How Does Drinking Alcohol Affect Recovery From Another Drug Use Disorder?

There is an ongoing debate in the addiction field: Can people successfully recover from one drug use disorder if they continue to consume a different drug? In this case, authors reviewed more than a dozen studies in the field investigating specifically how drinking alcohol affects other drug use disorder treatment outcomes.


Addiction treatment studies often focus on one substance at a time – alcohol, marijuana, cocaine, or opioids for example. This makes sense from a research perspective because focusing on one substance makes it easier to understand the study’s findings. It may not be completely applicable to real-world situations, however.

More than a third of people in treatment have problems with both alcohol & another drug.


Also because the alcohol industry is generally commercialized and drinking is so common across North America, Europe, and Australia, even when the focus of a study is on an illicit drug, how drinking alcohol changes over time and affects other drug outcomes is important to understand. This research review helped tackle that issue by outlining findings from 13 studies investigating how people’s drinking changes if they sought treatment for another drug problem.


The study was a systematic review, meaning authors searched databases with a clear predetermined strategy and articles needed to meet certain criteria to be included in the review. In this case, the articles needed to be studies of drug treatment outcomes for adults (18+ years), that also measured drinking before and after treatment, as well as at a later follow-up measurement.

Thirteen studies conducted in several different countries met these criteria, including the Treatment Outcome Prospective Study, Drug Abuse Reporting Program, National Treatment Outcome Research Study, Australian Treatment Outcome Study, and Research Outcome Study.


There are two major theories around how alcohol use might be detrimental:


  1. Drinking-induced relapse: drinking could reduce inhibitions, and trigger (i.e., lead to) the feelings of reward familiar to those with substance use disorder, thereby possibly increasing craving for their primary drug; we refer to this phenomenon as drinking-inducing relapse (authors reviewed 5 studies related to this theory).
  2. Substitution Hypothesis: individuals might increase their drinking to compensate for the absence of their primary drug, in an attempt to substitute for the purpose of that drug (e.g., coping with difficult feelings) (authors reviewed 8 studies related to this theory).



This review suggested that there is more support for the drinking-induced relapse hypothesis than the substitution hypothesis.

Drinking-induced Relapse Studies:

Authors found support for the hypothesis that drinking alcohol is associated with greater use of the primary drug and greater likelihood of relapse to the primary drug use disorder, for which they received treatment.

For example, drinking was shown to be related to subsequent cocaine and other drug use both during and after treatment for the drug use disorder. Drinking after cocaine use disorder treatment was associated with worse cocaine outcomes 6 months later. On the other hand, alcohol abstinence during cocaine treatment is found to improve drug use outcomes over time.

Substitution Hypothesis:

The authors did not find support for the hypothesis that participants drink in order to provide an alternative coping strategy in place of their primary drug use disorder. There is little evidence that participants that are doing well in drug use disorder treatment are at higher risk for increasing their drinking as a substitute coping mechanism.


This is similar to a study reviewed in a previous RRI Bulletin. In that study authors used a large, representative sample to show that, for individuals with a substance use disorder, remission from that disorder reduces the risk of developing a new onset substance use disorder by 50% compared to individuals not in remission.

In other words, resolving one substance use problem makes it less likely they will develop another.

Although the reasons for this relationship are uncertain, it is possible that individuals acquired skills (e.g., via treatment, mutual-help, or personal experience) helping them resolve one problem that they could apply to making sure they did not develop another problem.

  1. One major issue with the studies outlined in this review is that they generally measured their primary drug outcomes and drinking with group averages. They did not report substance use at the individual level. Simply because there was no observable trend for alcohol and other drug use at the group level, does not mean that for a given individual their drinking increased in response to reducing or quitting their primary drug. This is called the ecological fallacy . Sophisticated statistical models that can measure these trends both at a group and individual level – like individual growth curve models – are needed to provide more comprehensive answers to questions around alcohol-induced relapse and the substitution hypothesis.

It seems based on this review that if someone resolves one drug use disorder – cocaine for example – it is much more likely that drinking alcohol will increase risk for relapse of the individual’s primary drug than being able to serve as a substitute.

Next steps might include understanding the mechanisms through which this drinking-induced relapse occurs and, conversely, why people who have positive drinking outcomes are also more likely to have better other drug outcomes as well. Given that in these studies, authors tended to control for demographic and important clinical factors (e.g., severity of their drug use disorder), it is unlikely simply that they had greater overall resources to help them attain and sustain abstinence (e.g., recovery capital) and, thus, are more likely to have good outcomes across the board. There are likely to be other processes at play.

In addition, given the changing landscape of recreational and medical marijuana legalization , another important area may be the impact of marijuana on other drug outcomes, just as was done in this review with alcohol.


  • For Individuals & families seeking recovery: Even if you are in treatment or received treatment for an illicit drug (i.e., not alcohol), it is unlikely that alcohol will serve as an effective “substitute” for your primary drug. In keeping with common clinical observations and personal testimony of individuals seeking recovery, this research review supports the notion that it is more likely that drinking could put you at risk for relapse back to your primary drug.
  • For scientists: While this systematic review was informative, lending support for alcohol-induced relapse to one’s primary drug – but not alcohol as a potential substitute for the primary drug –the studies outlined here generally examined alcohol and other drug use over time as a function of group averages. The field would benefit from studies that use statistical models where drinking over time can be modeled not only across individuals, but also within individuals. Longitudinal growth curve models are one potential statistical approach in this regard.
  • For policy makers: This systematic review suggests there is more scientific support for the relationship between drinking and poorer outcomes on one’s (non-alcohol) primary drug rather than increased drinking as a substitute. There are some important methodological limitations to the existing research that can help answer this question, however. Thus funding for more sophisticated research to specifically test this important clinical question could be important to the field.
  • For treatment professionals and treatment systems: Even for patients in treatment or having received treatment for another drug apart from alcohol, drinking could put them at risk for worse outcomes on the primary drug for which they initially sought treatment. Based on the scientific information available, clinicians may wish to advise their patients on the potential negative effects of drinking on recovery from their primary drug.


Staiger, P. K., Richardson, B., Long, C. M., Carr, V., & Marlatt, G. A. (2013). Overlooked and underestimated? Problematic alcohol use in clients recovering from drug dependence. Addiction, 108(7), 1188-1193.