Cannabis use among adults who smoke tobacco: Relations with switching from combusted cigarettes to e-cigarettes or very low nicotine cigarettes

Introduction

Evidence is mixed regarding whether cannabis use impairs tobacco smoking cessation. This study tests the hypothesis that people who co-use tobacco and cannabis are less likely to switch to an alternative tobacco product when asked to do so.

Study design

Secondary data analysis of a mixed design with a within-subjects factor (active nicotine patch vs. placebo patch) and a between-subjects factor (study product). Participants sampled their assigned study product for 1 week, then were asked not to smoke their usual brand cigarettes and use only their study product and the study patches for 1 week (a switch week). A washout week was followed by a second switch week during which participants used the other patch type.

Setting/participants

Research office. Adults not motivated to quit smoking who smoke ≥ 5 cigarettes/day.

Intervention

Study products (very low nicotine cigarettes [VLNCs], e-cigarettes or no product) were provided for 4 weeks and 1 week of active nicotine patches and 1 week of placebo patches were provided in double-blind and counterbalanced fashion, for the switch weeks.

Main outcome measures

Number of usual brand cigarettes smoked during the switch weeks.

Results

Data collected September 2019-June 2022 and analyzed November-December 2024. Participants who reported past 30-day co-use of cannabis at baseline (n = 56) smoked significantly more usual brand cigarettes during switch weeks than those who did not co-use (n = 104; p = .03) and were less likely to make a tobacco cessation attempt (p < .05).

Conclusions

Cannabis use is associated with less switching from cigarettes to VLNCs or e-cigarettes.

Trial registration

Clinicaltrials.gov (NCT04084210).