This study provides a detailed description of the drug purchase and drug use patterns of a cohort of people who inject drugs, and an understanding of changes that occurred between 2009 and 2014. During this period, heroin, methamphetamine, benzodiazepines and other opioids were typically purchased between 10am and 2pm with very little search time, were used almost immediately following their acquisition, and sharing a purchase or pooling money with a partner or friend was common, as were larger (>$100) purchases. Reported drug purchases and drug use both occurred more frequently in private homes than public settings, and this became increasingly so over time. Although the primary drug of the cohort remained heroin, two trends in drug use were observed: a transition from heroin to cannabis use; and a transition from powder to crystal methamphetamine use and increased methamphetamine consumption, corresponding with increased availability of the crystal form and a dramatic decrease in purity-adjusted price. (Abstract, edited)