OBJECTIVES This study explores trends in sex work among people who inject drugs (PWID) by gender and the relationship between sex work and adverse health outcomes including overdose, injection-site, and blood-borne virus (BBV) infections.

STUDY DESIGN The Unlinked Anonymous Monitoring Survey of PWID is an annual cross-sectional survey that monitors BBV prevalence and behaviours, including transactional sex, among PWID recruited through specialist services in England, Wales, and Northern Ireland.

METHODS Trends in sex work among PWID (2011-2021) were described. Data were analysed to assess differences between PWID who engaged in sex work in the past year (sex workers [SWs]) and those who did not (non-SWs) by gender (Pearson Chi tests) (2018-2021). Associations between sex work in the past year and adverse health outcomes were investigated using logistic regression.

RESULTS Between 2011 and 2021, sex work among PWID remained stable, with 31% of women and 6.3% of men who inject, reporting having ever engaged in sex work, and 14% of women and 2.2% of men engaging in sex work in the past year. Between 2018 and 2021, SWs had greater odds of reporting symptoms of an injection-site infection (adjusted odds ratio (aOR): 1.68 [95% confidence interval {CI}: 1.31-2.16], P < 0.001) and reporting overdose (aOR: 2.21 [CI: 1.74-2.80], P < 0.001) than non-SWs had in the past year. Among men, SWs had 243% greater odds of having HIV than non-SWs (aOR: 3.43 [CI: 1.03-11.33], P = 0.043).

CONCLUSIONS Our findings highlight disproportionate vulnerability and intersection of overlapping risk factors experienced by PWID SWs and a need for tailored interventions which are inclusive and low-threshold.