**18. Corticosteroids**

Corticosteroids are used to reduce the host's inflammatory process in the lungs, which can contribute to acute lung damage and acute respiratory distress syndrome (ARDS). COVID-19 induces severe endothelial and alveolar damage as a result of host-mediated excessive inflammation and cytokine storm [7]. Excessive inflammation and an unregulated immunological response are the major causes of COVID-19 related death [112]. Corticosteroids are extensively used and well tolerated over the world. They have the potential to minimize the risk of cytokine storms and inflammation in COVID-19 [113]. They may also be able to control the course of respiratory failure and mortality by regulating inflammation-mediated lung damage [113, 114]. Previous research regarding the efficacy of corticosteroid therapy in severe pneumonia [115] revealed a link between corticosteroid usage and a lower risk of ARDS, as well as shorter hospital stay duration [116]. However, corticosteroids have the potential to greatly reduce the use of mechanical ventilation required in COVID-19 patients while also limiting major side effects. Additionally, for individuals with COVID-19, a pulse dosage of methylprednisolone for fewer than 7 days may be a useful therapy strategy [117].

However, side effects such as delayed virus clearance and an increased risk of subsequent infection may balance this advantage. In an observational study, no link has been found between corticosteroids and high survival rate in patients with SARS and MERS but reported a link between delayed virus clearance and high incidence of comorbidities such as hyperglycemia, psychosis, and avascular necrosis [102, 118]. Moreover, a meta-analysis of 10 observational studies of 6548 patients with influenza pneumonia in 2019 found that corticosteroids were linked to an increased risk of death and twice the risk of secondary infection [119]. While the effectiveness of corticosteroids in ARDS and septic shock is generally controversial, Russell and colleagues [120] claimed that individuals with bacterial infection are more likely to benefit from corticosteroids than those with viral infections. The data currently supports the use of corticosteroids in COVID-19 patients; however, additional study is needed on the type, dose, start time, and duration.
