nicotine, commonly known as nicotine, is an alkaloid found in plants of the solanaceae family (genus solanum) and is also an important component of tobacco. nicotine can cause addiction or dependence (one of the most difficult addictions to break), people often have difficulty controlling themselves, and 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, death. tobacco often contains nicotine, which prevents many smokers from kicking the habit.