Nicotine is an addictive drug. Smokers who crave it find it hard to go without having a cigarette. People who are under stress or feel nervous or bored often are at more risk of becoming addicted to nicotine.

Is nicotine the only reason people smoke cigarettes?
No. Smokers get hooked on the taste, smell and feel of cigarettes. Also, they link smoking with many activities.

Some people like to smoke when they are talking on the telephone with friends or when they are having a cup of coffee after dinner. Other people like to smoke at parties or when they are relaxing at home.

The combination of nicotine addiction and these kinds of strong mental links makes smoking a tough habit to break.

How does nicotine work?
Nicotine works on the brain and other parts of the nervous system. While a person is smoking, nicotine reaches the brain faster than drugs that enter the body directly through the veins. (For example, the brain feels the effects of nicotine faster than it feels the effects of a shot of heroin in the arm.)

When smokers breathe in smoke, they draw nicotine into their lungs. Then, their Bloodstream picks it up and it is quickly pumped by the heart right to the brain. Within just seven seconds the nicotine reaches the brain. This sudden burst of nicotine causes an instant "high." Some nicotine goes to other parts of the body. And if a woman is pregnant, this burst of nicotine also reaches the fetus through connecting blood vessels.

What are the effects of nicotine?
In large amounts, addictive drugs like nicotine, heroin and cocaine are poisons. For example, nicotine has been used to kill insects.

Nicotine makes the heart beat faster, increases the breathing rate and causes the body to use more oxygen. Nicotine causes other changes in the circulatory system, too. For example, blood vessels narrow. This can increase blood pressure.

Nicotine also appears to increase the tendency of the blood to clot and has been linked to diseases of the blood vessels and heart.

Why does smoking help people relax?
Nicotine can have different effects. It can act as an "upper" and speed up many body reactions. Or it can act as a "downer" and affect mood. How nicotine works depends on several things; the amount of nicotine in the body, the time passed since the last cigarette, stress level and even the time of day.

Early in the day nicotine acts as a stimulant to many people. Later in the day, it seems to act more as a sedative and helps people to relax.

Why aren't smokers satisfied with one or two cigarettes a day?
When people smoke cigarettes for the first time, the nicotine may make them feel sick to their stomach and dizzy. As they smoke more cigarettes, the unpleasant feelings go away, and they get used to the nicotine and like its "upper" effects.

Smokers often find they need a second cigarette, and another and another, in order to get the same feelings. After awhile, they find the number of cigarettes that keeps them satisfied. At that point, the person is physically addicted and will only feel comfortable when nicotine is in his or her system.

Why should cigarette smokers think about quitting?
One in four smokers dies early because of his or her smoking. Smokers die of heart disease, cancer and emphysema. At one time smoking seemed "cool," but it has become less and less desirable.

What's more, research shows that secondhand smoke, the smoke from other people's cigarettes, can harm the health of nonsmokers. Breathing in another person's smoke can cause many breathing problems in children and cancer and heart disease in adults.

The trend now is for public places and work places to go smoke free. This should help smokers make the move to quit and keep everyone's lungs healthier.

Cigarettes are so much a part of the American scene that many people think of them as "normal." They are easy to buy and inexpensive compared to other drugs.

But cigarettes aren't normal. They are very addictive and cause sickness and death. Their use is restricted in many places and it is illegal for minors to buy them in most parts of the U.S.