Why Nicotine Is So Addictive

Most smokers say they want to quit, and most have tried at least once. If it were only a matter of willpower, far more would have succeeded on the first go. The reason they haven't is nicotine, and the way it weaves itself into everyday life.

Seconds from lungs to brain

When you inhale cigarette smoke, nicotine is absorbed through the large surface of the lungs and carried to the brain in a matter of seconds. That speed matters. Drugs that act fast are more likely to cause dependence, because the brain links the action (the puff) to the reward (the effect) almost instantly. A cigarette delivers that rapid hit ten or more times, and a pack-a-day smoker repeats the cycle well over a hundred times a day.

What nicotine does in the brain

Nicotine attaches to receptors in the brain called nicotinic acetylcholine receptors. This triggers the release of dopamine in the brain's reward system, the same system involved in food, sex and other drugs. It also affects other chemical messengers that influence mood, attention, stress and appetite. The result is a short-lived lift: a little more alert, a little calmer, a little less hungry.

With regular smoking the brain adapts. It grows more nicotine receptors and comes to expect a steady supply. When nicotine levels fall, often within an hour or two of the last cigarette, the brain is out of balance. You feel restless, irritable and edgy, and the next cigarette fixes it. This is why many smokers believe cigarettes relieve stress. For the most part they are relieving the stress of nicotine withdrawal, which the previous cigarette created. Studies have found that people's stress and anxiety levels tend to fall, not rise, a few months after they quit.

Three layers of addiction

Good quit plans tackle all three. Nicotine replacement or medicine takes the edge off the physical side. Planning and practice handle habits. New ways of coping deal with emotions. Our guide to ways to quit shows how the methods fit together.

Cues and triggers

Over years of smoking, the brain learns to associate cigarettes with hundreds of everyday cues: the smell of coffee, a phone call, the end of a meal, a glass of beer, the click of chips at a card table. Each cue can trigger a craving long after the physical withdrawal has gone. That is why ex-smokers sometimes get an urge out of nowhere on a night out months later. It's not a sign of failure; it's an old memory. More on handling them in cravings and triggers and, for nightlife specifically, casino and bar triggers.

Why it starts so young

In many countries, most adult smokers had their first cigarette as teenagers. The adolescent brain is still developing and appears to be especially sensitive to nicotine, which helps explain why habits formed early are so stubborn. This is one reason health bodies worry about young people using nicotine in any form.

Is nicotine itself what harms you?

Nicotine is what keeps people smoking, but it is not the main cause of smoking-related disease. Most of the damage comes from the tar, carbon monoxide and thousands of other chemicals in tobacco smoke, dozens of which are known to cause cancer. That's why medicinal nicotine, in patches, gum and other products, is considered far safer than smoking and is widely recommended to help people quit. It's not completely harmless, and it is still addictive, but swapping cigarettes for licensed nicotine replacement is a big step towards health. See nicotine replacement therapy explained.