Injection risk behaviors at the first and at the most recent injections among drug users.

Risk behaviors at the first intravenous substance injection are unknown. A structured questionnaire was used to investigate the circumstances of the first injection and the changes in risk behaviors between the first and the most recent injections in a group of 143 intravenous drug users (IDUs). When they first injected most subjects were not alone, the initiator was an IDU (94%) who prepared the injection (76%) and did it (79%). The proportions of IDUs sharing preparation equipment (58 vs. 14%), borrowing (23 vs. 2%) and lending injecting equipment (26 vs. 4%) decreased between the first and the most recent injection.