Abstract The global rise of the number of smokers of electronic-cigarette (e-cigarette) who changed from conventional smoking of tobacco cigarettes in the last decade is a very interesting phenomenon which is connected with questionable benefits to human health. Electronic cigarettes (E‐cigarettes) are devices that can vaporize a nicotine solution combined with liquid flavours instead of burning tobacco leaves. The e-cigarettes were introduced in 2004 and became very quickly widely available, and their use has increased exponentially worldwide. The companies selling E‐cigarettes are aggressively advertise their products as beneficial to human health, helping people to follow smoking cessation. The e-cigarettes are conceived especially among young people as healthier than conventional tobacco smoking cigarettes, cheaper, and more socially acceptable. At first impression e-cigarette smoke is not harmful to the respiratory system, but on better inspection the vapour contains some harmful substances, suspented particulates and decomposition products. But the types or concentrations vary by brand, type of device, and how it is used. As a result, in the last 10 years there is some research on short-term health effects (in vitro, in vivo and observational studies) but studies on their long-term health risks are very limited. Research available has not shown that they are helpful for quitting smoking completely. Medical authorities are worrying that young people might get lured to start smoking e-cigarettes on the assumption that are harmless. This review contains some of the important studies and reports from medical authorities on the short- and long-term adverse health effects of e-cigarettes in the respiratory system in comparison with conventional tobacco smoke. Recently (August 2019), there was an announcement by the Centers for Disease Control and Prevention (CDC) and FDA that followed very closely pulmonary diseases connected with vaping of e-cigarette and other substances, such as cannabinoids products. CDC recorded 215 possible cases of severe pulmonary disease associated with the use of electronic cigarette that have been reported by 25 U.S. states and additional pulmonary illnesses are under investigation. Also, CDC announced hat at least 5 people have died from a mysterious lung disease linked to vaping (Illinois, Oregon, Indiana, etc), The CDC urges people in the USA to avoid vaping amid the outbreak of this misterious pulmonary disease. According to medical experts a possible explanation of developing lipoid pneumonia from vaping was that aerosolized oils deposited in their airways, causing local inflammation that impaired their lung function..