In order to choose the treatment that’s right for you, it’s important to understand a little about your type of multiple sclerosis (MS) and what to expect from your medication. Rebif® (interferon beta-1a) is a treatment for relapsing forms of multiple sclerosis (RMS), the most common type of MS.

RMS is an autoimmune disorder in which the body attacks itself. Specifically, the immune system attacks the coating (the myelin sheath) on the nerves in the brain, spinal cord, and eye area, which can cause scarring and prevent the nerves from communicating correctly. This communication breakdown can lead to symptoms of MS, which can vary in severity, and may lead to permanent damage.

Graphic showing the three kinds of immune cells that attack the neurons within the nervous system. Type 1 – Antigen presenting cells (APC); 2. T cells; and 3. B cells

Understanding lesions

When the body’s immune system attacks the covering of the nerves, it leaves scars called lesions. Technically, these are referred to as “sclerotic lesions,” which is where MS gets its name. Healthcare providers look for these lesions using magnetic resonance imaging (MRI) to help them diagnose RMS and select an appropriate treatment for their patients. Once a patient is taking a treatment, healthcare providers use MRI scans to judge how well that treatment is working. Rebif® (interferon beta-1a) has been proven in a clinical trial to reduce the number of new and enlarging MRI brain lesions—this is another one of the important goals of treating RMS.


How do healthcare providers look for lesions inside the body?

They use MRI scans.


Image of two MRI brain scans. The brain on the left has text that says – T1-weighted Gd-enhanced scan. The brain on the right has text that says – T2-weighted scan


MRI machines use magnets to see inside the brain and spinal cord to find lesions. There are 2 types of MRI scans usually used for people living with RMS. A T1-weighted gadolinium-enhanced (T1-Gd+) MRI supplies information about current disease activity by highlighting areas of active inflammation and permanent nerve damage, whereas a T2-weighted MRI image provides information about total disease burden (that is, both old and new lesions).


Relapses (flare-ups) and remissions

RMS is characterized by relapses and remissions.

  • Relapses—also called flare-ups, attacks, or exacerbations—occur when 1 or more RMS symptoms (such as numbness or blurred vision) appears or worsens, and remains for at least 24 hours

  • During the remission phase, the symptoms may partially or completely go away

In the chart below, you can see that a person’s abilities may not fully recover following a relapse.

Graph showing Relapses and Remission with Disability on the Y axis and Time on the X axis


  • Note that being in remission does not mean you no longer need your treatment. It is important to continue Rebif® as prescribed by your healthcare provider

  • Rebif® does not treat the symptoms of RMS, but has been proven in a clinical trial to help reduce the frequency of relapses. See study results showing reduced relapse rates with Rebif®

Measuring disability progression 

Disability progression is measured using the Expanded Disability Status Scale (EDSS). This is one method healthcare providers use to measure disability progression, especially in the clinical trial settings.


The EDSS and disability progression

Graphic of four people at different stages of disability from Fully Ambulatory to Impaired Walking Ability


Here’s how it works: After examining and assessing the patient, a healthcare provider assigns a number based on their level of disability. That score can be compared at a later date to measure any progression in the patient’s disability.

People who have EDSS scores from 1 to 4 are fully ambulatory, meaning they can still walk. For people with scores 5 or higher, their ability to walk will be increasingly impaired. In clinical trials, comparing scores over time can help researchers judge how well a treatment helps to slow disability progression—an important treatment goal.



About beta interferons

Beta interferons are proteins your body produces naturally in response to viral infection. They regulate the activity of immune cells like APCs, T cells, and B cells.

Rebif®, a form of interferon beta, is nearly identical to the kind produced in the body. Rebif® has the same amino acid sequence (the same protein structure) as naturally produced beta interferon.



Rebif® is a form of interferon beta, an immunomodulator which helps to regulate the immune system. Rebif® is similar to the type of interferon beta produced naturally in your body. When you have RMS, treatment with an interferon therapy may reduce the activity of cells that are attacking your nervous system.

