Flexabenz Er 15 Mg is a muscle relaxer. It provides relief from the discomfort associated with acute, painful musculoskeletal conditions such as rigidity, tension, stiffness, and muscle spasms. Flexabenz Er 15 Mg should be taken with food. This will prevent you from getting an upset stomach. In general, you should try to use the smallest amount necessary to control your symptoms, for the shortest possible time. You should take this medicine regularly while you need it. Try not to miss doses as this will make the medicine less effective.