Background and aim Peginterferon beta-1a (Plegridy) offers the advantage of a prolonged half-life with less-frequent administration and a higher patient adherence. However, the use of an interferon may lead to flu-like symptoms (FLS) and injection-site reactions (ISR) that results in drug discontinuation. The objective of this Delphi analysis was to obtain consensus on the characteristics and management of FLS/ISR of peginterferon beta-1a in patients with relapsing-remitting MS based on real-world clinical experiences.4 Methods A steering committee of MS neurologists and nurses identified issues regarding the features and management of adverse events and generated a questionnaire used to conduct three rounds of the Delphi web survey with an Italian expert panel (54 neurologists and nurses). Results Fifty-three (100%), fifty-one (96.22%), and forty-two (79.24%) responders completed questionnaires 1, 2, and 3 respectively. Responders reported that, during the first 6 months of treatment, FLS generally occurred 6–12 h after injection; the fever tended to resolve after 12–24 h; otherwise, FLS lasted up to 48 h. FLS improved or disappeared after 6 months of treatment in most cases. Paracetamol was recommended as the first choice for managing FLS. Erythema was the most common ISR and usually resolved within 1 week after injection. Responders reported that the adherence to treatment increases after adequate patient education on the drug’s tolerability profile. Conclusions Patient education and counseling play a key role in promoting adherence to treatment especially in the first months also in patients switching from nonpegylated IFNs to peginterferon beta-1a.