BackgroundMultiple sclerosis (MS) is a chronic, inflammatory progressive demyelinating disease of the central nervous system. MS is one of the main causes of disability among young adults, and its management is a serious challenge for the healthcare system.PurposeThe main purpose of this study was to examine adherence to first-line disease-modifying therapy (DMT) in MS patients using the self-report Multiple Sclerosis Treatment Adherence Questionnaire (MS-TAQ).Materials and methodsThe participants consisted of 226 MS patients (166 women and 60 men) who were treated with first-line immunomodulatory DMT. This study used a questionnaire designed by the authors, which contained questions about sociodemographic data, and the Polish version of the MS-TAQ.ResultsThe overall adherence was 76.5% according to the first criterion (missed ≥1 injection or tablet). There were no statistically significant differences due to sociodemographic variables between adherent and nonadherent patients. However, patients taking Avonex® significantly more often belonged to the adherent group (P=0.042). The most frequently mentioned reasons why nonadherent patients forget to take the drug included the following: too busy in their daily activities, indisposition to take the drug, unwillingness to take the drug, interference with daily activities, and dissatisfaction with the drug. The degree of adherence among MS patients treated with immunomodulatory drugs is high; however, some patients do not take medications regularly.ConclusionDue to the utility of the MS-TAQ, the caregivers of MS patients are able to quickly and easily assess the occurrence of side effects, ways to cope with them, and the occurrence of barriers to taking medication.