Peginterferon beta-1a for the treatment of relapsing multiple sclerosis: A case series

•Few real-world reports of patients initiating peginterferon beta-1a are available.•Positive outcomes were reported when starting/switching to peginterferon beta-1a.•Education is key to tolerability of flu-like symptoms and injection site reactions Interferon beta therapies have been effective in the treatment of relapsing forms of multiple sclerosis for over 2 decades. These therapies have varying routes and schedules of administration but broadly similar clinical and radiologic efficacy. The most commonly reported adverse effects are flu-like symptoms and injection site reactions. The most recent addition to the class is peginterferon beta-1a, which is administered subcutaneously every 2 weeks. Although clinically stable patients with multiple sclerosis may switch between platform therapies (such as interferons) based on tolerability or personal preference, few studies have explored the outcomes of switching. Herein I present 3 cases of patients who either initiated therapy with peginterferon beta-1a or switched from another interferon and had positive outcomes. With appropriate patient education and expectation setting regarding potential flu-like symptoms and injection-site reactions, peginterferon beta-1a may be a beneficial alternative for patients who prefer less frequent injections.