Dasatinib is a second-generation drug that has revolutionized the treatment of chronic myeloid leukemia and acute lymphoblastic leukemia with the Philadelphia chromosome. The study analyzed the adverse effects of this drug using the US Adverse Event Reporting System (FAERS) based on 7,213 cases reported between the first quarter of 2004 and the fourth quarter of 2024. The most common adverse effects were pleural effusion (828 cases), hepatotoxicity (262 cases), and fluid retention (129 cases). The analysis revealed an early failure pattern, with 25.6% of adverse events occurring within 30 days and 28.2% after 360 days of treatment. The study also identified rare safety signals, including blast cell proliferation, primary effusion lymphoma, and bone marrow transplant complications. The results emphasize the need for intensive monitoring of patients at the start of treatment and continued follow-up during long-term dasatinib therapy.