CBD and alcohol: four human trials, no protective effect

The story begins with a trial published in 1979 in Psychopharmacology. Consroe and colleagues gave ten healthy volunteers, six men and four women, four treatments one week apart: a placebo, 200 mg of CBD, alcohol at 1 g per kilo of body weight, and alcohol with CBD. Neither the volunteers nor the investigators knew which treatment was being given.

The trial produced two results. Alcohol, with or without CBD, impaired motor and psychomotor performance, while CBD alone did not. The combination also gave a lower breathalyser reading than alcohol alone. Yet the authors noted few differences in effects between the two alcohol conditions. They put their finding in one sentence: CBD's inactivity on performance extends to its interaction with alcohol.

The blood alcohol reading went down while the effects of alcohol stayed the same. This single observation, almost fifty years old, is still where the sales pitch comes from.

Three teams have since returned to the question with larger protocols.

Karoly's 2023 trial is the closest to the 1979 question. Thirty-six people who reported heavy drinking took 30 mg of CBD, 200 mg or a placebo before a standardised dose of alcohol. The authors recorded small gaps: blood alcohol fell slightly faster on placebo, and the felt stimulation faded more slowly on 200 mg. They concluded that CBD has minimal influence on breath alcohol and the subjective effects of alcohol, with differences of "trivial" size.

Mueller's trial, published in 2025 in Frontiers in Psychiatry, followed 44 adults with moderate to severe alcohol use disorder for eight weeks. They took 150 mg a day of full-spectrum CBD, broad-spectrum CBD or a placebo. The trial found no effect of the treatment on drinks per drinking day. The full-spectrum group reported less craving at 8 and 16 weeks; with groups of 13 to 16 people, the authors treat this signal as preliminary.

The latest, published in June 2026 in the Journal of Cannabis Research, is a phase I safety trial. Of twenty-nine adults enrolled, nineteen completed it. The researchers found no difference in peak breath alcohol or in its time course between CBD doses, and none in sedation or craving.

The promises of "protection" have another source: rodents. A French review published in 2019 in Frontiers in Pharmacology brings this work together. In animals, CBD reduces alcohol intake and alcohol-related fatty liver and liver fibrosis, along with some brain damage. The authors write that any other use would need trials in humans.

Those human trials have confirmed nothing so far. In 2025, a Sorbonne University team published an umbrella review of 22 systematic reviews in Addiction. It concludes that CBD on its own does not appear effective for substance use disorders, and judges the evidence for alcohol limited and inconclusive. A result in rats does not automatically hold in humans; clinical trials exist to check exactly that.

On the liver, the Epidyolex label points to caution. This medicine was given at 10 to 25 mg per kilo per day in its controlled trials. Liver enzymes (ALT) rose above three times the upper limit of normal in 12% of patients on cannabidiol, against less than 1% on placebo. Those doses bear no comparison with an everyday oil. Our article on CBD and liver enzymes goes through these figures.

The most precise document on the question is the summary of product characteristics for Epidyolex, published by the European Medicines Agency. It states that cannabidiol can cause somnolence and sedation, and that other central nervous system depressants, including alcohol, can increase this effect. It also rates cannabidiol as having a major influence on the ability to drive.

That text covers a high-dose medicine prescribed for rare epilepsies; our file on Epidyolex has the details. The mechanism holds whatever the bottle, since two substances that can make you drowsy do not cancel each other out. The 2023 and 2026 trials, at 30 to 200 mg, measured no extra sedation, which still does not rule out the effect in a given person.

CBD also acts on the liver enzymes that break down many medicines. If you take a treatment, the article on the grapefruit effect explains why you should talk to your doctor or pharmacist.

In France, driving after drug use is punished whatever the amount detected, as the “Drogue au volant” page on service-public.fr reminds readers. A CBD product may contain traces of THC, up to 0.30% in the finished product, and roadside saliva tests target THC and ignore CBD. Our guide to saliva drug testing describes what the tests detect.

Driving after drug use carries 3 years in prison and a €9,000 fine. With alcohol as well, the penalty rises to 5 years in prison and a €15,000 fine, and 9 licence points are removed, against 6. Given the possible drowsiness and the legal risk, the practical rule is simple: if you have combined the two, do not drive.

CBD changes nothing in the guidelines of Santé publique France, the French public health agency. It recommends no more than 10 standard drinks a week and no more than 2 a day, with days without alcohol. In France a standard drink holds 10 g of pure alcohol, whether wine, beer or spirits. The agency also stresses that no level of drinking is free of risk.

We found no position from the ANSM, the HAS or Inserm on combining CBD and alcohol specifically. For a broader comparison of the two substances, see our article alcohol and cannabis: which is more harmful.