BackgroundThis systematic review and meta-analysis aimed to investigate the clinical efficacy and safety of systemic corticosteroids in the treatment of patients with severe community-acquired pneumonia (sCAP).MethodsA comprehensive search was conducted using the Medline, Embase, ClinicalTrials.gov, and Scopus databases for articles published until April 24, 2023. Only randomized controlled trials (RCTs) that assessed the clinical efficacy and safety of adjunctive corticosteroids for treating sCAP were included. The primary outcome was the 30-day all-cause mortality.ResultsA total of seven RCTs involving 1689 patients were included in this study. Overall, the study group had a lower mortality rate at day 30 than the control group (risk ratio [RR], 0.61; 95% CI 0.44 to 0.85;p< 0.01) with low heterogeneity (I2= 0%,p= 0.42). Compared to the control group, the study group had a lower risk of the requirement of mechanical ventilation (RR 0.57; 95% CI 0.45 to 0.73;p< 0.001), shorter length of intensive care unit (MD − 0.8; 95% CI − 1.4 to − 0.1;p= 0.02), and hospital stay (MD − 1.1; 95% CI − 2.0 to − 0.1;p= 0.04). Finally, no significant difference was observed between the study and the control groups in terms of gastrointestinal tract bleeding (RR 1.03; 95% CI 0.49 to 2.18;p= 0.93), healthcare-associated infection (RR 0.89; 95% CI 0.60 to 1.32;p= 0.56), and acute kidney injury (RR 0.68; 95% CI 0.21 to 2.26;p= 0.53).ConclusionsIn patients with sCAP, adjunctive corticosteroids can provide survival benefits and improve clinical outcomes without increasing adverse events. However, because the pooled evidence remains inconclusive, further studies are required.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13054-023-04561-z.