Immediate Switching to Reduced Nicotine Cigarettes in a U.S.-Based Sample: The Impact on Cannabis Use and Related Variables at 20 Weeks.

This article focuses on a secondary analysis of a multisite randomized clinical trial examining the effects of switching to very low nicotine content cigarettes (VLNC; 0.4 mg/g nicotine) on smoking behavior and toxicant exposure among adults who co-use cigarettes and cannabis versus those who smoke cigarettes only. Over 20 weeks, both groups assigned to VLNC cigarettes showed similar reductions in cigarettes per day (CPD), nicotine exposure (total nicotine equivalents, TNE), and tobacco-specific carcinogen exposure (NNAL). However, the cigarette-only group experienced greater reductions in non-tobacco-specific toxicants and carcinogens, such as carbon monoxide (CO), 2-cyanoethylmercapturic acid (CEMA), and phenanthrene tetraol (PheT), compared to the co-use group, likely due to continued exposure from combustible cannabis use. Additionally, those who co-use and switched to VLNC cigarettes exhibited a slight but statistically significant increase in cannabis use over time, averaging about two additional days of use per year, though the clinical significance of this increase remains uncertain.