Rationale: Previous treatment for macrophage activation syndrome (MAS) includes high-dose intravenous methylprednisolone along with intravenous immunoglobulin G. If MAS worsened, second-line therapy consisted of anakinra; if the disease remained refractory, third-line therapy with etoposide was considered. In addition, cyclosporine A plays a role in early MAS and in preventing recurrence. Some studies have reported the use of cytokine-targeting agents other than anakinra, such as canakinumab, tocilizumab, abatacept, and tofacitinib.Patient concerns: The patient with systemic lupus erythematosus (SLE) had an uncommon combination of intermittent fever, hyperferritinemia, hypertriglyceridemia, jaundice, and significantly abnormal liver function test results. The patient reported a history of daily fever of 38 to 39°C, painful oral ulcer, anorexia, abdominal bloating, diarrhea, and malar rash progression for 2 weeks, and jaundice, tea-colored urine, and clay-colored stool for 1 week preceding hospital admission.Diagnosis: SLE flareups in the patient were initially suspected. However, the final diagnosis was acute respiratory distress syndrome (ARDS) associated with MAS.Interventions: The treatment included disease-modifying antirheumatic drugs (DMARDs), such as azathioprine, and titrated steroid doses of methylprednisolone (40 mg q8 h) and dexamethasone (15 mg q8 h), after the patient had ARDS and was intubated.Dose-adjusted monotherapy with dexamethasone was found to be effective; this may be attributed to some DMARDs being unsuitable for cytokine storms, that is, some DMARDs may cause complications in cytokine storms.Outcomes: After dexamethasone 15 mg q8 h treatment, the patient's fever subsided within 2 days, and liver function became normal within 3 weeks. The patient regularly attended scheduled outpatient follow-up visits after discharge. After 2 years, the patient reported no symptoms or signs of SLE with 2 mg/d oral dexamethasone.Lessons: Early diagnosis of MAS and dexamethasone treatment for MAS with ARDS appear to be crucial for these patients.