In recent years, there has been a steady increase in the number of people receiving immunosuppressive treatment. The ongoing development of these therapies, although effective in controlling autoimmune disease, brings with it new diagnostic and therapeutic challenges due to complex modulation of cellular and humoral responses. Despite significant therapeutic benefits, their use is associated with the risk of developing opportunistic infections, which are almost unrecognised in immunocompetent persons. We present a case of neuroinfection caused by Listeria monocytogenes complicated by brain abscess in an autoimmune hepatitis female patient treated with prednisone and mercaptopurine. Importantly, the disease initially presented with non-specific neurological symptoms, which might have delayed diagnosis. Nevertheless, an early lumbar puncture, cerebrospinal fluid testing with identification of the most common pathogens, and imaging tests allowed for diagnosis and implementation of appropriate antibiotic therapy, which resulted in the expected clinical improvement. This case highlights that patients receiving immunosuppressive therapy may develop serious opportunistic infections, and early diagnosis and implementation of right treatment are crucial for improving prognosis and minimising complications.