Introduction

This information is for people who have multiple sclerosis. It tells you about natalizumab, 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. Natalizumab may help you if you have the relapsing-remitting type of multiple sclerosis (MS). (To learn more, see Types of multiple sclerosis.)

Taking natalizumab can reduce the number of relapses you have and make it less likely that you'll become disabled. However, the benefits need to be weighed against the side effects, which can be serious.

What is it?

Natalizumab is a drug that affects how your immune system works. It's given as a drip (also called an intravenous infusion or IV). This will probably take about an hour. You'll need one dose each month.

The brand name for natalizumab is Tysabri.

The National Institute for Health and Clinical Excellence (NICE) is the organisation that gives advice on which treatments should be available on the NHS. NICE says that natalizumab is only recommended for severe, relapsing-remitting MS that is getting worse quickly. That means:^[66]

• You have two or more serious relapses in a year

• An MRI scan of your brain shows nerve damage that's getting worse.

How can it help?

If you have the type of MS where your symptoms come and go (relapsing-remitting MS), natalizumab can slow down how quickly your MS gets worse. It can also cut the number of relapses you get.

In one study, about 7 in 10 people who took natalizumab went for two years without having a relapse.^[67] Only about 4 in 10 people who took a dummy treatment (a placebo) went for two years without a relapse.

People who took natalizumab were also less likely to become more disabled than people who took a placebo.

How does it work?

Natalizumab affects white blood cells, which are part of your immune system. It stops these cells passing from your blood into your brain and nervous system.^[68] This may help stop the damage to your nerves that causes the symptoms of MS.

Can it be harmful?

Natalizumab can cause serious side effects. In studies, about 1 in 1,000 people taking natalizumab got a dangerous infection in their brain.^[69] This type of infection is bad enough to kill someone or leave them severely disabled. Its medical name is progressive multifocal leucoencephalopathy (PML).

But this infection is very rare. As of January 2010, only 31 people worldwide had this infection from taking natalizumab, out of about 66,000 who'd taken natalizumab. It seems more likely after you've been taking the drug for more than two years.^[70]

Natalizumab may also cause damage to your liver. Your doctor should do blood tests to check that your liver is working properly. See your doctor straight away if you notice that your skin or the whites of your eyes become yellowish, or if your urine looks darker than normal.^[71]