Accounts of health-related risk behaviour are generated in a social context of risk acceptability and moral responsibility. Drawing upon qualitative semi-structured interviews with injecting drug users (IDUs) in Belgrade, Serbia (n = 67) and Podgorica and Bar, Montenegro (n = 32), we explore drug injectors' accounts of sharing injecting equipment, and 'discriminative' and 'exceptional' sharing specifically, alongside accounts of hepatitis C risk. We find that accounts emphasize discriminative and exceptional sharing as acceptable given the circumstances, with normative syringe sharing presented as unacceptable and irresponsible. Two key themes emerged in descriptions of discriminative and exceptional sharing: 'trust' based in social relations, ensuring that sharing took place under 'reduced risk' conditions; and 'disruptions' to safety routine brought about by accidents, unexpected events, drug withdrawal and the environment. In accounts of environmental disruption, a lack of trust (and blame) was identified in relation to pharmacies and police. Whereas trust accounts justified sharing as reduced risk, disruption accounts accepted risk opportunity but appealed to a denial of agency. In addition, accounts portrayed a general context of risk and uncertainty in relation to hepatitis C, characterized by a lack of trust in knowledge about others' disclosed antibody status, a lack of faith in expert helping systems and confusion about HCV transmission.