E-cigarettes contain nicotine vapor but not tobacco or harmful chemicals. They don't produce secondhand smoke like cigarettes. While e-cigarettes are safer than cigarettes for smokers, they are not completely safe and should be avoided by nonsmokers and those with health conditions. Smoking both e-cigarettes and cigarettes can expose users to high nicotine levels and health risks. Switching to e-cigarettes may reduce smoking costs and risks of tobacco-related diseases while still providing a nicotine source. Users should carefully choose e-cigarette brands and monitor their nicotine intake when switching.