Rebif® (interferon beta-1a)


The active ingredient of Rebif® is interferon beta-1a. Interferons are proteins produced naturally in the human body to help fight infections and regulate the immune system. Some beta interferons have been shown to slow down activity and disease progression in MS. They do this by helping regulate the immune system, reducing attacks on myelin.

In clinical trials Rebif® significantly decreased the frequency of MS relapses and slowed down the accrual of disability.

Rebif® is taken three times a week by subcutaneous (under the skin) injection. You will receive a month’s supply which consists of twelve injections.

You can choose from four different delivery devices for Rebif®:

  1. RebiSmart® – an electronic auto-injection device with multi-dose cartridge
  2. RebiSlide® – a manual auto-injector with multi-dose cartridge
  3. RebiDose® – a pre-filled, single use disposable auto-injection device
  4. RebiJect® – a pre-filled syringe with auto injection device

The slight differences in the delivery devices allows for customisation to the method which will suit you, and your lifestyle, best. For assistance and training on how to use the delivery devices please contact Merck Medical Information on 1800 073 243 Monday to Friday between the hours of 9.00am to 5.00pm or speak with your MS Nurse.

Rebif® helps most people with MS, but may have side effects in some people. All medications have side effects. It is important to notify your health professional if you experience any side effects or are feeling unwell.

The most common side effects of Rebif® are flu-like symptoms including fever, chills, and muscular pain, headache or fatigue, itching or rash, abdominal pain, diarrhea or nausea, muscle pain or aches, back pain or painful joints, muscle stiffness or spasms, weakness, difficulty walking and increased sweating. You may also experience injection site reactions including redness, swelling, bruising and pain.

Your neurologist will assist you to assess the risks and the expected benefit of treatment with Rebif® prior to starting therapy and over the course of treatment. Your health professional can provide comprehensive information on the use of Rebif®, including precautions and side effects.

Rebif® is suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects.

If you are currently pregnant or trying to become pregnant, please discuss your individual circumstances and treatment options with your neurologist or healthcare team.

The levels of conventional interferon beta-1a in breastmilk are minuscule. In addition, because interferon is poorly absorbed orally, it is not likely to reach the bloodstream of the infant.

If you are currently breastfeeding, please discuss your individual circumstances and treatment options with your neurologist or healthcare team.

Rebif® is currently used for the treatment of Australians living with relapsing forms of multiple sclerosis (MS), including clinically isolated syndrome, relapsing-remitting disease and active secondary progressive disease.  

From 1 December 2022, REBIF will no longer be available on the Pharmaceutical Benefits Scheme (PBS) for Australians living with MS. This includes all available presentations of REBIF, including the interferon beta-1a single dose autoinjector, single dose pre-filled syringe and multidose cartridge. 

The removal of REBIF from the PBS means people with MS will no longer be able to start treatment with this product, from 1 December 2022. 

However, for people with MS who are currently being treated with REBIF, it is important to note that while the therapy will be removed from the PBS from 1 December 2022, REBIF scripts will still be filled until 1 April 2023. Your neurologist will need to obtain an authority to prescribe the medication for you. 

Further information about the PBS, your entitlements and details regarding the PBS safety net (which protects patients and their families requiring a large number of PBS items) is available through the Medicare Australia website at:  

Rebif® (interferon beta-1a)

Forms of MS used for:
Relapsing forms of MS, Clinically Isolated Syndrome at risk of MS (specific criteria)
Administration route:
Subcutaneous injection (injection under skin)
Dosage and frequency:
Three times per week
Refrigerate 2-8°C
TGA approval date:
January 2000
Available on PBS:
Available until 1 December 2022. People with MS who are currently taking REBIF® (interferon beta-1a) and wish to continue with this therapy as long as possible, are strongly advised to request a new script from their GP or treating specialist as soon as possible before 1 December 2022 to ensure they can continue to access PBS-listed REBIF until the last date of drug dispensing on 31 March 2023.

General Information and Assistance

Most pharmacies do not keep Rebif® in stock. It is therefore important to let your pharmacist know a few days before you need the medication so that they can order it in for you.

Rebif® should be stored at 2-8°C in the original packing to protect it from light. Should refrigeration be temporarily unavailable, Rebif can be stored at 25°C for up to 14 days, then put back in the refrigerator and used before the expiry date.

Merck has a toll free Medical Information and Customer Service line: 1800 073 243 Monday to Friday between the hours of 9.00am to 5.00pm.

For more information

Speak to your neurologist about what treatment best suits your individual circumstances.

MS Nurses can also provide information, training and ongoing support in managing your immunotherapy.

MS Australia does not recommend any specific disease-modifying treatment for people living with MS. Decisions about any treatments, taking into consideration the potential benefits and side effects for each individual’s circumstances, should be made in careful consultation with the person’s neurologist.

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Rebif®(Interferon beta-1a)