Diroximel fumarate is primarily used in the treatment of multiple sclerosis (MS), specifically for relapsing forms of the disease. It works by modulating the immune system to reduce inflammation and prevent nerve damage in the central nervous system. This helps in decreasing the frequency of relapses and slowing the progression of disability. Patients often find it easier to tolerate compared to other similar medications due to its improved gastrointestinal side effect profile. It is typically administered orally, making it a convenient option for long-term management of MS symptoms.