Beta interferons

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• Who can take beta interferons (Avonex, Plegridy or Rebif)?
• How do beta interferons (Avonex, Plegridy or Rebif) work?
• How well do beta interferons (Avonex, Plegridy or Rebif) work?
• Beta interferons (Avonex, Plegridy or Rebif) side effects
• Stopping beta interferons (Avonex, Plegridy or Rebif)
• What tests do you need with beta interferons (Avonex, Plegridy or Rebif)?
• Beta interferons (Avonex, Plegridy or Rebif) and pregnancy, breastfeeding and contraception

Who can take beta interferons (Avonex, Plegridy or Rebif)?

You can take beta interferons if you have active relapsing MS. ‘Active’ MS means you have relapses and/or MRI scans show that you have new, active or growing lesions.

How do beta interferons (Avonex, Plegridy or Rebif) work?

Your body makes its own interferons (a protein) to dampen down inflammation. These drugs are man-made versions. They can reduce (and might prevent) the inflammation that damages nerves in MS.

You inject beta interferons at home. When you start a nurse or doctor will show you the best way to inject. Instructions also come with the drug. 

Depending on the type of beta interferon, you inject under your skin or into a muscle. You don’t inject into a vein. You inject using a pre-filled syringe. Or you might use an injecting device or ‘pen’ which you put against your skin and click. With this you don’t see the needle going in. 

How often you inject, and where, depends on the type of beta interferon. You inject:

• Avonex into muscle once a week
• Plegridy under the skin or into muscle every two weeks
• Rebif under the skin three times a week

You keep these drugs in the fridge (at 2°C to 8°C). If you need to, you can keep Avonex at room temperature for a week, Rebif for two weeks and Plegridy for up to a month. Keep them in their packaging and away from sunlight. Full storage details are in the leaflet that comes with the drug.

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How well do beta interferons (Avonex, Plegridy or Rebif) work?

The effectiveness of beta interferons (Avonex, Plegridy and Rebif) is classed as 'moderate'. Each DMT can be rated as ‘moderate’, ‘good’ or ‘high’ based on two things. One is how much it reduces relapses. The other is how much it slows down how disability getting worse.

Relapses dropped by: 33 to 36%

In trials on average, people saw a drop their number of relapses drop by around a third. This was compared to people who took a placebo. This is a dummy treatment with no drug in it.

Disability getting worse was slowed down by: a modest amount

In trials, on average, people saw a modest drop in the risk of their disability getting worse. This was compared to people who took a placebo.

These results come from two studies. One was the 1999 PRISMS study. This followed 533 people over two years, half took the beta interferon, half got a placebo. It also showed people on beta interferon got fewer brain lesions. 

The other was a 2014 trial of over 1,500 people called ADVANCE. For the first year half took the beta interferon Plegridy. The other half took a placebo but switched to Plegridy in the second year. After the first year on beta interferon people saw their relapses drop by 36%. Their risk of their disability getting worse fell by 38%. They also had fewer brain lesions. 

How well do beta interferons (Avonex, Plegridy or Rebif) work over many years?

Evidence from people on beta interferons for years shows their effect is much bigger than ‘modest’. That’s if you start one early on in your MS.

A UK study known as the MS Risk Sharing Scheme looked at 5,000 people who took beta interferons (or glatiramer acetate) for ten years. The study found that these treatments had a positive effect. They delayed the need for a walking stick by four years on average.

A study followed nearly 6,000 people in Canada and France who took beat interferons for many years. It found that people taking beta interferons lived longer than people who didn't take it.

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Beta interferons (Avonex, Plegridy or Rebif) side effects

Compared to other DMTs the risk of side effects, especially serious ones, is among the lowest.

Very common side effects (more than 1 in 10 people get them)

• flu-like symptoms (headache, muscle aches, chills, fever)
• headaches

Common side effects (up to 1 in 10 people get them)

• bruising, redness or pain where you inject
• loss of appetite
• feeling weak and tired
• difficulty sleeping
• depression
• flushing (going red in the face)
• upset stomach
• numb or tingling skin
• stiffness or pain in muscles or joints
• rash or bruising of the skin
• sweating or night sweats

After a beta interferon injection at least one in 10 people feel like they have flu. They get headaches, muscle aches, chills or a fever. These usually last for no longer than two days (48 hours) after each injection. These symptoms often get better the longer you use the drug. Ibuprofen or paracetamol can help, as can injecting before going to bed.  

Your skin can become red, hard, bruised or itchy where you inject. 

Beta interferons might cause depression. You might not be given one if you’ve had depression in the past.

Find out more about all the possible side effects of the beta interferons:

Read more about the Avonex side effects

Read more about the Plegridy side effects

Read more about the Rebif side effects

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Stopping beta interferons (Avonex, Plegridy or Rebif)

You should never stop taking a DMT without telling your neurologist. You’ll need to stop taking your beta interferon if you develop ‘neutralising antibodies’ to it (see below).

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What tests do you need with beta interferons (Avonex, Plegridy or Rebif)?

Your neurologist might want you to have an MRI scan once a year to see if the drug is working. But how often you have scans depends on what your neurologist thinks you need. If your MS seems stable, you might have scans less often. 

Regular blood tests will check that your blood and liver are OK. You may have tests on your kidneys and thyroid. You might have your blood pressure checked. If you have a heart condition, this will be monitored when you start the drug. 

Blood tests will also check if you’ve developed ‘neutralising antibodies’. Your immune system makes antibodies to kill viruses and bacteria. But some people find their body makes ‘neutralising antibodies’ against beta interferons. Over time these can stop beta interferons working. If regular blood tests show this has happened, you can switch to a new DMT.

The chance of developing these antibodies depends on the drug. It happens to 5-8% of people on Avonex, 13-24% on Rebif but less than 1% on Plegridy.

You don’t need any special vaccinations before you start this drug. You can have vaccinations while on it. That includes an annual flu jab. Your MS team or GP can answer any questions about vaccinations.

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Beta interferons (Avonex, Plegridy or Rebif) and pregnancy, breastfeeding and contraception

Pregnancy

Guidelines say you can take beta interferons (Rebif, Plegridy and Avonex) while pregnant if your neurologist thinks you need to. 

You might decide to stop taking your interferon a month before you try to get pregnant. One month (or less) is the ‘washout period’ for beta interferons. That’s how long it takes for the drug to leave your body. But your neurologist might say there’s no need for a wash out period with these drugs. 

Women who’ve just had a baby can be more likely to have a relapse. So if you decide to stop this drug to get pregnant, your MS team will advise you about when to go back on it after the birth.

If you want to have a child, discuss this with your neurologist or MS nurse. If you think you’ve become pregnant, let your medical team know at once. Never stop your DMT without first getting their advice.

Breastfeeding

Guidelines say you can breastfeed while taking a beta interferon (Avonex, Plegridy or Rebif). The benefits of breastfeeding for the baby while their mother is on these drugs are bigger than any risk.

Contraception

There are no special recommendations about contraception while taking beta interferons (Avonex, Plegridy or Rebif). They don’t interfere with how contraception works. And you don’t need to use contraception while you take these drugs.

Read more about pregnancy, breastfeeding and contraception and DMTs

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