Tobacco is used in many forms, including cigarettes, cigars, pipe tobacco, chewing tobacco, and snuff. Cigarettes are the most common type of tobacco used by teens, followed by chewing tobacco and snuff. Studies of school age children indicate that initiation of daily smoking (not occasional use) is highest among junior high school students (about ages 12-14).

Many harmful ingredients in tobacco, such as nicotine, carbon monoxide, and hydrogen cyanide are absorbed into the body through the lungs. Nicotine, the addictive substance in tobacco, is so toxic that it has been used as an insecticide.

Tobacco acts both as a stimulant and a depressant. A beginning smoker will experience euphoria, lightheadedness, giddyness, dizziness, elevated heartbeat and respiration rates, and a tingling sensation in the hands and feet. A chronic smoker will suffer from a diminished sense of smell and taste.

Not everyone who begins smoking will become addicted; however, when users give up smoking, withdrawal symptoms such as restlessness, nervousness, sleeplessness, sweating, reduced heart rate and blood pressure, inability to concentrate, compulsive eating, headaches, and irritability can occur. These physical withdrawal symptoms last for about one to three weeks.

Medical problems associated with smoking tobacco are normally the result of long-term use. Some of the many health hazards of tobacco are heart disease, cancer, lung disease, obstructive pulmonary and bronchial disease, gum and jawbone deterioration, gastrointestinal disease, eating disorders, and allergic reactions. The use of smokeless tobacco, such as chewing tobacco and snuff, can be as dangerous as smoking, causing mouth lesions and cancer.