Introduction

This information is for people who have multiple sclerosis. It tells you about interferon beta, a treatment used to reduce relapses and disability in multiple sclerosis. It is based on the best and most up-to-date research.

Does it work?

Yes, injections of interferon beta may help people with relapsing-remitting MS. But we don't know if it can help people with secondary progressive MS. (For details on different types, see Types of multiple sclerosis.)

Interferon beta injections don't work for everyone, so doctors follow guidelines about who should have them on the NHS. (For more, see When to start treatment.)

What is it?

Interferons are proteins that your body makes to fight infections and to calm inflammation. They can also be made in a laboratory and used as medicines. There are two types of interferon beta:

• interferon beta-1a (brand names Avonex, Rebif)

• interferon beta-1b (brand names Betaferon, Extavia).

These drugs are all similar, but you use them in slightly different ways:^[30]

• Avonex is injected into your muscle once a week

• Betaferon and Extavia are injected under your skin every other day

• Rebif is injected under your skin, usually three times a week.

How can it help?

Interferon beta injections can help you in several ways.

• If you have relapsing-remitting MS, having injections of interferon beta can reduce how many relapses you have. In the studies, 55 in 100 people taking interferon had attacks of symptoms over two years. This compared with 69 in 100 people taking a dummy treatment (a placebo).^[31]

• Interferon beta may slow the progression of your MS and reduce your level of disability.^[31]

The first long-term study of interferon beta showed that the amount of disability people had 16 years later was about the same, whether they had interferon or a pretend (placebo) treatment. But people who took interferon beta in the original trial lived longer. We don't know for sure that this was because of the treatment.^[32]

The research isn't clear on whether interferon beta helps people with progressive MS. Some studies found a benefit, but others didn't.^{[33][34][35][36][37]} (If you have relapsing-remitting MS, you have bouts of symptoms that come and go. If you have progressive MS, some of your symptoms stay after a relapse and get worse over time.)

Some research has looked at people who've only had one attack of symptoms.^[38][39] Taking interferon beta seems to make it less likely that people will get more symptoms of MS within a year.^[38] In one of the studies, 2 in 10 people taking interferon beta went on to have more symptoms of MS, compared with 3 in 10 people who took a placebo.

However, you're not likely to be offered interferon beta if you've only had one attack of symptoms. That's because most people are not diagnosed with MS until they have had at least two attacks. Doctors need to make certain that there aren't other causes for your symptoms.