Multiple sclerosis (MS) is a disease that affects the central nervous system—the brain and spinal cord. It also affects the nerves to the eyes. Your nerve cells have a protective covering called myelin. Without myelin, the brain and spinal cord can't communicate with the nerves in the rest of the body. MS causes areas in the brain and spinal cord to get inflamed. It slowly damages the myelin and nerves in patches. These patches of damage are called lesions.

MS can cause problems with muscle strength, vision, balance, mood, and thinking. It may cause fatigue, pain, muscle spasms, numbness and tingling, and bowel and bladder problems.

MS tends to get worse over time. But this usually happens slowly. There is no cure for MS. But there are medicines and other treatments that might help slow its progression and treat symptoms.