Avonex (Interferon Beta) is used to treat Multiple Sclerosis (MS). Treatment with Avonex can help to prevent you from getting worse, although it will not cure MS. It can help to reduce the number of relapses that you have and slow down the disabling effects of MS.

Why have I been prescribed Avonex?

  • Avonex (Interferon Beta) is used to treat Multiple Sclerosis (MS). Treatment with Avonex can help to prevent you from getting worse, although it will not cure MS.
  • It can help to reduce the number of relapses that you have and slow down the disabling effects of MS. Your doctor will advise you for how long you can use Avonex or when to stop.

How does it work?

Multiple sclerosis is linked to nerve (brain or spinal cord) damage. In MS, your body’s defence system reacts against it’s own myelin – the ‘insulation’ that surrounds nerve fibres. When myelin is damaged, the messages between the brain and other parts of the body are disrupted. This is what causes the symptoms of MS. Avonex seems to work by stopping your body’s defence system from attacking the myelin.

When and how do I take it?

  • Avonex is injected into a muscle once a week. You will receive training on how to do this. See the leaflet that comes with the injection for instructions on how to inject it.
  • It is not recommended to inject it into the buttocks. A different site should be used each week.
  • Store in the fridge but allow return to room temperature before use.

What’s the dose?

The usual dose for adults and adolescents aged 12 years and over:

  • One injection of Avonex, once a week. Try to use Avonex at the same time on the same day each week.

Could it interact with other tablets?

If you are using any other medicines, especially those used to treat epilepsy or depression, tell your doctor or pharmacist as Avonex may affect other medicines or be affected by them. This includes any other medicines including medicines obtained without a prescription. Herbal products should also only be taken after talking with your doctor.

What are the possible risks or side-effects?

Like all medicines, Avonex can cause side effects, although not everybody gets them.

Serious side effects: 

Serious allergic reactions
If you get any of these:

  • swelling of the face, lips or tongue
  • difficulty breathing
  • a rash.

Call a doctor immediately. Do not use any more Avonex until you have spoken to a doctor.


If you get any symptoms of depression:

  • feeling unusually sad, anxious or worthless.

Call a doctor immediately.

Liver problems:

If you get any of these symptoms:

  • yellowing of your skin or the whites of your eyes (jaundice)
  • itching all over
  • feeling sick, being sick (nausea and vomiting)
  • easy bruising of the skin.

Call a doctor immediately as they may be signs of a possible liver problem.

Very common side effects:

Common side effects:

  • loss of appetite
  • feeling weak and tired
  • difficulty sleeping
  • depression
  • flushing
  • runny nose
  • diarrhoea (loose stools)
  • feeling or being sick (nausea or vomiting)
  • numbness or tingling of skin
  • rash, bruising of the skin
  • increased sweating, night sweats
  • pain in your muscles, joints, arms, legs or neck
  • muscle cramps, stiffness in the joints and muscles
  • pain, bruising and redness at the injection site
  • changes to blood tests. Symptoms you might notice are tiredness, repeated infection, unexplained bruising or bleeding.

Can I drink alcohol while taking it?

There are no known interactions between alcohol and Avonex.
Always ask you doctor or pharmacist however as other medications you are taking may have a bearing on this.

What if I’m pregnant/breastfeeding?

If you are pregnant do not start using Avonex.

  • If you could get pregnant, you need to use contraception while you use Avonex.
  • If you are planning a baby or if you become pregnant while you are using Avonex, tell your doctor. You and your doctor can discuss if you should carry on with treatment.
  • If you are already pregnant, or think that you might be, talk to a doctor as soon as you can.
  • If you want to breastfeed talk to your doctor first.

If you have any more questions please ask your Pharmacist.

Remember to keep all medicines out of reach of children
Please Note: We have made every effort to ensure that the content of this information sheet is correct at time of publish, but remember that information about drugs may change. This sheet does not list all the uses and side-effects associated with this drug. For full details please see the drug information leaflet which comes with your medicine. Your doctor will assess your medical circumstances and draw your attention to any information or side-effects which may be relevant in your particular case.










Health Reference: Multiple sclerosis