An electronic cigarette or e-cigarette is a handheld electronic device that vaporizes a flavored liquid. The user inhales the vapor. Using e-cigarettes is often called vaping. The fluid in the e-cigarette, called e-liquid, is usually made of nicotine, propylene glycol, glycerine, and flavorings.
The health risks of e-cigarettes are uncertain. While they are likely safer than tobacco cigarettes, the long-term health effects are not known. There is early evidence they can help people quit smoking although they have not been proven to work better than safer, regulated nicotine replacement products. Their value in tobacco harm reduction is unclear, but they could help to lower tobacco-related death and disease if examined more thoroughly. No serious adverse effects have been reported in trials. Less serious adverse effects include throat and mouth irritation, vomiting, nausea, and coughing. Non-smokers who use nicotine-containing e-liquids risk addiction to nicotine.
E-cigarettes create an aerosol, commonly called vapor, of flavors, glycerol and propylene glycol. Its composition varies across and within manufacturers. The vapor can contain toxicants and traces of heavy metals at levels permissible in inhalation medicines, and some potentially harmful chemicals not found in tobacco smoke at concentrations permissible by workplace safety standards. However, chemical concentrations may exceed the stricter public safety limits. High aldehyde levels, which have been generated in laboratory settings by overheating e-liquid, cause a strong bitter taste.
The modern e-cigarette was first invented in 2003 by Chinese pharmacist Hon Lik, and as of 2015 most e-cigarettes are made in China. Since they were brought to the market in 2004 their global use has risen exponentially. In the UK users have increased from 700,000 in 2012 to 2.6 million in 2015. In the United States e-cigarettes are used by a significant portion of young people and adults. Reasons for using e-cigarettes involve trying to quit smoking, though many use them recreationally. A majority still smoke tobacco, causing concerns that dual use may "delay or deter quitting". About 60% of UK users are smokers and roughly 40% are ex-smokers, while use among never-smokers is "negligible". Because of overlap with tobacco laws and medical drug policies, e-cigarette legislation is debated in many countries. The European Parliament passed regulations which came into effect in 2016, standardizing liquids and vaporizers, listing ingredients, as well as child-proofing liquid containers. As of August 2016, the US FDA extended its regulatory power to include e-cigarettes. As of 2014, there were 466 brands of e-cigarettes with global sales of around $7 billion.