Associations Between Cannabis Use, Sexual Behavior, and Sexually Transmitted Infections/Human Immunodeficiency Virus in a Cohort of Young Men Who Have Sex With Men.

Among men who have sex with men (MSM) the relationship between sexually transmitted infections (STIs) and cannabis use is not well established. We assessed cannabis use, sexual behavior, and STIs including human immunodeficiency virus (HIV) in a diverse cohort of young MSM.In Los Angeles, the mSTUDY cohort conducted visits every 6 months with 512 MSM between 2014 and 2017 collecting demographics, sexual behaviors, and reports of frequency of substance use. Each visit conducted testing for gonorrhea, chlamydia, and syphilis via blood, urine, and pharyngeal and rectal swabs by PCR, Human immunodeficiency virus was assessed using rapid tests for HIV-negatives and viral load for HIV-positives. We analyzed the relationship between cannabis use, sexual behaviors and STIs/HIV across 1535 visits.Significantly fewer participants tested positive for STIs at visits when reporting the previous 6 months use of only cannabis (11.7%) compared with no drugs (16.3%) or other drugs (20.0%, P = 0.01). Fewer MSM reporting only cannabis use than no or other drug use had been incarcerated, had incarcerated partners, experienced interpersonal violence, and were HIV-positive. In multivariable analyses visits with positive STIs were associated with other drug use (adjusted odds ratio, 1.69; 95% confidence interval, 1.03-2.78) but not use of cannabis only or no drug use after controlling for age, HIV status, new sex partners, and number of sex partners.When MSM reported using cannabis exclusively fewer STIs were detected and lower risk sexual engagements reported than when MSM reported no drug or other drug use.