Antibiotic use and immune-related adverse events in patients treated with immune checkpoint inhibitors: analysis of the FAERS database

Background: The use of antibiotics may influence the efficacy and toxicity of immune checkpoint inhibitors (ICIs) by altering the gut microbiota. However, current evidence on the link between antibiotic use and immune-related adverse events (irAEs) is limited. This study aims to evaluate whether antibiotics increase the risk of irAEs in ICI-treated patients and to examine their relationship to the timing of irAEs onset. Methods: We analyzed data from the FAERS database from 2014 to the fourth quarter of 2024. Using multivariable logistic regression and descriptive statistical analyses, we evaluated the association between antibiotic co-reporting and irAE reporting frequency and the timing across different antibiotic categories and ICIs regimens. Results: Our study included 155,157 patients treated with ICIs, of whom 9,518 (6.1%) received antibiotic therapy. Patients who used antibiotics had a significantly higher reported frequency risk of irAEs (OR = 1.17; 95%CI: 1.12-1.23; FDR