1 INTREPID Lab, Addictions Program, Centre for Addiction and Mental Health, Toronto, ON, Canada.
2 INTREPID Lab, Addictions Program, Centre for Addiction and Mental Health, Toronto, ON, Canada; Institute for Mental Health Policy Research, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.
3 Department of Health, Kinesiology, and Applied Physiology, Concordia University, Montreal, QC, Canada; Montreal Behavioural Medicine Centre, Centre intégré universitaire de santé et de services sociaux du Nord-de-l'Île-de-Montréal (CIUSSS-NIM), Montreal, QC, Canada.
4 Division of Adolescent Medicine, Department of Pediatrics, Sainte-Justine University Hospital Centre, Montreal, QC, Canada; Department of Pediatrics, University of Montreal, Montreal, QC, Canada.
5 Department of Oncology, McMaster University, Hamilton, ON, Canada; Ontario Health (Cancer Care Ontario), Clinical Lead, Smoking Cessation, Primary and Community-based Care, ON, Canada.
6 Addictions Department, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
7 INTREPID Lab, Addictions Program, Centre for Addiction and Mental Health, Toronto, ON, Canada; Institute for Mental Health Policy Research, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada; Department of Family and Community Medicine, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
8 Division of Respiratory Medicine, Department of Pediatrics, SickKids & University of Toronto, Toronto, ON, Canada.
9 INTREPID Lab, Addictions Program, Centre for Addiction and Mental Health, Toronto, ON, Canada; Department of Family and Community Medicine, University of Toronto, Toronto, ON, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
10 Institute for Mental Health Policy Research, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
11 Department of Behavioural Science and Health, Institute of Population Health, University College London, London, UK.
12 Department of Thoracic Medicine, Royal Adelaide Hospital, South Australia, Australia; School of Medicine, University of Adelaide, South Australia, Australia.
13 INTREPID Lab, Addictions Program, Centre for Addiction and Mental Health, Toronto, ON, Canada; Institute for Mental Health Policy Research, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; Department of Psychiatry, University of Toronto, Toronto, ON, Canada. Electronic address: peter.selby@camh.ca.

Objective: To develop evidence-informed recommendations on the health effects of e-cigarettes to guide healthcare practitioners and the public to balance individual and population harm reduction.

Methods: Systematic and umbrella reviews investigating the health effects of e-cigarette use were conducted (September 2017 - January 2024). An international panel of subject matter experts (n = 23) and people in Canada with lived experience (n = 7) participated in a two-day, hybrid meeting, and used a consensus-based approach to develop recommendations. A guidance resource and four accompanying knowledge products were tested for usability with end users.

Results: Consensus was reached on 14 recommendations spanning four health effects: carcinogen exposure, cardiovascular health, respiratory health, and nicotine dependence. Quality of evidence was voted as ranging from high/moderate to moderate/low, and strength of most recommendations was voted as strong.

Conclusions: Guidance has been informed by best available evidence and expertise, providing direction to support decision-making. The use of established methods to evaluate divergent published literature combined with consensus-building methods among a range of stakeholders on vaping is possible. As higher quality evidence continues to emerge, recommendations will require iterative refinement.