Short-term and long-term safety and tolerability of interferon β-1b in multiple sclerosis.

Clinical trials have generated a wealth of data on the safety profile of interferon β-1b for patients with multiple sclerosis (MS). In general, interferon β-1b has not been associated with serious or life-threatening side effects during long-term treatment. Flu-like symptoms, injection site reactions, depression, and elevated liver transaminases were the most common adverse events in clinical trials. This review will discuss the rates of these and other common adverse events observed in 3 clinical trials of interferon β-1b: BENEFIT, BEYOND, and the 16-year Long-Term Follow-up (LTF) of the pivotal interferon β-1b trial in MS, as well as how these adverse events may influence patient and physician decision making when selecting a disease-modifying therapy. In addition, we will discuss the effects of interferon β-1b on mortality in the 16-year and 21-year LTF studies.