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Key points about ocrelizumab

  • Ocrelizumab is used to treat multiple sclerosis.
  • Ocrelizumab is also called Ocrevus.
  • Find out how it is given and possible side effects.
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Ocrelizumab is used to treat relapsing-remitting and primary progressive multiple sclerosis (MS).

MS is caused by your immune system mistakenly attacking the myelin sheath in your brain and spinal cord. It is thought that specific types of B cells and T cells in your body are involved in the attack. Ocrelizumab sticks to the B cells and helps kill them. This 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.

Ocrelizumab is given in hospital by slow injection into a vein in your arm (called intravenous infusion). The infusion usually takes 2 to 3.5 hours. You’ll be monitored for side effects for an hour after the infusion.

  • You get the first dose as 2 separate infusions, 2 weeks apart.
  • After that you have an infusion once every 5 to 6 months.

During the infusion

Ocrelizumab 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. You will be monitored 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. These are usually more common on your first infusion. Your doctor or nurse may slow down the infusion or stop it until these symptoms go away. You will also be given medicines (eg, paracetamol and an antihistamine) shortly before the infusion to help control this reaction. 

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

  • Reaction during the infusion: Ocrelizumab may cause an infusion-related reaction for up to 24 hours after you've received a dose. It’s important that you tell your doctor or go to the Accident and Emergency at your nearest hospital if you notice any unusual symptoms. See side effects below.
  • Increased risk of infections: Ocrelizumab 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.
  • Pregnancy: You should avoid becoming pregnant while you are having ocrelizumab and for at least 6 months after your last dose. Talk to your healthcare provider about which types of contraception are suitable for you and your partner. Tell your healthcare provider if you become pregnant while using ocrelizumab.
  • Vaccines: Some vaccines shouldn't be taken if you are on ocrelizumab. Always check with your doctor or pharmacist first. It's safe for you to have the annual flu vaccine.
  • Other medicines: Ocrelizumab may interact with a few medicines and herbal supplements, so check with your doctor or pharmacist before starting ocrelizumab or before starting any new medicines, including those you may buy over-the-counter.

Like all medicines, ocrelizumab 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?
  • Itchy, red or inflamed skin or a rash
  • Mouth or throat irritation or pain, throat swelling or trouble breathing
  • Flushing, high fever
  • Headache
  • Fatigue, dizziness, nausea or a fast heart-rate.
  • You may experience these symptoms during the infusion or any time up to 24 hours after the infusion.
  • Before the infusion you will be prescribed medicine to reduce these effects.
  • If these side effects occur, tell your doctor immediately or phone Healthline on 0800 611 116.
  • Signs of an infections such as fever, cough, sore throat, diarrhoea (runny poo) or generally feeling weak and unwell
  • Tell your doctor immediately or phone Healthline on 0800 611 116.
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 ocrelizumab.


  1. Ocrelizumab(external link) NZ Formulary, NZ

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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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