Dexamethasone has never been evaluated in ARDS in a randomized controlled fashion. However, dexametasone has potent anti-inflammatory effects and weak mineralocorticoid effects compared with other corticosteroids. Dexamethasone has a long-lasting effect, allowing for a once-a-day regimen. Whether addition of dexamethasone to conventional supportive treatment benefits ARDS patients is unknown, it has been used in patients with sepsis, septic shock, pneumonia, trauma, and meningitis, all of them causes of ARDS.