Heroin is one of the most commonly injected illicit substances worldwide [1,2]. Heroin injection is associated with a range of harms including poor health [3,4], poor psychosocial functioning [5] and increased risk of fatal and non-fatal heroin overdose [6,7]. Heroin injection is also a significant risk factor for blood-borne viral infections (BBVI) such as hepatitis C, hepatitis B and HIV [8-12]. Despite these harms little is known about initiation to heroin injecting.
