E-Cigarettes: The Science Behind the Smoke and Mirrors.

E-cigarettes are a diverse set of devices that are designed for pulmonary delivery of nicotine through an aerosol, usually consisting of propylene glycol, nicotine, and flavorings. The devices heat the nicotine solution using a battery-powered circuit and deliver the resulting vapor into the proximal airways and lung. Although the current devices on the market appear to be safer than smoking combusted tobacco, they have their own inherent risks, which remain poorly characterized due to widespread product variability. Despite rising use throughout the United States, predominantly by smokers, limited evidence exists for their efficacy in smoking cessation. Pending regulation by the FDA will enforce limited disclosures on the industry but will not directly impact safety or efficacy. Meanwhile, respiratory health practitioners will need to tailor their discussions with patients, taking into account the broad range of existing effective smoking cessation techniques, including pharmaceutical nicotine replacement therapy.