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. 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.