Nicotine is one of the key ingredients of tobacco, and is one of the active components of tobacco smoke. In fact, it’s what gives tobacco smoke its very strong and pungent smell. It has a strong taste, which some describe as “acrid,” and though it is naturally a faint ylellow, it has a tendency to turn brown when it comes in contact with air. In its pure form, nicotine is oily and sticky. It has poisonous properties, and is sometimes used as a pesticide. However, the amount of nicotine used in cigarettes is kept at a low level of 2% to 7%.
Given all these properties, one wonders why smokers crave nicotine. That’s because nicotine is highly addictive. Though the health risks are well known (and are in fact printed in large letters on every pack of cigarettes) smokers have difficulty kicking the habit.
Smokers have a tendency to associate nicotine with its calming-yet-energizing effect—they report feeling alert, yet free of jitters. That’s because nicotine directly acts on the autonomic nervous system. However, it wreaks havoc on the rest of the body, particularly the respiratory system. For example, clinical tests show that at doses of 50 mg it can lead to respiratory failure and even paralysis. Lower doses, however, can cause a dip in blood pressure, palpitations, and nausea. Each cigarette contains about 3 mg of nicotine, and this is enough to constrict blood vessels and increase in heart rate. Nicotine has also been linked to the growth of tumors and heart disease.