New Research on Smoking Pot and Drinking at the Same Time

Photo: Burger/Phanie/Corbis

Lots of people drink and smoke pot at the same time. But according to researchers Meenakshi Subbaraman and William Kerr, there’s actually not much adult research into how frequently adults do so, or into whether combining the effects leads to worse stuff than using them separately. To change that, they decided to take a bunch of data from the self-reported 2005 and 2010 National Alcohol Surveys — 8,626 people, to be exact — and see which behaviors led to which outcomes. The results are published in a new paper in Alcoholism: Clinical and Experimental Research.

The data included basic demographics, information about how frequently, if ever, the respondents drank and smoked pot, and whether they indulged in both substance at the same time. It also measured whether their alcohol use had led to “social consequences” — defined as two or more of a list of 15 items pertaining to things like “work, fighting, and relationship problems” — and whether it had led to “harms” to family, work, and so on. 

Overall, the researchers found that simultaneous use of pot and alcohol was twice as prevalent as “concurrent” use, lending weight to the common-sense belief that many people enjoy combining the substances. Those who smoked and drank at the same time were 2.3 times more likely to have driven drunk, 3 times more likely to have dealt with social consequences as a result of their drinking, and more than twice as likely to have experienced the aforementioned “harms” as compared to those who only drank. But the researchers found less of an effect when comparing simultaneous users to concurrent users. There, the only significantly significant effect of combining was that simultaneous users reported being twice as likely to have driven drunk.

The researchers did control for demographic variables here, but overall the surveys weren’t designed in a way that allows for easy storytelling about what’s causing what. It could be that certain types of people are more likely to combine substances, for example, rather than that combining substances causes certain behaviors. But it certainly wouldn’t be shocking if smoking pot while drinking further reduced one’s inhibitions or decision-making capabilities, leading to non-smart behavior like driving under the influence.

Overall, though, there aren’t any loud alarm bells here: Yes, smoking and drinking at the same time isn’t ideal, and obviously both behaviors can be dangerous when indulged in irresponsibly, but this one study, at least, didn’t find anything dire. The researcher’s recommendations, in fact, are pretty reasonable: It might be a good idea, in states that have legalized pot, to require “distributors to include warning labels communicating risks (especially regarding driving) associated with combining alcohol and cannabis on all cannabis packaging.”

And, as always, more research is needed: “Clinicians could also consider asking substance use treatment clients to detail their co-use pattern as a way of identifying potential problems.” It certainly shouldn’t be hard to learn more about this, given the giant natural laboratories currently running in Washington State, Colorado, and elsewhere, with more surely to come.

Drinking and Smoking Pot: Not Great for You