Introduction Sex work and drug use are inextricably linked. For drug dependent street sex workers (SSWs) it is the need to fund drug use that warrants exposure to the risks of selling sex. Despite evidence that SSWs have poor outcomes from drug treatment services, the recent recovery-orientated UK drug strategy did not identify SSWs as a group with complex treatment needs. Synthesis and critical appraisal of existing evidence is needed to guide service changes towards improving drug treatment outcomes for this group.

Methods A systematic review of evidence of effectiveness of interventions to reduce illicit drug use in female SSWs experiencing problematic drug use was undertaken. Following the PRISMA guidelines, a structured search strategy was used. Searches included databases, organisational and government websites to identify published and grey literature, as well as hand-searching reference lists and journals and contacting experts in the field.

Results Six studies, one experimental and five observational, were identified which met review inclusion criteria. Intervention approaches evaluated included substitute prescribing, educational sessions and motivational interviewing. All studies reported a positive intervention effect but the five observational studies were all subject to a relatively high risk of bias. By contrast, the only experimental study, provided little or no evidence of positive effect (odds ratio for reduction of illicit drug in intervention compared to controls 1.17 95% CI 0.84–1.66 at 3 months and 1.14 (95% CI 0.8–1.61) at six months follow-up). All studies described challenges and solutions to study recruitment, retention and follow-up which were influenced by issues affecting SSWs’ health and social stability.

Conclusion There is currently no strong evidence for effectiveness of interventions to reduce illicit drug use in drug dependent female SSWs. The development and robust evaluation of effective interventions should be a priority if recovery is to become a realistic goal for this complex group. The first author is funded by an NIHR postdoctoral fellowship. No pharmaceutical grants were received in the development of this study.