A decrease in the age of initiation to drug use, including heroin use, across birth cohorts has been documented in both Australia [17,18] and the United States [19]. This decrease in the age of heroin initiation has been associated with greater poly drug use, unintentional overdose and criminal behaviour, independent of years of heroin use [17]. Better understanding of the circumstances surrounding initiation to injecting heroin use is needed if appropriate interventions are to be formulated.
