Study Shows Alcohol Boosts THC Levels in Your Blood

With 4 states legalizing recreational marijuana and several others considering the possibility, driving while high on pot is becoming a much bigger concern for motorists.

More Danger Behind the Wheel

Plenty of marijuana users routinely get behind the wheel after smoking. Some of them even believe that they’re better, more conscious drivers when they smoke. Nothing could be further from the truth.

We already know that marijuana slows down motor reaction and impacts critical thinking function, making stoned drivers a major liability on the road. When these users add alcohol into the equation, the results can be especially dangerous, because mixing the 2 substances greatly increases levels of THC in the bloodstream.

Alcohol and THC Levels

This new finding is part of a study published in the latest issue of the journal Clinical Chemistry.

Researchers analyzed data from 19 cannabis users who were split into 2 groups. The first group consumed a small amount of alcohol 10 minutes before inhaling vaporized cannabis, while the other group consumed a placebo before smoking.

The scientists found those who consumed alcohol had much higher levels of THC in their bloodstream than the placebo group. Because the alcohol group also showed greater levels of impairment than the placebo group, it was also concluded that using alcohol and marijuana together greatly increased the risk of a car crash compared to just using marijuana alone.

“The significantly higher blood THC … values with alcohol possibly explain increased performance impairment observed from cannabis-alcohol combinations,” said lead researcher Dr. Marilyn A. Huestis.

The greater risk of a car crash is due to increased levels of physical impairment.

The Increased Dangers of Poly-Substance Abuse

Another research project published last year in the Journal of Studies on Alcohol and Drugs found that teens who combined the 2 substances were more likely to display unsafe driving than those who only used 1 substance.

Teens who smoked pot and drank were 90% more likely to get a traffic ticket than teens who didn’t use either substance. They were also 50% more likely to be involved in a car crash.

Those who only used alcohol were 40% more likely to get a ticket and 20% more likely to be in a car crash than their non-substance using peers.

In addition to greater levels of physical impairment, mixing alcohol and pot also negatively impairs judgment. A study conducted last April by the Alcohol Research Group, a program of the Public Health Institute, noted that those who used pot and alcohol together were twice as likely to get behind the wheel as those who only consumed alcohol. They were also 6 times more likely to binge drink and 3 times as likely to experience negative consequences surrounding their substance use, including lost employment and legal trouble.

Although the abuse of marijuana should never be condoned, those who are planning to smoke should always designate a sober driver—it’s the only way to make sure that everyone gets home safely.

Protect yourself and those around you while on the road. When it’s all said and done, driving while high and/or drinking simply is never worth the risks.

Learn more about helping a loved one who’s addicted to marijuana or alcohol.

How to Get Help for Marijuana or Alcohol Addiction

If you or a loved one is struggling with a substance use issue, rest assured that help is available and recovery is possible. Professional drug and alcohol treatment can help anyone suffering with addiction learn to cope with life’s challenges without the use of substances. Please contact American Addiction Centers (AAC) free at for more information on treatment programs and rehab facilities near your location. You can also check your health insurance benefits using the form below.

Levels of Care in Alcohol and Marijuana Addiction Treatment

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