In 2022, one out of five U.S. adults reported having used CBD in the preceding year, which is close to the 23 % rate of cannabis use. The study also shows the high prevalence of CBD-cannabis co-use, as almost two thirds of CBD users also used cannabis and more than one half of cannabis users also used CBD. With increasing cannabis legalization and use prevalence (Caulkins, 2024) and demand for CBD products (Grand View Research., 2024), co-use of CBD and cannabis is projected to grow rapidly.

Consistent with the findings of previous studies of young adults (e.g., Fedorova et al., 2021), multivariable findings show that CBD use, with or without cannabis use, was consistently higher among women but lower among Black and Hispanic individuals compared to non-Hispanic White individuals. The higher likelihood of CBD use among women may be because they are more likely to experience the kinds of health concerns and conditions (e.g., anxiety/depression, pain, and sleep problems) that CBD is often used for. Women also tend to use complementary and alternative medicine for chronic conditions more than do men (Alwhaibi and Sambamoorthi, 2016). The wellness industry, including CBD products, also often targets women more aggressively. Many CBD products are marketed for skincare, stress relief, and menstrual pain to appeal to women. The lower likelihood of CBD use among Blacks and Hispanics may be related to different cultural perceptions and attitudes towards cannabis and CBD among racial/ethnic groups. Access to CBD products can also vary significantly based on socioeconomic and geographic factors. CBD products can be expensive, and economic barriers may limit access for some racial/ethnic groups, especially among older adults with fixed income. Access to and use of CBD and other hemp-derived products versus THC products may also vary for those residing in states with or without medical and/or adult-use cannabis laws (Smart and Pacula, 2019).

As hypothesized, compared to non-users of CBD or cannabis, CBD-only users had more physical and mental health and substance use problems and lower cannabis risk perceptions. The significant associations between CBD-only use, compared to non-use of CBD or cannabis, and health problems show that despite largely uncertain medicinal effects of CBD (Kirkland et al., 2022, Revol et al., 2024), the users were likely attracted to perceived benefits or expectations of the benefits. As also hypothesized, the likelihood of CBD-only use, compared to cannabis-only use, was higher among older adults and those with higher SES and more chronic illnesses, but fewer substance use problems. As older adults had more physical health problems, it was expected that the likelihood of CBD-only use, compared to cannabis-only use, was significantly higher among older adults. However, CBD-only users and cannabis-only users did not differ on mental illness status, suggesting that mental illness is equally present in CBD-only and cannabis-only groups.

Some states approve use of medical cannabis, along with CBD, for some psychiatric problems (Scherma et al., 2020). Like CBD users, medical cannabis users perceived reduction in depression, anxiety, and stress (Cuttler et al., 2018). While these perceived mental health benefits may be significant reasons for people turning to cannabis and/or CBD use, nonmedical cannabis use was also found to impede recovery and mental healthcare use (Bahorik et al., 2018). Studies have also shown that compared to cannabis non-users, cannabis users and those with CUD have significantly higher odds of psychiatric and substance use disorders (Onaemo et al., 2021, Padwa et al., 2022) and that cannabis use, especially among youth and young adults, is a risk factor for mental disorders (Gobbi et al., 2019, Large et al., 2011, Urits et al., 2020). At the same time, CBD-only use versus cannabis-only use was also associated with higher cannabis risk perception. It appears that CBD-only users stayed away from cannabis use as they perceived THC use to be harmful but believed CBD to be therapeutic.

Compared to cannabis-only users, co-users of CBD and cannabis also had more mental as well as physical health problems. A study of young-adult cannabis and CBD users found that their CBD use was associated with health histories and motivations linked to pain and psychological problems (Fedorova et al., 2021). Our findings of age group not being a significant factor for co-use suggest that both young and older adult co-users shared similar motivations for using CBD. Our findings also show that the co-users are those at most risk in terms of potential harms of cannabis use, as they, compared to cannabis-only users, used cannabis at higher frequency, and were more likely to have moderate or severe CUD and illicit drug use problems. The co-users may also have believed that CBD could attenuate some of THC’s adverse effects (Moltke and Hindocha, 2021). However, previous controlled clinical laboratory studies and randomized clinical trials have shown that CBD can either attenuate or exacerbate the effects of THC by increasing the pharmacodynamics of THC (Arkell et al., 2019; Englund et al., 2013; Solowij et al., 2019; Zamarripa et al., 2023). While more research is needed to establish the safety and drug-drug interactions of CBD and cannabis co-use, the co-users with CUD and illicit drug use problems need help.

In the absence of research on drug-drug interactions and other safety controls, including pesticides and heavy metals (Gardener et al., 2022), the high rate of CBD use among those with physical and mental health problems is concerning as they are more likely to be on other medications. Research has shown that CBD has intrinsic pharmacologic effects and associated adverse drug events along with the potential for pharmacokinetic and pharmacodynamic drug-drug interactions (Balachandran et al., 2021; Brown & Winterstein, 2019). Again, more research is needed to examine how CBD affects the pharmacodynamics and pharmacokinetics of other substances, including psychotropic medications, cannabis, nicotine, alcohol, opioids, and illicit drugs, and its potential as a substitute for other substances.

The study has some limitations due to the NSDUH data constraints. First, the lack of data on types of CBD products and use reasons, frequency and dosage limited the study scope. Second, the NSDUH did not distinguish CBD from other hemp-derived products containing Δ⁸- or Δ¹⁰-THC that are widely available in the market (Geci et al., 2023). Public interest in Δ⁸-THC has been surging in recent years especially in states where Δ⁹-THC is restricted (Leas et al., 2022). Because cannabis plants contain only trace amounts of Δ⁸- or Δ¹⁰-THC, they are usually made synthetically from CBD and added to edible and inhaled products that are marketed as legal hemp products (Huang et al., 2024, Kaczor et al., 2024, Babalonis et al., 2021;). Third, given the low degree of consumer knowledge of THC and CBD levels (Hammond & Goodman, 2022), the reliability and validity of CBD use report is also a suspect. Fourth, since NSDUH is based on self-report data, the validity of respondents’ self-reported CBD, cannabis, and other substance use may have been affected by social desirability bias. Fifth, geographic differences in access to and use of CBD or hemp-derived and THC products were not captured.

Despite these limitations, the study findings expand the knowledge about CBD users by examining three groups—CBD-only users, cannabis-only users, and CBD-cannabis co-users—using the nationally representative U.S. adult sample. Implications of the findings are: First, more epidemiologic research is needed to examine demographic differences in CBD use patterns and reasons especially with increasing legalization and normalization of hemp-based and THC products. Second, special research and clinical attention needs to be paid to co-users of CBD and cannabis to discern potential benefits and negative effects of co-use. Third, those who used CBD for their mental health problems need to be provided information on the importance of seeking professional advice for mental health issues. Fourth, the high prevalence of self-reported CBD use especially among those with physical and mental health problems warrants public health warnings about potential side effects and drug interactions, especially with long-term use. Fifth, more effective laws and regulations are needed to ensure safety of hemp and THC consumer products. The existing laws are often confusing. For example, under the Federal Food, Drug, and Cosmetics Act, the FDA prohibits the addition of CBD, Δ⁸-, or Δ¹⁰-THC to food or beverage; however, CBD-containing dietary supplements are marketed using the structure/function claims (Li et al., 2021, Mead, 2019). The FDA acknowledged that the existing regulatory framework for foods and supplements are not appropriate for CBD (U.S. FDA, 2023). Policy development and reforms also need to be based on strong economic and social justice goals and in ways to protect science and public health from corporate influence (Sevigny et al., 2023; Shover & Humphreys, 2019).