have become regular, daily smokers and that the number of cigarettes that they smoke has increased. Approximately 90 percent of all smokers, even those who start out smoking only occasionally, eventually become regular daily smokers. (1)
