BACKGROUND: Lapatinib, an FDA-approved tyrosine kinase inhibitor, treats HER2+ advanced/metastatic breast cancer. This study comprehensively analyzed its adverse reaction profile using FDA Adverse Event Reporting System (FAERS) to guide clinical use. RESEARCH DESIGN AND METHODS: Adverse event (AE) reports for lapatinib from the second quarter of 2007 to the second quarter of 2024 in FAERS were analyzed using Reporting Odds Ratio (ROR), Proportional Reporting Ratio (PRR), Multi-item Gamma Poisson Shrinkage (MGPS) and Bayesian Confidence Propagation Neural Network (BCPNN) to identify AE signals. RESULTS: Among 8300 AE reports, females (91.47%) and ages 40-59.9 (33.71%) were predominant. 20 system organ classifications (SOCs) were affected, with gastrointestinal disorders (ROR = 3.46) and skin disorders (ROR = 2.47) most significant. Based on the PT level, a total of 111 PTs were analyzed that met the four algorithms, including typical AEs such as diarrhea ( CONCLUSIONS: Lapatinib has a generally favorable safety profile, but gastrointestinal toxicity and dermatotoxicity require close monitoring to prevent serious AEs.