BACKGROUND Diffuse alveolar hemorrhage (DAH) is a rare but life-threatening complication of systemic lupus erythematosus (SLE), with a mortality rate of up to 80%. It is seldom the initial manifestation of SLE, making early diagnosis and treatment challenging. DAH typically presents with hemoptysis, abrupt anemia, and diffuse pulmonary infiltrates, although up to 50% of cases lack hemoptysis, complicating diagnosis. CASE REPORT We present a case of a 23-year-old woman with no prior SLE diagnosis who presented with dyspnea, cough, and fever. Initial investigations revealed normocytic normochromic anemia (hemoglobin 7.3 g/dL), acute kidney injury (creatinine 323 µmol/L), and bilateral pulmonary infiltrates on imaging. DAH was confirmed via bronchoscopy, which showed hemorrhagic bronchoalveolar lavage fluid, and high-resolution computed tomography of the chest revealed pulmonary consolidations with peripheral sparing. Autoimmune workup confirmed SLE, with positive antinuclear antibodies, anti-dsDNA antibodies, and low complement levels. The patient was treated with high-dose corticosteroids, rituximab, and plasma exchange. Despite initial stabilization and weaning from mechanical ventilation, she developed refractory pancytopenia, posterior reversible encephalopathy syndrome, and multi-organ failure, leading to her death on hospital day 48. CONCLUSIONS This case stresses the value of a high index of suspicion for DAH in young women with respiratory symptoms, even in the absence of a known SLE diagnosis. Early diagnostic measures, including bronchoscopy and imaging, are critical for timely intervention. Aggressive immunosuppressive therapy and plasma exchange can stabilize patients temporarily, but refractory cases remain challenging. A multidisciplinary approach is essential to improve outcomes in this high-mortality condition.