OBJECTIVES: Paroxysmal nocturnal hemoglobinuria (PNH) may develop breakthrough hemolysis (BTH) despite C5 inhibition. Although iptacopan, an oral factor B inhibitor, has demonstrated efficacy in phase 3 trials, switching from crovalimab has not been reported. We describe the first clinical case of this switch in a real-world clinical setting. METHODS: A 72-year-old man with long-standing PNH received eculizumab followed by crovalimab. Infectious enteritis triggered BTH and worsening anemia during crovalimab therapy. Because anemia persisted after recovery, iptacopan 200 mg twice daily was initiated three weeks after the final crovalimab administration. Clinical symptoms and laboratory parameters were followed for 12 months. This case report complied with the Declaration of Helsinki. RESULTS: Hemoglobin increased from 9.6 to 11.6 g/dL within two weeks and remained ≥12 g/dL thereafter. Dyspnea resolved within one week, vitality improved by two weeks, and no BTH or treatment-related adverse events occurred during follow-up. DISCUSSION: This case demonstrates the feasibility of switching from crovalimab to iptacopan despite the absence of an established method, and pharmacokinetic considerations guided the timing. CONCLUSION: Switching to iptacopan led to rapid and durable improvement in anemia and symptoms, supporting proximal complement inhibition as a valuable option for PNH patients inadequately controlled with C5 inhibitors.