Background/aims Multiple sclerosis is a progressive neurological disease that can significantly impact the psychosocial aspects of primary caregivers of individuals with multiple sclerosis. This study explored the process of social isolation among primary caregivers of individuals with multiple sclerosis in Kerman, Iran. Methods A grounded theory approach was employed to explore the various aspects of social isolation. Data were collected through unstructured and semi-structured interviews with 15 primary caregivers of individuals with multiple sclerosis, 13 individuals with multiple sclerosis and five health care providers who were selected based on purposeful and theoretical sampling. The data were analysed via constant comparative analysis. Results The core variable identified from the interviews was social isolation. Other concepts that were connected with this were: insufficient knowledge and awareness, escaping stigma, occupational difficulties, marital challenges and management of restrictions. Conclusions Social isolation can affect the wellbeing of primary caregivers of individuals with multiple sclerosis. Recognition and awareness of the process of social isolation and factors influencing it can be beneficial in designing theory-driven evaluation and intervention methods. It is recommended that rehabilitation specialists pay close attention to the common needs and interests of both individuals with multiple sclerosis and their primary caregivers.