Most drug abuse treatment programs advise marijuana users who are trying to stop or reduce their marijuana use, to either not use alcohol or to watch out for a possible increase in alcohol use. Since no one has tested it before, our group tested whether stopping marijuana would increase alcohol use (Peters et al, Drug and Alcohol Dependence 106, p 111-118, 2010; see link below). Twenty-eight daily marijuana users smoked their marijuana as usual for one week, then we paid them not to use marijuana for two weeks (and tested them to make sure they did not use), and then let them go back to their marijuana use for final week. Among marijuana users without past alcohol problems, alcohol use did not increase; however, among those with past alcohol problems, their alcohol use increased by 50% from 2.5 drinks/day to 3.7 drinks per day. Marijuana users who had more marijuana withdrawal symptoms (e.g. irritability) also increased their alcohol more. Perhaps they were using alcohol to treat their withdrawal symptoms. Among the tobacco smokers, their smoking did not increase during marijuana abstinence. We point out that the study did not test whether the increase in alcohol use caused problems or interfered with the ability of users to stop or reduce. Nevertheless, our results suggest that if you have had alcohol problems or had severe marijuana withdrawal symptoms in the past, you should watch out for your alcohol use increasing if you stop or reduce marijuana use.
–Dr. John R. Hughes