Alcohol and Marijuana, Two Legal Drugs Especially Harmful When Used Together

Teenager woman feels sick

When teenagers and young adults use cannabis and alcohol simultaneously, their health risks become exponentially more dire than if they used cannabis one day and alcohol the next. To be clear, no form of drug use is safe or acceptable, but it seems using multiple drugs at once is significantly more dangerous for young people. Given that there is a rising trend of polysubstance abuse among all age demographics (using more than one drug at once), the following data is something health officials, policymakers, and the friends and family members of addicts should become familiar with.

Findings from the National Institute on Drug Abuse and Other Studies

Thanks to the findings of several recently published studies, there are some new and critical data points that parents, siblings, and other loved ones of young people who use drugs must understand:

  • College students who use marijuana and alcohol simultaneously experience more negative health consequences than students who use them separately.
  • Students who go back and forth between alcohol and cannabis report more unwanted health outcomes than those who use only alcohol or only cannabis.
  • Young people tend to drink more alcohol on the days they also use marijuana than on the days when they abstain from marijuana.
  • Young adults report more physical, mental, emotional, and psychological harm on days that they use both cannabis and alcohol than on days when they use only one substance.
  • Young people who consume cannabis and alcohol simultaneously are more likely to experience excessive alcohol consumption, vomiting, nausea, and hangovers.
  • Young people who consume cannabis alongside alcohol also report more negative cannabis-related effects, like memory loss, embarrassing moments, and other unwanted mental and behavioral outcomes.
  • People who use both drugs simultaneously are more likely to experience serious life-changing effects like DUIs, blackouts, and some loss of cognitive function.
  • Individuals who used cannabis and alcohol simultaneously (regardless of which drug they used more) reported more harm to their academic, occupational, and social lives. They also reported harm to their self-care.
  • Finally, people who use cannabis and alcohol simultaneously are more likely to develop a physical dependence on one or both substances and are more likely to engage in risky behaviors while under the influence of both substances.

Why Are Young People Using Both Drugs at Once?

Teenagers party

Scientists are still analyzing the physiological effects of people experimenting with alcohol and cannabis simultaneously. One paper determined that people who use cannabis feel compelled to drink more alcohol. In so doing, they also report more negative outcomes of that alcohol use. It could be that cannabis use enhances the effects of alcohol. However, that also means cannabis users are more likely to experience all of the negative effects of alcohol when they consume it but on a more severe level.

Another paper reported that people who consume cannabis and alcohol simultaneously are also more likely to experience binge drinking episodes and that these are often brought on by social interactions in which both alcohol and cannabis are being consumed. Using both drugs at once may compel users to consume more of each substance than they normally would.

Each of the four studies cited thus far also mentioned young people (particularly college students) using alcohol and cannabis in group settings, usually amongst peers. That usage pattern is quite different from other drug usage patterns, which are more likely to involve users abusing drugs alone. With that in mind, one might hypothesize that there is a peer pressure aspect to young people using cannabis and alcohol simultaneously.

Severe Risk to Young People and What Parents Must Do

Dad talks with son

When a young person is already using one drug and their body is already being negatively affected by that drug, adding a second drug into the mix is akin to throwing gasoline on a fire. There is no way of predicting how the second substance’s chemicals will interact with the first substance and how those chemical reactions will affect the user’s body. In many cases, like when stimulants (meth, cocaine) are mixed with opioids (heroin, fentanyl), addicts who use such mixtures often overdose and die as a result.

The Substance Abuse and Mental Health Services Administration reported in 2019 that about 60% of Americans 12 and older use at least one mind-altering substance at least once per month. This is a sharp uptick in overall usage rates. The effects of such usage trends are already apparent in rising overdose deaths. If polysubstance abuse is truly going to be the new drug trend in the coming years, it’s highly concerning to imagine what that future might look like. According to the Centers for Disease Control and Prevention, at least half of all drug-related fatalities involve a user using more than one type of drug at the time of death or in the hours or minutes leading up to death.

Looking to the future, the family members and loved ones of young people experimenting with “just” alcohol or “just” cannabis must take fast action to get their young loved ones help. There is no room for being permissive or accepting of “just” experimenting with one drug that may be legal and even perceived as harmless, not in a world where polysubstance abuse is becoming the leading (and fatal) drug trend.

If someone you know is using any mind-altering substance, ensure they seek help at a qualified drug and alcohol rehab center as soon as possible. Please don’t wait.


  • NIDA. “Using Alcohol and Marijuana Together Exacerbates Negative Consequences in Young Adults.” National Institute of Drug Abuse, 2021.
  • NIH. “Consequences of Alcohol and Marijuana Use among College Students: Prevalence Rates and Attributions to Substance-Specific versus Simultaneous Use.” National Institutes of Health, 2020.
  • NIH. “A daily study comparing alcohol-related positive and negative consequences for days with only alcohol use versus days with simultaneous alcohol and marijuana use in a community sample of young adults.” National Institutes of Health, 2020.
  • NIH. “Simultaneous Alcohol and Marijuana Use in Daily Life: Implications for Level of Use, Subjective Intoxication, and Positive and Negative Consequences.” National Institutes of Health, 2020.
  • SAMHSA. “Key Substance Use and Mental Health Indicators in the United States: Results from the 2019 National Survey on Drug Use and Health.” Substance Abuse and Mental Health Services Administration, 2019.
  • CDC. “Polysubstance Use Facts.” Centers for Disease Control and Prevention, 2022.



After working in addiction treatment for several years, Ren now travels the country, studying drug trends and writing about addiction in our society. Ren is focused on using his skill as an author and counselor to promote recovery and effective solutions to the drug crisis. Connect with Ren on LinkedIn.