Measures to control the spread of Covid-19 are challenging social work practice in terms of difficulties to deliver services to vulnerable groups. The aim of this study was to investigate how the Covid-19 pandemic affected social work with people who use drugs regarding ways of working, quality of work, accessibility, and staff motivation. A mixed methods approach was used which included an online survey (n = 81), and three qualitative focus group sessions with social workers in the field of addiction. We analysed the quantitative data through frequency calculations, cross tabulations and Pearson’s χ2 test, and the qualitative data with qualitative textual analysis. The demand for physical distancing challenged important principles of social work such as social closeness, trust and accessibility, and led to a difficult work environment and fewer opportunities to conduct high quality social work, as well as a reduced likelihood of vulnerable clients receiving adequate assistance. Altered practices concerning client meetings negatively affected assessments, working alliances as well as motivation and energy in social work practice. Social workers on the frontline became the ‘last outpost’ when other services shut down, and ‘digital bridges’ between clients and other social workers. Social workers faced a difficult trade-off between protecting themselves and clients from the risk of infection and providing support to a vulnerable group. There were also examples of new practices and lessons learned, for example, the introduction of ‘walks and talks’ with clients and an increased knowledge of how and when to use digital tools for communication.