Multiple sclerosis, often called MS, is a disease that affects the central nervous system—the brain, spinal cord, and optic nerves. It can cause problems with muscle control and strength, vision, balance, feeling, and thinking.

Your nerve fibers 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 slowly destroys myelin and nerve cells in the central nervous system, causing muscle weakness and other symptoms.

Most of the time, MS is not diagnosed unless a doctor can be sure you have had at least two attacks affecting at least two different areas of your central nervous system . Your doctor will examine you, ask you questions about your symptoms, and do some tests. An MRI scan is often used to confirm the diagnosis, because the patches of damage (lesions) caused by MS attacks can be seen with MRI.

MS is different for each person. You may go through life with only minor problems. Or you may become seriously disabled. Most people are somewhere in between. In general, MS follows one of four courses:

• Relapsing-remitting, which means symptoms fade and then return off and on for many years.
• Secondary progressive, which at first follows a relapsing-remitting course and then becomes progressively worse. "Progressive" means it gets worse over time.
• Primary progressive, which means the disease is progressive from the start.
• Progressive relapsing, which means the symptoms are progressive at first and are relapsing later.

Disease-modifying therapy means treatment to delay, change, or interrupt the natural course of the disease. For MS, this means taking medicine over a long period of time to reduce not only the number of attacks but also how bad they are.

To slow down the spread of MS, your doctor may suggest medicines after your first attack or when you are first diagnosed with MS. People treated soon after being diagnosed with MS may have better results than those who delay treatment. Lasting damage to the nervous system can occur in the early stages of MS. Early treatment may prevent or delay some of this damage.

Medicines for MS can be costly. They don't work for everyone. And it's hard to know who will benefit.

Medicines used for MS include:

• Interferon beta (such as Betaseron).
• Glatiramer (Copaxone).
• Fingolimod (Gilenya).

Making a decision about starting disease-modifying therapy can be hard, especially if your symptoms have been mild. Some people wait to see if their symptoms get worse before they make a decision to start therapy. A small number of people with MS may never have more than a few mild episodes and never have any disability. But there is no way to know who will fall into this group.

Medicines can't cure MS. They don't stop disease activity or reverse nervous system damage that has already happened. But drugs may reduce relapses and delay disability in many people with relapsing forms of MS.

For people who have relapsing-remitting MS:

• Interferon beta can reduce how often you have relapses and how bad those relapses are. These drugs may also delay disability in some people and may limit new patches of damage (lesions).¹
• Glatiramer can make relapses less severe. It can also reduce how often you have them, like the interferon beta drugs. It also slows the number of new lesions and decreases the chances of disability.²
• Fingolimod can reduce how often you have relapses.³ It is the only medicine for MS that you can take by mouth (oral).

If you decide not to take MS medicines, there are some other things you can do.

• Take other medicine, such as steroid medicine, to relieve symptoms during attacks or relapses.
• Try physical therapy, occupational therapy, and other treatment you can do at home to help you manage your symptoms and adjust to living and working with MS.
• Do what you can to stay well. Eat a healthy diet, get plenty of rest, and try to reduce stress.

Your doctor may suggest that you take MS medicines because:

• You have had symptoms that are most likely caused by multiple sclerosis, tests show you most likely have MS, and your doctor is confident that you have MS.
• You have just been diagnosed with multiple sclerosis, and early treatment may delay damage to your central nervous system.
• These medicines are the only ones proved to reduce the frequency and severity of relapses and delay disability.