Nicotine is a substance found naturally in tobacco. It is highly addictive – as addictive as heroin or cocaine. Over time, a person becomes physically dependent on and emotionally addicted to nicotine.8
When you smoke, inhaled nicotine is carried deep into your lungs. There it is absorbed quickly into the bloodstream and carried throughout your body.8
Inhaled nicotine moves into the brain within seconds (drug levels peak within 10 seconds of inhalation).5,12 Rapid rates of absorption and entry into the brain cause a strongly felt “rush” and reinforce the effects of the drug.13
By inhaling tobacco smoke, the average smoker takes in 1–2 mg of nicotine per cigarette.
A typical smoker will take 10 puffs on a cigarette over a period of 5 minutes that the cigarette is lit.
Thus, a person who smokes about 1 pack of cigarettes (20 cigarettes) daily gets 200 “hits” of nicotine to the brain each day.5
Nicotine induces pleasure and reduces stress and anxiety.8,13 However, the acute effects of nicotine dissipate quickly, as do the associated feelings of reward.5 This makes the smoker want to smoke again. and to continue dosing to maintain the drug’s pleasurable effects and prevent withdrawal.5,8
After a while, the smoker develops a tolerance to nicotine. Tolerance means that it takes more nicotine to get the same effect that the smoker used to get from smaller amounts. This leads to an increase in smoking over time.8
Smokers use nicotine to control mood and tend to take in the same amount of nicotine from day to day to keep the level of nicotine within a comfortable range and achieve the desired effect.13
When smokers try to cut back or stop smoking, the lack of nicotine leads to withdrawal symptoms.8
These symptoms may begin within a few hours after the last cigarette, quickly driving people back to tobacco use. Symptoms peak within the first few days of smoking cessation and usually subside within a few weeks. For some people, however, symptoms may persist for months.5
Withdrawal symptoms can include the following8
- Feelings or frustration, impatience and anger
- Sleep disturbances
- Increased appetite
- Weight gain
- Chest tightness
- Cough, dry mouth, sore throat, and nasal drip
- Constipation and gas
The basis of nicotine addiction is a combination of positive reinforcements, such as enhancement of mood and mental or physical functioning, and avoidance of withdrawal symptoms when nicotine is not available.13
When a person who is addicted to nicotine stops smoking, the urge to resume is recurrent and persists long after the withdrawal symptoms dissipate.
With regular smoking, the smoker comes to associate specific moods, situations, or environmental factors — smoking-related cues —with the rewarding effects of nicotine. Typically, these cues trigger relapse.
Smokers usually take a cigarette after a meal, with a cup of coffee or an alcoholic drink, or with friends who smoke. When repeated many times, such situations become a powerful cue for the urge to smoke.
Aspects of smoking itself — the manipulation of smoking materials, or the taste, smell, or feel of smoke in the throat — also become associated with the pleasurable effects of smoking.
Even unpleasant moods can become conditioned cues for smoking: a smoker may learn that not having a cigarette provokes irritability and that smoking provides relief. After repeated experiences like this, a smoker can sense irritability from any source as a cue for smoking.
The association between such cues and the anticipated effects of nicotine, and the resulting urge to use nicotine, constitute a form of conditioning. The desire to smoke is maintained, in part, by such conditioning.
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