Marijuana-alcohol combo more risky in many ways, finds new study

With both marijuana and alcohol being legal in the US, researchers have found that an increasing proportion of people are using both drugs in combination. However, this is a risky thing to do, says a new study. The increased risk is largely due to the overlap of effects between the two separate drugs.

The current research focused on finding out what factors promoted the simultaneous use of alcohol and marijuana, compared to the use of alcohol alone. It also looked at the outcomes of combined use, and the association of this combination with frequency of use of either drug.

Image Credit: OSTILL is Franck Camhi / Shutterstock
Image Credit: OSTILL is Franck Camhi / Shutterstock

The results are frightening. They show that people who use alcohol in conjunction with marijuana have much higher chances of drinking more liquor and using more marijuana more frequently in higher amounts. Not only so, the rate of alcohol-related behavioral and other issues was much higher in this group.

These findings, published in the Journal Substance Use & Misuse, indicate the need to consider the role of substances like marijuana when setting up programs to prevent and stop alcoholism, since these additional drugs plainly alter the course of the drinking episode when taken together.

Researcher Ashley Linden-Carmichael says, “The results suggest that individuals who simultaneously use alcohol and marijuana are at a disproportionately higher risk for heavy, frequent, and problematic substance use.” She added that while prevention and intervention programs ask about whether students drink, they don’t always ask whether students are on other drugs, and especially if they are using other drugs simultaneously with alcohol. This is an omission which must be corrected since the combination of drugs is typically a high-risk situation. Thus this risk must be communicated properly to students.

The study found that in the US, more young adults than ever before are using marijuana which could enhance the chances that marijuana and alcohol are being used together. The risks to the users include impaired thinking, judgment, perception and motor activity. Hence the current emphasis of research in this area is to find the reasons why these two substances are being used together and what the effects of this combination look like.

The researchers in the current study looked into different situations which lead to the simultaneous use of alcohol and marijuana, trying to find out what kind of people were more likely to do this. For instance, they tried to find if people who chose to use both drugs together had traits like constantly searching for novelty and excitement, or wanting to experience sensational things.

To do this, they asked over 1000 people from 49 US states, aged between 18 and 25 years, to tell them how often they used either alcohol or marijuana, or both together. The participants also completed questionnaires that asked about issues that arose from their drinking, about their tendency to seek sensation, and their perceptions about how their close friends drank as a matter of habit, all within the last year. Almost 70% of the participants were male, Caucasian in origin, and had been educated for some time at college.

The results were analyzed, and showed that in all cases and in all situations, people were at greater risk of untoward sequelae when they used marijuana at the same time as they drank alcohol, compared to those who only drank. This was even after compensating for other confounding factors such as the number of drinks that the individual usually drank.

Some of these sequelae included falling unconscious, getting into arguments, and other behaviors which were usually regretted by the participant later. In addition, says Linden-Carmichael, “70 percent of those who engaged in simultaneous use reported using at least weekly.”

In short, the use of marijuana and alcohol simultaneously causes more frequent and heavy drinking, over a longer period, as well as increased and more frequent marijuana use. This was found to be associated with a personality with sensation-seeking traits, and with the individual’s perception that their friends were drinking more alcohol.

The report concludes: “It is clear that SAM users are a vulnerable sub-population of young adult drinkers. SAM users are differentiated from alcohol-only users in terms of their personality characteristics and perceptions of peer groups’ drinking. SAM users and more frequent users are also at heightened risk for substance use outcomes.”

Journal reference:

Ashley N. Linden-Carmichael, Amy L. Stamates & Cathy Lau-Barraco (2019) Simultaneous Use of Alcohol and Marijuana: Patterns and Individual Differences, Substance Use & Misuse, DOI: 10.1080/10826084.2019.1638407,

Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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