Vaping devices, introduced to the US market in 2007 as aids for smoking cessation, have become popular among youth and young adults because of their enticing fl avors and perceived lack of negative health effects. However, evidence is emerging that vaping may introduce high levels of dangerous chemicals into the body and cause severe lung injury and death. This article reviews the history and prevalence of vaping and available research on its health effects and effi cacy in smoking cessation, and proposes recommendations for clinicians and legislators to reduce harms associated with vaping. KEY POINTS Vaping is a common gateway to tobacco and marijuana use for adolescents and adults. The Juul vaping device delivers high nicotine concentrations that may pose a higher risk of nicotine addiction. Vaping has had unintended consequences that include poisoning of children who swallowed liquid nicotine, fi res and explosions from defective batteries in the devices, and effects on the developing brain. Vaping is associated with respiratory illness and, in rare cases, death, likely due to vaporized agents introduced into the lungs. Small amounts of heavy metals, acetone, and other carcinogenic compounds in the vaping aerosol may cause lung damage.