The National Academies of Sciences, Engineering, and Medicine (NASEM) released a consensus report on the public health consequences of e-cigarettes in January 2018. The report reviews the health effects of e-cigarettes, which are battery-powered devices that deliver nicotine-containing aerosols. E-cigarettes have become popular, with millions of adults and youth using them. The FDA extended its regulatory authority to e-cigarettes in 2016, prompting a review of their health impacts. The NASEM Committee found conclusive evidence that e-cigarettes contain and emit numerous potentially toxic substances, though the number and levels vary by product and usage. Exposure to these substances is generally lower than in combustible cigarettes. Nicotine intake from e-cigarettes is highly variable. While there is no conclusive evidence of long-term health effects, intermediate endpoints suggest biological effects, such as increased heart rate and respiratory symptoms in adolescents. Substantial evidence shows that e-cigarette users are more likely to try combustible cigarettes. The effectiveness of e-cigarettes as smoking cessation aids is limited, but nicotine-containing e-cigarettes are more effective than those without nicotine. E-cigarettes may reduce exposure to toxicants and carcinogens compared to combustible cigarettes, potentially offering public health benefits over the next 30 years. Research needs include addressing knowledge gaps and improving study methods. Recommendations include cohort studies and randomized controlled trials. Limitations include the short time e-cigarettes have been in use and variability in device characteristics. The report highlights public health concerns about youth use, with evidence that e-cigarette use increases the likelihood of future smoking. Physicians should consider integrating questions about nicotine use in pediatric care and counsel patients on quitting. E-cigarettes are less harmful than combustible cigarettes but not without biological effects. Physicians should prioritize FDA-approved smoking cessation medications and consider e-cigarettes only if other options fail. The NASEM report is the most comprehensive review of e-cigarette health effects. While long-term effects are unclear, e-cigarettes pose less risk than combustible cigarettes. More research is needed to improve understanding and methods.The National Academies of Sciences, Engineering, and Medicine (NASEM) released a consensus report on the public health consequences of e-cigarettes in January 2018. The report reviews the health effects of e-cigarettes, which are battery-powered devices that deliver nicotine-containing aerosols. E-cigarettes have become popular, with millions of adults and youth using them. The FDA extended its regulatory authority to e-cigarettes in 2016, prompting a review of their health impacts. The NASEM Committee found conclusive evidence that e-cigarettes contain and emit numerous potentially toxic substances, though the number and levels vary by product and usage. Exposure to these substances is generally lower than in combustible cigarettes. Nicotine intake from e-cigarettes is highly variable. While there is no conclusive evidence of long-term health effects, intermediate endpoints suggest biological effects, such as increased heart rate and respiratory symptoms in adolescents. Substantial evidence shows that e-cigarette users are more likely to try combustible cigarettes. The effectiveness of e-cigarettes as smoking cessation aids is limited, but nicotine-containing e-cigarettes are more effective than those without nicotine. E-cigarettes may reduce exposure to toxicants and carcinogens compared to combustible cigarettes, potentially offering public health benefits over the next 30 years. Research needs include addressing knowledge gaps and improving study methods. Recommendations include cohort studies and randomized controlled trials. Limitations include the short time e-cigarettes have been in use and variability in device characteristics. The report highlights public health concerns about youth use, with evidence that e-cigarette use increases the likelihood of future smoking. Physicians should consider integrating questions about nicotine use in pediatric care and counsel patients on quitting. E-cigarettes are less harmful than combustible cigarettes but not without biological effects. Physicians should prioritize FDA-approved smoking cessation medications and consider e-cigarettes only if other options fail. The NASEM report is the most comprehensive review of e-cigarette health effects. While long-term effects are unclear, e-cigarettes pose less risk than combustible cigarettes. More research is needed to improve understanding and methods.