This study provides novel information about tobacco and cannabis co-use prevalence, overall and by sociodemographic variables, among people with HIV. Compared to U.S. adults without HIV, U.S. adults with HIV reported higher levels of tobacco and cannabis co-use, with an estimated 178,775 U.S. adults with HIV engaged in co-use. The elevated levels of tobacco and cannabis co-use in individuals with HIV remained significant across multiple sensitivity analyses, adjusting for additional covariates. The higher prevalence of co-use may be driven by the use of tobacco and cannabis to relieve stress associated with a diagnosis of HIV or for self-medication, such as pain and symptom management [23, 38]. Alternatively, individuals with HIV may also use tobacco and cannabis recreationally, similar to the general population [23, 39]. Future research should examine the underlying reasons and contextual factors (e.g., who, where, and when) associated with tobacco and cannabis co-use. Such insights would help inform tailored prevention and cessation strategies, including educational programs and public awareness campaigns, targeted at individuals with HIV.

We also examined sociodemographic differences in tobacco and cannabis co-use patterns among people with HIV. This study found significant interaction effects between HIV status and race/ethnicity in relation to tobacco and cannabis co-use, suggesting that non-Hispanic Black adults with HIV may be at increased risk for co-use. We speculate that this increased risk may result from targeted tobacco and cannabis marketing toward non-Hispanic Black communities, a pattern observed in the general population [40–42]. Additionally, non-Hispanic Black adults with HIV may experience heightened levels of stress due to racial and ethnic discrimination, compounded by greater HIV-related stigma compared to non-Hispanic White adults with HIV [43–45]. These findings are concerning, as they may contribute to worsening HIV-related health disparities and tobacco- and cannabis-associated health risks in this population. Given that non-Hispanic Black adults are already disproportionately affected by HIV [24], there is an urgent need to investigate the underlying factors driving this elevated co-use risk and to develop tailored clinical interventions and educational programs to address it.

This study also found a significant interaction between HIV status and state-level medical cannabis legalization status, indicating that U.S. adults with HIV living in states with medical cannabis laws may be at higher risk for tobacco and cannabis co-use. This finding is expected given that high levels of co-use of tobacco and cannabis are reported among the general population residing in states with legalized medical cannabis [1, 26, 46]. However, a study by Pravosud et al. found that while tobacco and cannabis co-use increased between 2017 and 2021 among adults in the U.S., it was not significantly associated with state-level medical or recreational cannabis legalization [47]. Although medical cannabis is recognized for its potential benefits in managing HIV-related inflammation and symptoms [14, 48], the combined effects of tobacco and cannabis co-use remain uncertain and may pose additional health risks for people with HIV. Further research is needed to clarify these potential harms and to inform evidence-based harm reduction strategies.

Notably, state-level medical cannabis legalization status attenuated the magnitude of the effects of HIV diagnosis on the risk of tobacco and cannabis co-use. One speculation is that living in a state with medical cannabis law might be related to increased exclusive cannabis and reduced level of tobacco use (i.e., a substitution effect). For example, a study by Dave et al. (2023) used two U.S. national datasets and observed that adoption of recreational cannabis laws were associated with increased levels of cannabis use, but decreased levels of tobacco use among adults [49]. Another study by De and Sun (2025) used the 2021–2022 Behavioral Risk Factor Surveillance System and observed that recreational cannabis laws were associated with current cigarette use [50]. A systematic review by Farrelly et al. (2023) found that recreational cannabis laws were associated with increased levels of cannabis use, in general, and decreasing rates of cigarette smoking, suggesting a potential substitution effect [51]. Even though these studies were specifically focused on recreational cannabis laws, we speculate that this substitution effect might affect the attenuated risk ratio of tobacco and cannabis co-use when considering HIV status. Another previous study by Weinberger and colleagues found that medical cannabis legalization was associated with an increase in cigarette and cannabis co-use, but no change in cigarette-only use or cannabis-only use among the overall U.S. population [26]. However, medical cannabis legalization was associated with increased levels in cigarette-only use and cannabis-only use among those aged 50 years and older, suggesting that there might be complex interactions between living in states with cannabis-related laws and other factors such as sociodemographics. Future studies should examine the complex interplay between cannabis-related laws, HIV status, and other factors.

This study provides novel insights into the prevalence of tobacco and cannabis co-use among people with HIV, highlighting subgroup differences based on sociodemographic factors, with important public health and clinical implications. A key strength of this study is the use of a nationally representative U.S. sample, which enhances generalizability and enables population-level estimates. Further, the findings are robust, supported by multiple sensitivity analyses incorporating additional covariates. However, this study has several limitations. First, data were self-reported, which may introduce biases, including recall bias and social desirability bias, particularly regarding HIV status and cannabis use behaviors. Second, the NSDUH survey includes only U.S. civilian, non-institutionalized individuals, excluding populations with higher levels of substance use and HIV vulnerability, such as incarcerated individuals and those experiencing homelessness [52, 53]. Third, the NSDUH does not collect detailed data on the frequency and dosage of tobacco and cannabis use, including nicotine concentration, THC concentration, and reasons for cannabis use (e.g., medicinal versus recreational cannabis use), nor does it distinguish between concurrent, simultaneous, or sequential use of tobacco and cannabis [54]. Fourth, unmeasured confounders may influence the observed associations, such as state-level recreational cannabis legalization status and exposure to tobacco and cannabis marketing. Fifth, even though we combined several years of US national datasets, the sample size of adults with HIV who reported past-month tobacco and cannabis co-use was still small enough that we were unable to examine the potential range of product combinations related to tobacco and cannabis co-use by HIV status (e.g., cigarette use versus vaping nicotine, vaping cannabis versus sublingual cannabis use). Future studies should employ a larger-scale HIV-focused dataset and examine the various co-use patterns among people with HIV.

Sixth, the public use NSDUH data only indicated whether respondents were living in a state that had passed a law allowing the use of cannabis for medical reasons at the time of the interview and more specific information about these medical cannabis laws was not available. For example, some states only allow low-THC products while others allow full cannabis use. Further, some states have restrictive laws that only permit CBD or require specific conditions (e.g., policy variation across states). Further, even though we used residence in a state with a medical cannabis law as a proxy for policy exposure, this measure may not capture individual-level awareness, eligibility, or access to medical cannabis programs, and such misclassification may affect observed effect modification. In addition, the residence in states with medical cannabis laws might not fully capture residence stability as respondents may move among states with different cannabis-related laws over time. Future studies should examine more detailed aspects of cannabis laws in relation to tobacco and cannabis co-use among people with HIV.