Nicotine, commonly known as nicotine, is an alkaloid found in Solanaceae plants (Solanum) and is also an important component of tobacco. Nicotine can make people addicted or dependent (one of the most difficult drug addictions to quit), and people usually find it difficult to restrain themselves. Repeated use of nicotine also increases heart rate and blood pressure and reduces appetite. Large doses of nicotine can cause vomiting and nausea, and in severe cases, people can die. Nicotine is usually contained in tobacco, which makes it difficult for many smokers to quit smoking.