Cigarette smoking can become an addiction in the same way as alcohol, tranquilizers and other drugs do.
Tobacco contains nicotine, a powerful addictive drug that enters the brain very quickly with each puff on a cigarette. The nicotine changes how your brain works, boosting your mood and making you feel calm and more alert. Over time, your energy level or mood can drop, causing you to crave a cigarette for another boost. The more you smoke, the more nicotine you need, which then leads to more smoking.