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What is Multiple Sclerosis (MS)?

About MS

Multiple sclerosis, or MS, is a chronic condition that affects the central nervous system (CNS): the brain, spinal cord and optic nerves. The damage caused by multiple sclerosis creates scars, called lesions, that can be seen on the brain, spinal cord and optic nerve. Because the process of developing these lesions is called sclerosis, multiple sclerosis literally means "many scars."

What happens in MS?

The central nervous system (CNS) is made up of nerve cells that send signals to each other. Each nerve cell is covered with a protective coating called myelin. Myelin acts as a conductor in helping signals move at high speeds from one end of the nerve cell to the other. In multiple sclerosis, disease activity damages the myelin in a process called demyelination. Demyelination results in lesions (or scars) that lead to a breakdown in signal transmissions.

The symptoms of multiple sclerosis (MS) are a result of this communication breakdown. Disease activity can also damage the underlying nerve cell, which may lead to permanent symptoms and disability.

What causes multiple sclerosis?

The cause of multiple sclerosis is currently unknown, although research is ongoing. It is generally believed that MS is an autoimmune disease. Normally, your immune system helps to fight foreign invaders such as viruses and bacteria. In an autoimmune disease, something triggers the immune system to attack itself. In the case of MS, the immune system is thought to attack and damage nerve cells and the myelin that covers them.

Other scientists think that multiple sclerosis may be triggered by an infection—probably a virus. It is thought that this trigger may activate the production of T cells, which are a type of white blood cell. Once activated, the T cells start to multiply and cross the blood-brain barrier (BBB) to the brain and spinal cord. The T cells are thought to then begin a process that attacks and damages nerve cells in the CNS. If there is a viral connection to multiple sclerosis, it is believed that the virus triggers a genetic predisposition to the disease, which means that exposure to a virus is just one factor for why someone might develop multiple sclerosis. There is also no evidence to support that MS is contagious.

Many think it's important to start therapy as early as possible after a diagnosis of relapsing MS.

If researchers can someday learn how and why people get MS, it may lead to breakthroughs in treatment or perhaps even prevention. Until then, there are disease-modifying drugs (DMDs), which are proven effective in reducing the frequency of relapses. Many think it's important to start therapy as early as possible after diagnosis of relapsing MS.

The American Academy of Neurology (AAN) and the National Multiple Sclerosis Society (NMSS) advise early treatment for active MS. Research shows that nerve damage starts early in MS. Once the nerve fiber is destroyed, it may be lost forever. Talk with your health care professional to find out which relapsing MS treatment is best for you. Start taking it as soon as you can.

Who gets multiple sclerosis (MS)?

  • More than 2.5 million people worldwide are thought to have some form of multiple sclerosis
  • An estimated 400,000 people in the United States are thought to have MS
  • More than twice as many women as men have MS
  • Most people are between 15 and 60 years of age when diagnosed with MS, although it can also occur in young children and significantly older adults
  • MS is more common in Caucasians and people of Northern European descent, but people from all backgrounds can be diagnosed with MS


Rebif® (interferon beta-1a) is used to treat relapsing forms of MS to decrease the frequency of relapses and delay the occurrence of some of the physical disability that is common in people with MS. Rebif is not approved for treatment of chronic progressive MS.

Important safety information

What is the most important information I should know about Rebif?

Rebif will not cure multiple sclerosis (MS) but it has been shown to decrease the number of flare-ups and slow the occurrence of some of the physical disability that is common in people with MS. Rebif can cause serious side effects, so before you start taking Rebif, you should talk with your doctor about the possible benefits of Rebif and its possible side effects to decide if Rebif is right for you. Potential serious side effects include:

