The rising occurrence of vaping nicotine and cannabis among young adults has generated concerns regarding the potential health risks and addictive behaviors associated with simultaneous use. Previous research indicates that the co-use of these substances may enhance overall consumption and increase dependence; however, data on the specific patterns of co-vaping that contribute to elevated substance use remains limited. To address the identified gaps, this study aims to compare differences in the intensities of vaping nicotine and cannabis across four day-level patterns of vaping within 30 days: (1) non-vaping, (2) single substance vaping (vaping either nicotine or cannabis, or same-month co- vaping), (3) same-day different-occasion co-vaping (vaping both nicotine and cannabis on the same day but on different occasions), and (3) same- occasion co-vaping (vaping both nicotine and cannabis on the same occasion on a given day).
The study recruited 111 participants, aged 18–29, who reside in California and have vaped nicotine or cannabis on at least 20 days in the previous month, with a stated intention to quit vaping within the next six months. Data were collected over a 30-day period using a smartphone app via a daily diary method. A baseline Qualtrics survey gathered information on demographics, substance use history, vaping behaviors, mental health status, and perceived harm; subsequently, participants reported the number of times they vaped nicotine and cannabis, along with related details, between 9 PM and midnight each day. Generalized linear mixed-effects models were employed to examine the relationships between vaping patterns and vaping intensity, while controlling for covariates including demographic factors, substance dependence, and mental health conditions.
The findings of the study indicate that 84.7% of participants engaged in co-vaping both nicotine and cannabis over the past 30 days. Daily assessments showed that vaping nicotine exclusively was the most common pattern (42.7% of daily reports), while cannabis-only vaping was less frequent (9.7%). Co-vaping on the same day but during different occasions was reported by 16.5% of participants, and co-vaping during the same occasion was noted by 16.9%. Multilevel mixed-effects linear regression analyses revealed that closer temporal proximity in co-vaping was related to higher vaping intensity for both substances. In comparison to days without vaping, co-vaping on the same occasion was associated with the most significant increase in vaping intensity, with nicotine and cannabis vaping intensities being 11.34 and 6.86 times higher, respectively. Furthermore, engaging in co-vaping on the same day but on different occasions also resulted in greater vaping intensity compared to single-substance vaping, although to a lesser degree than that observed with same-occasion co-vaping.
Factors such as alcohol consumption, e-cigarette dependence, and cannabis use disorder were found to be positively correlated with both the intensity and frequency of vaping, a trend consistently supported by sensitivity analyses. These results suggest that co-vaping, particularly within the same occasion, may lead to increased consumption of both nicotine and cannabis, thereby underscoring the importance of tailored interventions for this pattern.
Takeaway: Co-vaping nicotine and cannabis on the same occasion significantly increases vaping intensity, highlighting the need for targeted interventions.