Many patients, especially those with long-term conditions, face significant challenges in managing their health. Burden of treatment is the effort required for self-managing health. This burden is often intensified by social determinants of health, such as limited access to care and financial instability. Burden of treatment is understudied in socially and medically complex patients, particularly in the critical period of transitioning home after hospital discharge. To address this gap, this study analyzed data from telephone interviews with urban primary care patients who had been recently hospitalized and were identified by an algorithm as having complex medical and social needs, and received a nurse-led outreach call intervention to examine the following areas: (a) how patients with complex health and social needs experience burden of treatment following hospitalization; (b) the individual, interpersonal, and healthcare system factors that patients perceive as impacting burden of treatment; and (c) the impact of an outreach phone call on burden of treatment. The study team completed telephone interviews with 22 patients who received the outreach call intervention, using a semi-structured interview guide based on established treatment burden measurement tools. Interview data were analyzed using rapid qualitative data analysis techniques to identify key themes to answer the research questions. Findings indicated that most participants reported minimal treatment burden across key domains, such as understanding diagnoses, scheduling appointments, managing medications, and engaging in self-care. A minority experienced substantial difficulties, such as frustration with appointment scheduling and challenges with activities of daily living due to their conditions. Several factors were identified as influencing treatment burden, including health condition complexity, family support, and provider communication. Patients generally responded positively to the outreach calls, finding them reassuring and informative. Treatment burden is variable among medically and socially complex patients following hospitalization and is shaped by a number of individual, interpersonal, and healthcare system factors. Further research is needed to develop and evaluate interventions to build healthcare system capacity to serve this population, to minimize treatment burden.