Rebif (interferon beta 1a)

Rebif (interferon beta 1a) is a disease modifying drug (DMD) for relapsing remitting MS.

You self-inject Rebif under the skin three times a week to reduce the number and severity of relapses. It reduces the number of relapses by about one third (30%).

Common side effects include flu-like symptoms and injection site reactions.

What is Rebif used for in MS?

Rebif is a disease modifying drug (DMD) for relapsing remitting MS. You have fewer relapses than you might have had with no treatment and any relapses you do have should be less severe. 

Rebif is a moderately effective (category 1.1) DMD; in clinical trials people taking Rebif had about 30% fewer relapses than people taking placebo. In clinical trials, MRI scans showed people taking Rebif had fewer, smaller or no new areas of active MS (lesions). Rebif may also slow down the build-up of disability associated with MS.

Who can take Rebif?

Rebif can be prescribed for adults with active relapsing remitting MS.

Rebif has been approved for use on the NHS since 2002. It can only be prescribed by a neurologist.


It's important that you tell your MS team if you have any health problems or are taking other medicines. Rebif may not be suitable if you have severe depression or suicidal thoughts.

Conception and pregnancy

The prescribing advice for Rebif during pregnancy and breastfeeding is appropriately cautious.  However, pregnancy registers and clinical experience have shown no increased risk to the health of mother or baby with Rebif.

If you are trying for a family, talk to your MS nurse or neurologist about whether you should continue to take Rebif until you are pregnant.

If you become pregnant while on Rebif, your neurologist or MS nurse may recommend you stop taking it, depending on how active your MS has been and the benefits and risks to you and your baby. Women usually experience fewer relapses during pregnancy, so continuing to take Rebif may not be necessary.  However, if Rebif is stopped during pregnancy, it will take several months to reach full effectiveness when restarted and may not reduce relapses during the first few months after childbirth.

Pregnancy guidelines consider that it is safe to take Rebif during breastfeeding if required. 

How do I take Rebif?

You self-inject Rebif under the skin three times a week. Rebif is supplied in several different formats - your MS nurse can explain the different injection devices and help you choose the most appropriate one for you.

Your MS nurse will show you how to do the injections, discuss the practicalities and offer advice or training and ongoing support if you should need it.

To give your body a chance to get used to Rebif and reduce the impact of side effects, your doctor or MS nurse may suggest you start on a lower dose.

What side effects could I get with Rebif?


Common side effects include:

  • Flu-like symptoms, such as headache, muscle ache and stiffness, chills or fever, following an injection
  • Injection site reactions

You are more likely to have these side effects when you first start taking Rebif. Most people have mild to moderate side effects which tend to go away over time.

A neurologist or MS nurse may suggest ways to reduce these side effects including:

  • To help with flu-like symptoms, it may be helpful to change the time of day of injection in order to sleep through the worst of the side effects
  • To help reduce fever, paracetamol or ibuprofen can be taken before the injection and at four to six hour intervals after the injection, as required

Common side effects (affecting more than 1 person in 100)

  • flu-like symptoms
  • headache
  • injection site reactions
  • blood cell abnormalities
  • feeling weak or tired
  • difficulty sleeping
  • diarrhoea, nausea and vomiting
  • muscular or joint pain
  • depression

Less common side effects (affecting less than 1 person in 100)

  • changes in menstruation (periods)
  • liver abnormalities
  • allergic reactions
  • heart problems and high blood pressure
  • hair thinning or loss
  • damage to small blood vessels leading to kidney problems

A full list of side effects is included in the manufacturer's Patient Information Leaflet (for pre-filled pen).

Assessment before treatment

Before starting Rebif, you should have blood tests to measure blood cell counts and check liver function.

Assessment during treatment

Once you've started treatment, you'll have blood tests to measure blood cell counts and monitor liver function, generally every three months for the first year, then less frequently. Depending on local practice, the tests may be carried out at a local GP surgery or it may be necessary to attend a hospital clinic.

During the coronavirus outbreak, you may find that your regular blood tests happen less frequently, may take place in a different location or may temporarily stop. The Association of British Neurologists has assessed the risks and benefits of blood monitoring for people taking Rebif, and has recommended a safe minimum schedule for all DMDs during this period. The recommendation for Rebif is that the first blood test, 3 months after starting to take the drug, is essential, but that further tests can be halted temporarily. If you notice any new or worsening MS symptoms, you should contact your MS team.

How does Rebif work?

Interferons are proteins that occur naturally in the immune system. It is thought that beta interferon acts by reducing both inflammation and the immune response that is attacking the body's own myelin.

Rebif research

Rebif has been studied extensively since the early 1990s. The following study first demonstrated the effectiveness of Rebif:

  • PRISMS - 1998 - Rebif compared to placebo

This clinical trial compared two doses of Rebif or placebo in 533 people with relapsing remitting MS. Compared with placebo, both doses reduced the relapse rate, by 27% for the lower dose and by 33% for the higher dose over the two year study. Both doses also reduced the severity of any relapses that did occur. Rebif also delayed the progression of disability, and a larger proportion of people were relapse-free with treatment compared to placebo. A separate report on MRI results found that Rebif reduced the number of brain lesions compared to placebo.

  • Risk Sharing Scheme - 2018 - long-term effectiveness of beta interferons and Copaxone

This study was set up in 2002 to evaluate the long-term benefits of beta interferons and Copaxone (glatiramer acetate). More than 5000 people taking either Avonex, Betaferon, Copaxone or Rebif were recruited at study centres around the UK and their disability levels (EDSS) monitored for 10 years. At the end of the study, changes in disability levels were compared to those recorded from an untreated group.

The study found that the DMDs delayed the need to use a walking stick (EDSS 6.0) by four years.

Find out more

National Institute for Health and Care Excellence (NICE).
Beta interferons and glatiramer acetate for treating multiple sclerosis.
NICE technology appraisal guidance TA527
Full guideline (link is external)
Randomised double-blind placebo-controlled study of interferon beta-1a in relapsing/remitting multiple sclerosis. PRISMS (Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis) Study Group.
Lancet 1998;352(9139):1498-504.
Summary (link is external)
Li DK, et al.
Magnetic resonance imaging results of the PRISMS trial: a randomized, double-blind, placebo-controlled study of interferon-beta1a in relapsing-remitting multiple sclerosis.
Annals of Neurology 1999;46(2):197-206.
Summary (link is external)
Palace J, Duddy M, Lawton M, et al.
Assessing the long-term effectiveness of interferon-beta and glatiramer acetate in multiple sclerosis: final 10-year results from the UK multiple sclerosis risk-sharing scheme.
J Neurol Neurosurg Psychiatry. 2019 Mar;90(3):251-260.
Full article (link is external)
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