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 Vaping Fact Sheet CardioSmart American College of Cardiology Vaping Harmless. Vape aerosol contains toxic chemicals like formaldehyde, arsenic, lead, chromium, and nickel. They damage lungs. They harm developing brains. They raise cancer risks. We Talking to Your Teen Who Vapes University of Rochester Medicine