Do alcohol and marijuana use decrease the probability of condom use for college women?

Alcohol and marijuana use are thought to increase sexual risk taking, but event-level studies conflict in their findings and often depend on reports from a limited number of people or on a limited number of sexual events per person. With event-level data from 1,856 sexual intercourse events provided by 297 college women (M age = 18 years; 71% White), we used multilevel modeling to examine associations between alcohol and marijuana use and condom use as well as interactions involving sexual partner type and alcohol-sexual risk expectancies. Controlling for alternative contraception use, partner type, regular levels of substance use, impulsivity and sensation seeking, and demographics, women were no more or less likely to use condoms during events involving drinking or heavy episodic drinking than during those without drinking. However, for drinking events, there was a negative association between number of drinks consumed and condom use; in addition, women with stronger alcohol-sexual risk expectancies were marginally less likely to use condoms when drinking. Although there was no main effect of marijuana use on condom use, these data suggest marijuana use with established romantic partners may increase risk of unprotected sex. Intervention efforts should target expectancies and emphasize the dose-response relationship of drinks to condom use.