Active = active disease course revealed periods of relapses (attacks) and seen on an MRI with contrast. Active MS is usually treated with medication to prevent attacks. There are two reasons why MS is inactive. The first is that the medication used to prevent attacks is working. The second reason is that the disease has run its course. Be aware that if you stop a medication thinking your disease is no longer active, you may discover it was more aggressive than you thought. You also might not have another exacerbation. Each person must evaluate their own risk vs. reward.