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How long does an Ocrevus infusion take?

Medically reviewed by Carmen Pope, BPharm. Last updated on Dec 12, 2022.

Official answer


The first two times you have Ocrevus, the infusion will take at least 2.5 hours. If you develop a reaction to Ocrevus during your infusion, the infusion rate will be slowed down and the infusion will take longer.

Your whole infusion appointment will take around 5 to 6 hours, because there is a pre-infusion check-up, during which you will receive medications that reduce infusion reactions, and you will need to wait for at least an hour post-infusion so your health care team can monitor you for any side effects or infusion reactions.

The third and subsequent infusions may be infused over 2 hours for those people who did not experience any serious infusion reactions (IRs) with the first two doses. If you have experienced a serious reaction previously, Ocrevus will be infused over at least 3.5 hours, depending on how you tolerate it.

Ocrevus (ocrelizumab) is a treatment for multiple sclerosis (MS) that works by targeting a specific protein, called CD20 that exists on the surface of immature and mature B-lymphocytes.

Ocrevus is given by intravenous infusion (slowly, directly into a vein) once every six months (twice a year). The first dose of Ocrevus will be split into two infusions. On your first day of treatment, you will receive 300mg of Ocrevus diluted into an infusion bag containing 0.9% sodium chloride and given directly into a vein over at least 2.5 hours. This is followed two weeks later by a second 300mg infusion, again given over at least 2.5 hours.

Six months later, you will receive your next dose. This will be given as a single 600mg infusion which will be infused over at least 2 hours provided you haven't experienced any serious infusion reactions in the past.

Why does my Ocrevus infusion appointment take so long?

Before each infusion, you will have a pre-infusion check-up. This allows your health care team to:

  • Check for any signs of active infection
  • Check your vital signs (which includes your heart rate, blood pressure, temperature, and respiratory rate
  • Administer medications to reduce your risk of an infusion reaction, which will include a corticosteroid 30 minutes before the infusion, an antihistamine 30 to 60 minutes before the infusion, and possibly a fever-reducing medication.

This will take around 30 to 60 minutes.

After your pre-infusion check-up, it will time for your infusion. You will be seated in a comfortable chair along with your reading materials, snacks, and music. An IV infusion needle will be placed in your arm and connected to an infusion pump. The infusion will last at least 2.5 hours but may last longer if you develop an infusion reaction and your health care team needs to slow or stop your infusion.

After your infusion has finished, you will need to stay at the infusion center for at least an hour so that your health care team can monitor you for any side effects or post-infusion reactions. You are at risk of infusion reactions for up to 24 hours following your infusion. Contact your health care provider if you develop any signs or symptoms of an infusion reaction which may include:

  • A rash, hives, or itchy skin
  • Coughing, wheezing, or difficulty breathing
  • Dizziness, tiredness, or feeling faint
  • A fast heartbeat
  • Fever or flushing
  • Headache
  • Nausea
  • Throat swelling, tightness, irritation, or pain.

An infusion reaction is MOST likely to occur during your first dose of Ocrevus.

Your complete Ocrevus infusion appointment will take 5 to 6 hours.


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