Nicotine is an addictive substance found mostly in tobacco plants. In plants, it functions as an insecticide — poisoning insects that try to eat the plant. Humans, however, get very different effects from nicotine. It stimulates them, or makes them more alert. It relaxes them too. Unfortunately, nicotine is extremely addictive. The more someone uses it, the more they crave its effects. That makes it harder and harder to stop using it.
People take in nicotine in many ways. Many inhale it in smoke or vapor from cigarettes, cigars, pipes, hookahs or e-cigarettes. Others chew it in chewing tobacco. Almost 40 million adults in the United States smoke cigarettes. Another 4.7 million teens use a nicotine-containing product — usually cigarettes or vaping pods.
Some who are trying to quit smoking or vaping will use nicotine gum or skin patches. These give them a smaller dose of nicotine that might help make quitting for good a little easier.