Both e-cigarettes and cigarettes are more harmful, and while there is evidence that e-cigarettes are less harmful than traditional cigarettes and may help with quitting, there are still concerns that using e-cigarettes will cause quitters to relapse and that e-cigarettes use by teens may lead to smoking traditional cigarettes. It is better to quit both. Cigarettes contain tar and nicotine, which can enter the body through smoking and are very susceptible to lung cancer. E-cigarettes contain an atomizing device that heats up a special solution and produces a vapor for the user to inhale. The main components of the solution include nicotine and propylene glycol. These substances are also harmful to the human body, and excessive or prolonged inhalation can have certain effects on the body. Either way of smoking will cause damage to the human body. In addition to causing lung cancer, it is also prone to inducing cardiovascular and cerebrovascular diseases, as well as affecting other systems of the body, and people who smoke tend to have a higher risk of developing diseases such as esophageal and oral cancers than the general population as well. Therefore, both are more harmful, it is recommended to quit smoking as early as possible, do not take a chance and think that e-cigarettes are not very harmful.