ABSTRACT
Background: The World Health Organization (WHO) recommends using corticosteroids in patients with severe coronavirus disease 2019 (COVID-19) and acute respiratory distress syndrome (ARDS), and a large randomized controlled clinical trial in the UK found that dexamethasone was effective in reducing the number of deaths in patients with severe COVID-19.Case presentation: Herein, we described a case of COVID-19 with the clinical characteristics of the mild-symptomatic stage deteriorating to a critically ill state, who showed dramatic improvement with corticosteroids in the early stage of worsening of COVID-19 pneumonia.Discussion: This article further discusses the most suitable timing and dosage of corticosteroid to maximize its effect during the worsening of COVID-19 pneumonia.Learning points:• One of the main pathophysiological hypotheses for severe COVID-19 pneumonia is related to cytokine storm and viral load.• The clinical factors should be considered as the initial sign of a cytokine storm, and corticosteroid therapy may be useful in these patients.