This medication is used to treat a type of multiple sclerosis that occurs when symptoms appear in cycles of worsening and improvement (relapsingremitting multiple sclerosis-MS). It is a protein that is thought to work by preventing your immune system from attacking the nerves in your brain and spinal cord. This effect can decrease the number of periods of disease worsening (relapses) and prevent or delay disability. This drug is known as an immunomodulator.