BACKGROUND: Alcohol and cannabis are commonly used together by young adults. With frequent pairings, use of one substance may become a conditioned cue for use of a second, commonly co-used substance. Although this has been examined for alcohol and cannabis in laboratory conditions and with remote monitoring, no research has examined whether pharmacologically induced cross-substance craving occurs in naturalistic conditions.

METHODS: In a sample of 63 frequent cannabis-using young adults (54% female) who completed 2 weeks of ecological momentary assessment, we tested whether alcohol use was associated with stronger in-the-moment cannabis craving. We also examined whether sex moderated this association and whether cannabis craving was stronger at higher levels of alcohol consumption.

RESULTS: Although alcohol use and cannabis craving were not significantly associated at the momentary level, there was evidence that this relation significantly differed by sex. Among female participants, there was a negative association between alcohol use since the last prompt and momentary cannabis craving (b = -0.33, SE = 0.14, p = 0.02), while the association among male participants was positive (b = 0.32, SE = 0.13, p = 0.01). Similarly, alcohol quantity was negatively associated with cannabis craving at the momentary level for female participants (b = -0.10, SE = 0.04, p = 0.009) but was not significantly associated for male participants (b = 0.05, SE = 0.04, p = 0.18).

CONCLUSIONS: Alcohol may enhance cannabis craving among male individuals but reduce desire for cannabis among female individuals. This may point to differing functions of co-use by sex, highlighting a need for research to elucidate the mechanisms underlying this increasingly common pattern of substance use.