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How to Prescribe Interferon Beta-1a: Rebif®

James Bowen, MD

Medical Director, Multiple Sclerosis Center

Swedish Neuroscience Institute

Seattle, WA



  • Slows the course of multiple sclerosis when used regularly over long periods of time.
  • Does not improve existing symptoms.
  • Is not used to treat acute MS attacks.


Generic name: interferon beta-1a


How supplied: RebifÒ comes in prepackaged kits containing all needed supplies. It comes in prefilled syringes. Two doses are available: 22 mcg/syringe, and 44 mcg/syringe. There are 12 syringes per pack. A titration pack for use during the first month is available.


Initial dose: RebifÒ is administered subcutaneously three times each week. Initially, the dose should be tapered upwards. A titration pack is available for use during this first month titration.


Maintenance dose: 44mcg subcutaneously three times per week. 22mcg subcutaneously three times per week is an alternative dose used in some patients.


Antipyretics: Antipyretics should be prescribed for every patient starting RebifÒ. Flu-like side effects usually begin about an hour after the injection, so the antipyretics can be administered at the time of the injection. Typical medications include: acetaminophen 650mg qid, aspirin 650mg qid, ibuprofen 600mg tid, or naproxen 250mg bid. In cases with refractory flu-like side effects, acetaminophen can be combined with either aspirin, ibuprofen, or naproxen. Flu-like side effects may also be decreased with pentoxifylline 400mg tid, or with prednisone 20mg po given with each injection. Antipyretics may be needed only at the time of the injection or they may also be needed the following day. Over time, antipyretics may be tapered or discontinued as tolerated.


Sharps container: Sharps containers for needle disposal should be prescribed.


Autoinjector: Autoinjectors are available through the pharmacy.


Initial training: Initial training for patients is provided by the manufacturer (EMD Serono and Pfizer) through visiting nurse services. This may be arranged by contacting MS Pathways at 1-877-447-3243. Larger centers may perform their own training.


Laboratory testing: Basic chemistry panels, transaminases, and CBCs should be monitored. These should be checked before initiating treatment, and at 1, 3, and 6 months after starting treatment. After 6 months they should be checked periodically. Thyroid function tests are recommended every 6 months for those with thyroid dysfunction.


Most common side effects:

  • Flu-like side effects (fever, myalgias) should be treated with antipyretics (see above). Flu-like side effects typically lessen over the first few months of use.
  • Injection site reactions consist of inflammation and edema. Injection site reactions resolve over several weeks. They often decrease with continued use. They may be minimized by assuring that the injections are deep enough in the subcutaneous tissues. Icing the injection site may help. Lidocaine creams known by brand names, such as EmlaÒ or ElamaxÒ, may decrease injection site pain as well as cutaneous reactions. Hydrocortisone cream may decrease the inflammation.
  • Injection site necrosis may rarely develop at sites of severe injection site reaction.
  • Depression. Whether RebifÒ causes depression is uncertain. Patients should be monitored and treated appropriately should depression develop.
  • Transaminase elevation may occasionally occur. Elevations up to three times normal may be followed. Elevations above three times normal should be treated with dose reduction. Once transaminases have improved the dose can be gradually increased.
  • Mild leucopenia may be followed. Severe leucopenia usually responds to dose reduction.


Company Support:   MS Lifelines - 1-877-447-3243, 


Last Updated: November 2009