Aim: The aim of the study was to assess switching disease-modifying therapy in patients with relapsing-remitting multiple sclerosis. Materials and methods: This observational single-centre study involved a retrospective evaluation of data of patients with relapsing-remitting multiple sclerosis receiving disease-modifying therapy under drug programmes reimbursed by the National Health Fund. Demographic data, the level of disability, disease activity and treatment methods were analysed with a particular emphasis on the reasons for switching the therapy. Results: Data were collected from patients with a mean age of 39.6 years, with women accounting for 68%. Therapy was switched in 32% (n = 118) of patients. In this group, 72% (n = 85) of patients modified their first-line treatment, and 28% (n = 33) required switching to a second-line drug. Treatment failure (52.5%, n = 62), followed by treatment intolerance (47.5%, n = 56) were the main reasons for switching. Patients on first line-treatment mostly required switching from interferon beta-1a, which was usually replaced with dimethyl fumarate and glatiramer acetate. The most common adverse events included skin reactions and needle fatigue, which were the most common reasons for switching treatment due to intolerance. Conclusions: The currently used immunomodulatory treatment is relatively well tolerated, and its failure is a more frequent reason for therapy switching. This indicates the need for diseasemodifying treatments that are highly effective, safe and well tolerated.

multiple sclerosis, immunomodulatory therapy, therapy switching, treatment failure, treatment intolerance