Introduction Alcohol is a major risk factor for heroin overdose, but the effects of alcohol consumption on other health and social outcomes for people who inject drugs have not been systematically evaluated. In this paper we explore the effects of alcohol on health and social outcomes for people who inject drugs.

Methods Data were obtained from 655 people who inject drugs as part of the Melbourne Injecting Drug User cohort study (MIX). AUDIT-C scores (0, 1–8, 8+) were generated and associations between these AUDIT-C scores and health and social outcomes were examined using logistic regression for dichotomous outcomes and linear regression for continuous outcomes.

Results While around 40% of the MIX cohort reported never drinking alcohol, 43% scored between 1 and 8 and 17% above 8 on the AUDIT-C. A score of 8+ on the AUDIT C was associated with a variety of negative health outcomes including non-fatal heroin overdose, as well as increased use of health services such as hospital emergency departments. Participants who reported drinking were more likely to report perpetrating violent crime, but were no more likely to report committing other sorts of crime such as fraud. Drinkers were more likely to report less overall life satisfaction than non-drinkers.

Conclusion The rate of abstinence in the MIX cohort was high, but those who reported drinking alcohol exhibited poorer health and social outcomes. Alcohol was associated with an increase in violent offending within a population with high rates of offending more generally.