Graphic of circles inside circles with the three types of immune cells in the outermost circle and the beta interferon in the smallest middle circle to demonstrate how Rebif® is thought to work


The precise way in which Rebif® works in MS is not known. Talk to your healthcare provider to find out what Rebif® may mean for you and your RMS.

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Discover why Rebif® may be right for treating your RMS

Get an overview of how Rebif® works, how Rebif® may help you meet MS treatment goals, how to take Rebif®, and more. To request a copy be mailed to you instead, call MS LifeLines® at 1-877-447-3243

Image of a healthcare professional talking to a patient with RMS

Start the discussion with your doctor

Get tips and questions to make the most of your office visit.


Important Safety Information

Do not take Rebif if you are allergic to interferon beta, human albumin, or any of the ingredients in Rebif.

Rebif can cause serious side effects. Tell your healthcare provider right away if you have any of the symptoms listed below while taking Rebif.

  • Behavioral health problems including depression and suicidal thoughts. You may have mood problems including depression (feeling hopeless or feeling bad about yourself), and thoughts of hurting yourself or suicide.
  • Liver problems or worsening of liver problems including liver failure. Symptoms may include nausea, loss of appetite, tiredness, dark colored urine and pale stools, yellowing of your skin or the white part of your eye, bleeding more easily than normal, confusion, and sleepiness. During your treatment with Rebif you will need to see your healthcare provider regularly and have regular blood tests to check for side effects.
  • Serious allergic and skin reactions. Symptoms may include itching, swelling of your face, eyes, lips, tongue or throat, trouble breathing, anxiousness, feeling faint, skin rash, hives, sores in your mouth, or skin blisters and peels.
  • Injection site problems. Rebif may cause redness, pain, itching or swelling at the place where your injection was given. Call your healthcare provider right away if an injection site becomes swollen and painful or the area looks infected. You may have a skin infection or an area of severe skin damage (necrosis) requiring treatment by a healthcare provider.
  • Blood problems. Rebif can affect your bone marrow and cause low red and white blood cell and platelet counts. In some people, these blood cell counts may fall to dangerously low levels. If your blood cell counts become very low, you can get infections and problems with bleeding and bruising. Your healthcare provider may ask you to have regular blood tests to check for blood problems.
  • Pulmonary arterial hypertension. Pulmonary arterial hypertension can occur with interferon beta products, including Rebif. Symptoms may include new or increasing fatigue or shortness of breath. Contact your healthcare provider right away if you develop these symptoms.
  • Seizures. Some people have had seizures while taking Rebif.

Before you take Rebif, tell your healthcare provider if you have or have had any of the following conditions:

  • mental illness, including depression and suicidal behavior
  • liver problems
  • bleeding problems or blood clots
  • low blood cell counts
  • seizures (epilepsy)
  • thyroid problems
  • drink alcohol
  • are pregnant or plan to become pregnant. It is not known if Rebif will harm your unborn baby. Tell your healthcare provider if you become pregnant during your treatment with Rebif
  • are breastfeeding or plan to breastfeed. Rebif may pass into your breastmilk. Talk with your healthcare provider about the best way to feed your baby if you take Rebif

Tell your healthcare provider about all medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements.

The most common side effects of Rebif include:

  • flu-like symptoms. You may have flu-like symptoms when you first start taking Rebif. You may be able to manage these flu-like symptoms by taking over-the-counter pain and fever reducers. For many people, these symptoms lessen or go away over time. Symptoms may include muscle aches, fever, tiredness, and chills
  • stomach pain
  • change in liver blood tests

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of Rebif. For more information, ask your healthcare provider or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or visit  www.fda.gov/medwatch.


Rebif® (interferon beta-1a) is a prescription medicine used to treat relapsing forms of multiple sclerosis, to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease, in adults. It is not known if Rebif is safe and effective in children.

Please see Rebif® Prescribing Information and Medication Guide.