Not all heroin users that enter the prison estate continue to use heroin or access opiate maintenance or detoxification treatment programmes. Some prisoners decide to self-detoxify. The literature on self-detoxification is thin and focuses on the decisions and practices of self-detoxification in community settings. Less attention has been given to the role of the body and the lived experience of self-detoxification in prison settings. The aim of this paper therefore is to examine the process of self-detoxification in prison, with a particular focus on the role of the body, embodiment and prisoner social relations. This paper draws on Drew Leder’s (1990) absent body theoretical framework and the literature on prison masculinity to analyse qualitative interviews with recently released prisoners. It shows how the decision to self-detoxify can be understood as part of the masculine performance of keeping a low profile. Keeping a low profile helped the participants minimise the risks of victimisation. The self-detoxification techniques the participants used were underpinned by an awareness of the body as poisoned by heroin, suffering because of its presence, rather than its absence. This study has implications for prisoners’ access to opiate maintenance and detoxification treatment programmes and harm reduction services upon release.