Abstract: In 2001, a large and sustained supply shock halted a heroin epidemic in Australia. We use treatment records to identify 27,467 opioid users and examine how this shock affected their health and criminal activity over the next eight years. An initial decrease in mortality is offset by substitution to other drugs and an increase in crime. Most adverse effects dissipate after one year, and are followed by continued mortality improvements and a large decrease in property crime. Our results demonstrate that reducing the supply of illicit opioids can lead to meaningful longer-term improvements, even when the short-term effects are ambiguous.