Marijuana use did not affect HIV prevention pill adherence among gay and bisexual men
Among 104 PrEP-using gay and bisexual men tracked over 10 weeks, marijuana use and heavy drinking did not affect daily PrEP adherence, while club drug use increased the odds of missing a dose by 55-60%.
Quick Facts
What This Study Found
No event-level effect of marijuana use or heavy drinking on PrEP adherence was found. Club drug use increased odds of missing PrEP by 55% same-day and 60% next-day. Missing one dose increased odds of missing the next day by eightfold. Club drug users averaged 1.6 missed doses in 30 days.
Key Numbers
104 participants, 9,532 days of data, 10 weeks. Club drugs: 55% increased odds same-day, 60% next-day (carryover effect). Missing one dose: 8x odds of missing the next day. Marijuana: no significant effect. Heavy drinking: no significant effect.
How They Did This
Retrospective 30-day timeline follow-back interviews plus prospective semi-weekly diaries for 10 weeks with 104 PrEP-using gay and bisexual men (half club drug users), generating 9,532 person-days of data.
Why This Research Matters
Concerns that cannabis might interfere with medication adherence are not supported here. For HIV prevention specifically, cannabis use does not appear to compromise the effectiveness of daily PrEP, while club drugs do present a genuine risk.
The Bigger Picture
This distinction between substance types matters for clinical counseling. Rather than warning PrEP users about all substance use broadly, clinicians can focus their attention on the specific substances that actually compromise adherence.
What This Study Doesn't Tell Us
Small sample (n=104). Self-reported substance use and PrEP adherence. All participants were from one city. Club drug use was the primary research focus, with marijuana as a secondary analysis.
Questions This Raises
- ?Would these findings hold in larger, more diverse samples?
- ?Does cannabis use affect adherence to other medications or just PrEP?
- ?Could the lack of marijuana effect reflect lower intoxication severity compared to club drugs?
Trust & Context
- Key Stat:
- Marijuana and heavy drinking: zero effect on PrEP adherence across 9,532 person-days
- Evidence Grade:
- Moderate: prospective daily diary data with detailed substance tracking, though small sample.
- Study Age:
- Published in 2019.
- Original Title:
- Determining the Roles that Club Drugs, Marijuana, and Heavy Drinking Play in PrEP Medication Adherence Among Gay and Bisexual Men: Implications for Treatment and Research.
- Published In:
- AIDS and behavior, 23(5), 1277-1286 (2019)
- Authors:
- Grov, Christian, Rendina, H Jonathon(2), John, Steven A, Parsons, Jeffrey T
- Database ID:
- RTHC-02054
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Does marijuana make you forget to take medications?
Not according to this study. Marijuana use showed no significant effect on daily PrEP adherence across nearly 10,000 person-days of data. Club drugs (cocaine, ecstasy, ketamine) did increase missed doses by 55-60%.
Why did missing one dose matter so much?
Missing one PrEP dose increased odds of missing the next day by 8x, creating a cascading effect. This pattern was driven by club drug use events, not marijuana, suggesting club drugs create multi-day disruptions to routine.
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Cite This Study
https://rethinkthc.com/research/RTHC-02054APA
Grov, Christian; Rendina, H Jonathon; John, Steven A; Parsons, Jeffrey T. (2019). Determining the Roles that Club Drugs, Marijuana, and Heavy Drinking Play in PrEP Medication Adherence Among Gay and Bisexual Men: Implications for Treatment and Research.. AIDS and behavior, 23(5), 1277-1286. https://doi.org/10.1007/s10461-018-2309-9
MLA
Grov, Christian, et al. "Determining the Roles that Club Drugs, Marijuana, and Heavy Drinking Play in PrEP Medication Adherence Among Gay and Bisexual Men: Implications for Treatment and Research.." AIDS and behavior, 2019. https://doi.org/10.1007/s10461-018-2309-9
RethinkTHC
RethinkTHC Research Database. "Determining the Roles that Club Drugs, Marijuana, and Heavy ..." RTHC-02054. Retrieved from https://rethinkthc.com/research/grov-2019-determining-the-roles-that
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.