If you don't vape, don't start. Most e cigarettes contain nicotine, which is highly addictive and harmful to your health, especially for teens, young adults and those who are pregnant. Learn more about Teens say they don't vape, they 'Juul.' That makes the activity hard to track Los Angeles Times Exploring the Safest Vape Pens and Healthiest Alternatives 3 new vapes raise health concerns UW CTRI UWMadison