Purpose This paper aims to examine knowledge production and problem representation with regard to new psychoactive substances (NPS) in Her Majesty’s Chief Inspector of Prisons (HMCIP) annual reports. Design/methodology/approach Seven annual reports published by HMCIP for England and Wales between 2014 and 2020 have been systematically reviewed drawing on thematic analysis. Findings This paper demonstrates how framing in HMCIP annual reports produced a characterisation of NPS in prisons that inadvertently obstructed gender-sensitive knowledge production and problem representation. The framing formalised knowledge silences about spice in women’s prisons. Originality/value HMCIP annual reports monitor drugs in prisons and this affects how these spaces are represented to government and other stakeholders. This paper provides theoretical and practical insights into how gender-blind knowledge is produced by discussing examples of gender-blind drug representations in a specific policy context.