Key points about natalizumab

  • Natalizumab is used to treat multiple sclerosis.
  • Natalizumab is also called Tysabri.
  • Find out how it's given and the possible side effects.
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Natalizumab is used to treat relapsing remitting multiple sclerosis (MS). Natalizumab belongs to a group of medicines called disease-modifying therapies which help to slow or reduce the worsening of disability in people with relapsing remitting MS.

  • MS is caused by your immune system mistakenly attacking the myelin sheath in your brain and spinal cord.
  • It's thought that specific types of B cells and T cells in your body are involved in the attack.
  • Natalizumab sticks to the T cells and stops them getting into your brain and spinal cord where they would attack the myelin covering around your nerves.
  • This stops inflammation and damage to the nerve, reduces the chance of a flare-up and slows the progression of your disease.

Read more about multiple sclerosis.

Natalizumab is given in hospital by slow injection into a vein in your arm (called intravenous infusion). It's given once every 4 weeks. The infusion usually takes about 1 hour. You’ll be monitored for side effects for an hour after the infusion has finished.

During the infusion

Natalizumab can cause a reaction while it's being given so you’ll be carefully monitored during the infusion and for at least 1 hour afterwards. This is to see if you have trouble breathing, or experience fever, chills, flushing, skin rash, itching, dizziness or headache. Tell the nurse immediately if any of these symptoms occur. 

Here are some things to know when you're taking natalizumab. Other things may be important as well, so ask your healthcare provider what you should know about.

  • Increased risk of infections: Natalizumab weakens your body’s defence (immune) system, so you're more likely to pick up infections. It's important to avoid anyone who has chickenpox or shingles.
  • Vaccines: Some vaccines shouldn't be taken if you are on natalizumab. Always check with your doctor or pharmacist first. It's safe for you to have the annual flu vaccine.
  • Your memory or balance: if you or your whānau notice problems with your memory, vision or balance, contact your doctor.
  • Other medicines: Natalizumab may interact with a few medicines and herbal supplements, so check with your doctor or pharmacist before starting natalizumab or before starting any new medicines, including those you may buy over-the-counter.

Like all medicines, natalizumab can cause side effects, although not everyone gets them. Often side effects improve as your body adjusts to the new medicine.

Side effects What should I do?
  • Joint pain
  • Tiredness
  • A runny or blocked nose
  • Mild headache or dizziness
  • These are quite common when you first start natalizumab and should settle with time.
    Tell your doctor if they bother you.
  • Signs of an infections, eg, fever, cough, sore throat, diarrhoea (runny poo) or generally feeling weak and unwell
  • Tell your doctor immediately or phone Healthline on 0800 611 116.
  • Signs of problems with your liver, eg, severe tummy pain, yellowing of the eyes and skin, dark urine
  • Tell your doctor immediately or phone Healthline on 0800 611 116.
  • Signs of progressive multifocal leukoencephalopathy (PML), eg, loss of coordination, clumsiness
    loss of language ability (aphasia), memory loss, vision problems

  • PML is a viral infection in the brain. It's a rare but serious side effect. 
  • You'll get blood tests that look for the virus that causes it.
  • If you're at risk of PML you'll be checked for early signs of it. 
  • Tell your doctor immediately.
Did you know that you can report a medicine side effect to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product.(external link)

The following links provide further information about natalizumab. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Tysabri(external link) Medsafe consumer medicine information, NZ
Tysabri (Natalizumab)(external link) Multiple Sclerosis New Zealand
Natalizumab (Tysabri)(external link) MS Society, UK


  1. Natalizumab(external link) New Zealand Formulary

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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