Nicotine is an alkaloid derived from the tobacco plant (Nicotiana tabacum). It has pharmacological properties as a nicotinic cholinergic receptor agonist. It is a highly addictive substance found in tobacco products (cigarettes, cigars, chewing tobacco, electronic cigarettes [e-cigarettes], etc) as well as some smoking cessation aids.

In 2017, 14% of adults in the United States were currently smoking cigarettes. This showed a decline in cigarette use from 2005, when 20.9% of American adults smoked. Cigarette smoking was the highest among American Indians / Alaskan natives, at 24%. In that same year, 19.6% of high school students used tobacco products. The most commonly used nicotine-containing products among this demographic were e-cigarettes, with 11.7% of high school students using them. Cigarette use has steadily declined over the years, but there has been a marked increase in use of e-cigarette products in adolescents and young adults.

The immediate effects of nicotine use include relaxation and increased alertness. However, the use of tobacco products has other negative long-term effects on health. Smoking is the number one risk factor for lung cancer worldwide. Smoking also increases an individual's risk for developing hypertension, atherosclerotic cardiovascular disease, myocardial infarction, stroke, and several other malignancies. Secondhand smoke has known health effects as well; it can worsen asthma and increases the frequency of recurrent respiratory infections.

Smoking during youth has been shown to increase risk for adult cardiovascular events, including death, before the age of 60.

Related topics: nicotine stomatitis, tobacco staining of nails, e-cigarette or vaping product use-associated lung injury (EVALI)