Background:
Debate continues about whether electronic cigarettes (e-cigarette) and heated tobacco products (HTP) reduce or increase the probability of smoking, with many studies compromised by stated or unstated conflicts of interest.

Objective:
Taking advantage of a large prospective Italian cohort study, we evaluated the impact of novel (tobacco) products on conventional smoking behavior.

Methods:
A total of 3185 participants in a representative sample of the general Italian population aged 18–74 years provided baseline (April–May) and follow-up (November–December) responses in 2020, reporting smoking status and use of e-cigarettes and heated tobacco products (HTP). We tracked transitions over that period and report odds ratios (OR) and corresponding 95% confidence intervals (CI) for changes in smoking in relation to baseline use of e-cigarettes and HTPs.

Results:
Never cigarette smokers who used e-cigarettes at baseline were much more likely to start smoking compared with never users (OR=10.98; 95% CI: 6.62–18.23) and current HTP users (OR=6.92; 95% CI: 3.96–12.09). The 17.2% of ex-smokers who relapsed at follow-up were more likely to be e-cigarette users (OR=7.05; 95% CI: 3.30–15.05) and HTP users (OR=9.78; 95% CI: 3.62–26.49). Among current smokers at baseline, those who had quit smoking at follow-up were 14.6% overall, but only 6.7% among current e-cigarette users and none among current HTP users.

Conclusions:
Both e-cigarette and HTP use predict starting smoking and relapse and did not increase – and may even have reduced – smoking cessation among current smokers. These findings do not support the use of e-cigarettes and HTPs in tobacco control, at least in Italy, and reinforce the importance of regulating novel (tobacco) products the same way as conventional cigarettes.