Vaping as a gateway to smoking – evidence briefing

Key findings

The systematic reviews and meta-analyses on the gateway effect examined for this briefing have consistently found an association between vaping and subsequent smoking. However, the quality of the available evidence has often been questioned due to its heterogeneity (e.g. study design, terminology, different types of vaping devices on the market at the time of the research) and robustness (e.g. small sample size, self-reported measures, inadequate adjustment for potential confounders).

The examined sources show that:

• Despite the above-mentioned limitations, there is agreement in five out of eight reviews that vaping may act as a gateway to smoking (with the most recent review establishing 3 times higher odds of initiating tobacco cigarette smoking for vapers). This assessment is based on the consistency of results across studies.
• Three reviews out of eight conclude that, although there is a strong association between vaping and subsequent smoking, it is impossible to establish causality and determine whether the relationship is due to a gateway effect. Two of these reviews also suggest that the association may be due to the common liability hypothesis (i.e. the same genetic or environmental factors that increase the likelihood of someone vaping also increase the likelihood of someone smoking).

All the reviews highlight the need for more research, given studies’ limitations and the ever-evolving nature of vaping products. New primary studies underway and a systematic review by Cochrane due to be published in 2024 will add to our current knowledge of the gateway effect.