Background: Myasthenic crisis (MC) and systemic lupus erythematosus (SLE) are distinct autoimmune conditions, each capable of leading to severe life-threatening complications. Their coexistence is rare, and their management becomes particularly difficult when they are triggered by infection and respiratory failure. This case report highlights the critical role of plasma exchange (PLEX) as a primary intervention for overlapping autoimmune crises.Case Report: We describe the case of a 57-year-old woman with a 15-year history of myasthenia gravis (MG) and a recent diagnosis of SLE who presented with progressive dyspnea and pneumonia. The patient’s condition rapidly deteriorated, requiring intubation and mechanical ventilation. She was categorized as having Myasthenia Gravis Foundation of America Class V MG with concurrent lupus flare. Early initiation of PLEX resulted in marked clinical improvement and successful extubation on day 5. Conclusion PLEX can play a pivotal role in the management of dual autoimmune crises. Prompt condition recognition and timely use of PLEX can significantly improve the outcomes of patients with MC complicated by SLE.