This report aims to provide a systematic overview of the contemporary evidence on the health effects of nicotine and non-nicotine e-cigarette use, excluding where possible use of tetrahydrocannabinol (THC) and other illicit substances. The primary health outcomes of interest include, but are not limited to: dependence; cardiovascular disease; cancer; respiratory disease; oral diseases; reproductive outcomes; injuries and poisonings; mental health conditions; and environmental hazards with human health implications. These findings are integrated with those from previous systematic reviews on smoking uptake and cessation.