Muscle relaxant Pain O Soma 350 mg  acts by preventing pain signals from reaching the brain from nerves. Pain o Soma is used in concert with physical therapy and sleep to treat skeletal muscle issues, including pain or injury. It is a muscle relaxant that acts by preventing the brain and neurons from receiving pain signals. Because most skeletal muscle injuries are usually temporary and there is limited proof of Soma's long-term benefits, it should only be administered for short periods.