Associations were examined between marijuana use and outcomes of treatment for alcohol dependence in about 1200 participants in an 18 week treatment program and a 1 year follow-up. Any use of marijuana resulted in lower abstinence from alcohol. Each day of cannabis use was associated with 4-5 days less abstinence from alcohol. This observation does not prove it causes more alcohol use, though.
PositiveTip: Avoid marijuana use during treatment for alcohol dependence.