ObjectivesKRAS (G12C) inhibitors (sotorasib and adagrasib) have approved treatment in patients with KRAS (G12C)-mutated non-small cell lung cancer (NSCLC). The post-marketing data concerning KRAS (G12C) inhibitors remain limited, and the outcomes of relevant studies are yet to yield conclusive evidence supporting the long-term safety of KRAS (G12C) inhibitors. Materials and methodsThis investigation comprehensively assessed adverse events (AEs) attributed to KRAS (G12C) inhibitors by employing advanced data mining techniques, utilizing the FDA Adverse Event Reporting System (FAERS). The dataset encompasses the period from the first quarter of 2021 to the first quarter of 2024. A disproportionality analysis was conducted to quantify the correlation between KRAS (G12C) inhibitors and AEs. The metrics employed for the evaluation of disproportionality comprise the reporting odds ratio (ROR), the proportional reporting ratio (PRR), the information component (IC), and the empirical Bayesian geometric mean (EBGM). ResultsA total of 2,253 and 486 reports were identified as related to sotorasib and adagrasib, with the identification of 51 and 26 preferred terms, respectively. The most frequent AEs of sotorasib comprised diarrhoea (ROR 5.27), hepatotoxicity (ROR 38.09), alanine aminotransferase increased (ROR 17.41), aspartate aminotransferase increased (ROR 20.88), and hepatic function abnormal (ROR 19.88). The most common AEs of adagrasib included diarrhoea (ROR 4.21), nausea (ROR 3.84), vomiting (ROR 5.36), decreased appetite (ROR 4.79), and dehydration (ROR 7.00). A relatively reduced risk of hepatotoxicity but a increased risk of serious AEs in adagrasib compared to sotorasib (P < 0.001). ConclusionOur findings would provide valued evidence for healthcare professionals to recognize AEs associated with KRAS (G12C) inhibitors and differences between sotorasib and adagrasib, and guide their clinical practice.