Fostamatinib is primarily used as a therapeutic agent in the treatment of autoimmune diseases, particularly chronic immune thrombocytopenia (ITP). It functions by inhibiting spleen tyrosine kinase (Syk), which plays a key role in immune receptor signaling pathways. By blocking Syk, fostamatinib reduces the immune system’s attack on platelets, helping to increase platelet counts in patients who have not responded adequately to other treatments such as corticosteroids or splenectomy. It has also been investigated for use in other autoimmune and inflammatory conditions, including rheumatoid arthritis, where modulation of immune cell activation can help reduce joint inflammation and tissue damage. Additionally, fostamatinib shows potential in certain hematologic disorders and is being studied in the context of inflammatory responses in diseases with dysregulated immunity. Its oral bioavailability makes it a practical option for long-term management in outpatient settings.