  • Depression. Some patients treated with interferons, including Rebif, have become seriously depressed (feeling sad). Some patients have thought about killing themselves and a few have committed suicide. Depression (a sinking of spirits or sadness) is not uncommon in people with multiple sclerosis. However, if you are feeling noticeably sadder or helpless, or feel like hurting yourself or others, you should tell a family member or friend right away and call your doctor as soon as possible. Your doctor may ask that you stop using Rebif. You should also tell your doctor if you have ever had any mental illness, including depression, and if you take any medications for depression
  • Liver problems. Your liver may be affected by taking Rebif and a few patients have developed severe liver injury. Your health care provider may ask you to have regular blood tests to make sure that your liver is working properly. If your skin or the whites of your eyes become yellow or if you are bruising easily you should call your doctor right away
  • Risk to pregnancy. If you become pregnant while taking Rebif you should call your doctor right away. Rebif may cause you to lose your baby (miscarry) or may cause harm to your unborn child. You and your doctor will need to decide whether the potential benefit of taking Rebif is greater than the risks are to your unborn child
  • Allergic reactions. Some patients taking Rebif have had severe allergic reactions leading to difficulty breathing and loss of consciousness. Allergic reactions can happen after your first dose or may not happen until after you have taken Rebif many times. Less severe allergic reactions, such as itching, flushing or skin bumps, can also happen at any time. If you think you are having an allergic reaction, stop using Rebif immediately and call your doctor
  • Injection-site problems. Rebif may cause redness, pain or swelling at the place where an injection was given. Some patients have developed skin infections or areas of severe skin damage (necrosis) requiring treatment by a doctor. If one of your injection sites becomes swollen and painful or the area looks infected and it doesn’t heal within a few days, you should call your doctor. For more information, please see Medication Guide

Who should not take Rebif?

Do not take Rebif if you:

  • Have had an allergic reaction, such as difficulty breathing, flushing, or hives, to another interferon beta or to human albumin

If you have any of the following conditions or serious medical problems, you should tell your doctor before taking Rebif:

  • Depression (a sinking feeling or sadness), anxiety (feeling uneasy or fearful for no reason), or trouble sleeping
  • Liver diseases
  • Problems with your thyroid gland
  • Blood problems, such as bleeding or bruising easily, and anemia (low red blood cells) or low white blood cells
  • Epilepsy
  • Are planning to become pregnant

Tell your doctor about all medicines you take, including prescription and non-prescription medicines, vitamins and herbal supplements. Rebif and other medicines may affect each other, causing serious side effects. Talk to your doctor before you take any new medicines.

What are the possible side effects of Rebif?

  • Flu-like symptoms (fever, chills, sweating, muscle aches and tiredness)
  • Skin reactions. Soreness, redness, pain, bruising, or swelling may occur at the place of injection
  • Depression and anxiety. Some patients taking interferons have become very depressed and/or anxious
  • Liver problems
  • Abdominal pain
  • Blood problems. You may have a drop in the levels of infection-fighting blood cells, red blood cells or cells that help to form blood clots. If the drop in levels is severe, it can lessen your ability to fight infections, make you feel tired or sluggish or cause you to bruise or bleed easily
  • Thyroid problems. Your thyroid function may change. Symptoms of changes in the function of your thyroid include feeling cold or hot all the time, change in your weight (gain or loss) without a change in your diet or amount of exercise you are getting
  • Severe allergic reactions. Allergic reactions are rare and may be associated with difficulty in breathing and loss of consciousness, which require immediate medical attention

Let your doctor know if you have any of these symptoms or feel sad, tired, hot or cold, or experience hives, rashes, bruising, yellowing of the skin, or a change in body weight (gain or loss).

Refer to the Instructions for Use that comes with the Rebif® Rebidose® (interferon beta-1a) autoinjector.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call

This information is not intended to replace discussions with your doctor. For additional information about Rebif, please consult the Prescribing Information and Medication Guide and talk to your doctor. You can also visit www.rebif.com or call toll-free 1-877-447-3243. Rebif is available by prescription only.

MS LifeLines is an educational support service for people living with MS and their families. Speakers and MS LifeLines Ambassadors who participate in Talk MS or in live events are sponsored by EMD Serono, Inc. and Pfizer Inc. Rebif, Rebif Rebidose, Rebiject II, MS LifeLines, and the Rebif logo are registered trademarks of EMD Serono, Inc. or its affiliates.

Brought to you by EMD Serono, Inc. and Pfizer Inc, the co-marketers of Rebif in the US.

This information is intended only for residents of the United States.