E-cigarettes are electronic devices that are “smoked” or “vaped” like regular cigarettes. There are different kinds of e-cigarettes, including “1st generation” disposables and two piece e-cigarettes (ciga-likes) and “2nd generation” personal vaporizers (tank systems) and mods.
First Generation e-Cigarettes
Second Generation e-Cigarettes
When someone puffs on an e-cigarette, a sensor detects the puff and sends a signal to the battery. The battery turns on a mini-heater which heats the liquid nicotine. This creates a vapor which is inhaled and then exhaled. The exhaled vapor looks similar to tobacco smoke. Some of the nicotine in e-cigarettes is absorbed through the lining of the mouth and throat—not as much in the lungs, unlike regular cigarettes.1
E-cigarettes use small cartridges or refillable tanks of liquid. This liquid, or “e-juice”, is often made of nicotine, flavoring, and other chemicals like propylene glycol and vegetable glycerin. Although e-cigarettes don’t contain tobacco, most of them do contain nicotine. Most cartridges and tanks can be refilled or changed, depending on the type of e-cigarette.2
Studies with healthy individuals who have short-term exposure reveal little or no evidence of severe adverse events.3 More studies are recommended. Research on efficacy of e-cigarettes for smoking cessation is scant. While self-report and anecdotal evidence suggests that e-cigarettes can help people quit smoking, there is not enough empirical evidence at present to conclude that e-cigarettes are an effective quitting aid. They are not currently approved by the U.S. FDA or included in the U.S. Public Health Services Clinical Practice Guideline for treating tobacco use and dependence.
 Bullen C., McRobbie H., Thornley S. et al. Effect of an electronic nicotine delivery device (e cigarette) on desire to smoke and withdrawal, user preferences and nicotine delivery: randomised cross-over trial. Tobacco Control 2010; 19:98–103.
 Legacy Health (2013). Tobacco Fact Sheet: Electronic Cigarettes (E-cigarettes). Retrieved September 25, 2014, from: http://www.legacyforhealth.org/content/download/582/6926/file/insider.helpline.net
 Aruni Bhatnagar et al. Electronic Cigarettes: A Policy Statement from the American Heart Association. Circulation: Journal of the American Heart Association, August 24, 2014. Print ISSN: 0009-7322. Online ISSN: 1524-453.