Background: Most smokers attempting to quit relapse. There is little evidence whether the use of e-cigarettes (‘vaping’) increases or decreases relapse. This study aimed to assess 1) whether vaping predicted relapse among ex-smokers, and 2) among ex-smokers who vaped, whether vaping characteristics predicted relapse.

Methods: Longitudinal web-based survey of smokers, recent ex-smokers and vapers in the UK, baseline in May/June 2016 (n = 3334), follow-up in September 2017 (n = 1720). Those abstinent from smoking ≥ 2 months at baseline and followed up were included. Aim 1: Relapse during follow-up was regressed onto baseline vaping status, age, gender, income, nicotine replacement therapy use and time quit smoking (n = 374). Aim 2: Relapse was regressed onto baseline vaping frequency, device type, nicotine strength and time quit smoking (n = 159).

Results: Overall, 39.6% relapsed. Compared with never use (35.9%), past/ever (45.9%; adjOR = 1.13; 95% CI, 0.61–2.07) and daily vaping (34.5%; adjOR = 0.61; 95% CI, 0.61–1.89) had similar odds of relapse, for non-daily vaping evidence of increased relapse was inconclusive (65.0%; adjOR = 2.45; 95% CI, 0.85–7.08). Among vapers, non-daily vaping was associated with higher relapse than daily vaping (adjOR = 3.88; 95% CI, 1.10–13.62). Compared with modular devices (18.9% relapse), tank models (45.6%; adjOR = 3.63; 95% CI, 1.33–9.95) were associated with increased relapse; evidence was unclear for disposable/cartridge refillable devices (41.9%; adjOR = 2.83; 95% CI, 0.90–8.95). Nicotine strength had no clear association with relapse.

Conclusion: Relapse to smoking is likely to be more common among ex-smokers vaping infrequently or using less advanced devices. Research into the effects of vaping on relapse needs to consider vaping characteristics.