Baclofen is used to treat pain and certain types of spasticity (muscle stiffness and tightness) from multiple sclerosis, spinal cord injuries, or other spinal cord diseases. Baclofen is in a class of medications called skeletal muscle relaxants. Baclofen acts on the spinal cord nerves and decreases the number and severity of muscle spasms caused by multiple sclerosis or spinal cord conditions. It also relieves pain and improves muscle movement.