Myorelax is used to treat pain caused by muscle spasms. It improves muscle movement and relieves pain and discomfort associated with these spasms. Myorelax is a combination pain reliever and muscle relaxant. It is used to relieve pain, inflammation and swelling related to muscles. It also helps relieve muscle stiffness or spasms, which improves muscle movement. Myorelax works by blocking chemicals in the brain that transmit signals associated with pain.