Your Guide to Ocrevus and Ocrevus Zunovo for Multiple Sclerosis (MS)

Written by Katayoun Sabet, PharmD, Rachel Maynard, PharmD
Medically Reviewed by Courtney Zeigler, BCPS, PharmD on May 19, 2026

Ocrevus (ocrelizumab) and Ocrevus Zunovo (ocrelizumab/hyaluronidase-ocsq) are prescription medicines for multiple sclerosis (MS). Both contain the medicine ocrelizumab, which is a type of monoclonal antibody (B cell therapy). Ocrevus and Ocrevus Zunovo help to slow down MS by aiming at specific cells in the immune system that cause nerve damage. 

The FDA first approved Ocrevus in 2017 to treat adults with relapsing (returning) forms of MS or primary progressive MS. Ocrevus was the first medicine approved for primary progressive MS. In 2026, Ocrevus was approved to treat certain children with relapsing-remitting MS. A health care provider injects it into a vein (intravenous infusion) at a clinic or at home. After the initial dosing, Ocrevus is given twice a year. 

Ocrevus Zunovo was approved in 2024 to treat the same types of MS as Ocrevus in adults. Ocrevus Zunovo is not approved in children. Ocrevus Zunovo is the first medicine approved for adults with relapsing or progressive MS that is given under the skin (subcutaneous) twice a year.

MS happens when your immune system damages the protective covering around the nerves in your brain, called myelin. This affects how your brain communicates with other parts of your body. A group of immune cells called B cells is believed to be the main cause of MS by involving other immune cells, like T cells, causing myelin damage. 

Ocrevus is thought to work by targeting these B cells and making them destroy themselves, though exactly how Ocrevus does this is not fully known yet. Ocrevus Zunovo contains the same medicine as Ocrevus (ocrelizumab) and works the same way to treat MS. However, Ocrevus Zunovo also contains hyaluronidase. Hyaluronidase helps the body absorb the medicine when it is given as an injection under the skin.

Ocrevus or Ocrevus Zunovo may be the right choice for you if you are an adult who:

  • Has a relapsing (returning) form of MS, including clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease, or
  • Has primary progressive MS
  • Does not have a hepatitis B infection

Ocrevus may be the right choice for your child if they: 

  • Have relapsing-remitting multiple sclerosis (RRMS)
  • Are age 10 years and older and weigh at least 55 pounds
  • Do not have a hepatitis B infection

Your health care provider will examine you and review your medical history to decide if Ocrevus or Ocrevus Zunovo is right for you.

Four clinical studies looked at the risks and benefits of Ocrevus for adults with MS. Two studies examined the effects of Ocrevus in adults with relapsing forms of MS, one study was done in adults with primary progressive MS, and another study looked at the side effects from Ocrevus IV infusion (infusion-related reactions).

Two studies, the OPERA 1 and OPERA 2 trials, were done to look at how well Ocrevus worked to treat adults with relapsing MS compared to another MS medicine called interferon beta-1a (Rebif), which is commonly given to treat MS. 

The main question these studies wanted to answer was: How many times per year do each person’s MS symptoms return during the study, in patients who get Ocrevus compared with those who get interferon beta-1a?

Researchers also wanted to compare how many people in the studies had worsening disability from MS lasting at least 12 weeks when they got Ocrevus vs. interferon beta-1a. 

To answer these questions, researchers measured how much MS affected a person's ability to do everyday activities, like walking or moving an arm, and their ability to think. They also did MRI scans of the brain at scheduled times to track the changes in the damaged areas of the brain nerves.

What medicines did the people receive in the studies?

In the OPERA 1 and OPERA 2 trials, half of the people in the studies were randomly selected to get Ocrevus and the other half got interferon beta-1a. Neither the people in the study nor the study health care providers knew who was getting which treatment.

Who was included in the studies?

To take part in the study, people had to:

  • Be between 18 and 55 years old
  • Have MS
  • Have had at least one relapse within the year or two relapses within the 2 years before the study
  • Have no disability or a disability score of 5.5 or lower (out of 10) on a special scale called the Expanded Disability Status Scale

Who was excluded from the studies?

People could not be in the studies if they:

  • Had primary progressive MS
  • Had been given other medicines that affected the B cells or the immune system
  • Had MS with low disability for more than 10 years

What were the study populations?

A total of 1656 people were in the OPERA 1 and OPERA 2 studies. 

  • A total of 827 of them got Ocrevus and 829 got interferon beta-1a.
  • More than half (66%) of them were women.
  • The average age was 37 years.
  • The average time people had MS before the study was about 4 years.
  • The average number of relapses in the year before the study was 1.3.
  • The average disability score was 2.8 (out of 10) on the Expanded Disability Status Scale.
  • About 74% of people had not been given any other medicines besides steroids for MS during the 2 years before the study.
  • No racial breakdowns of people in the studies were provided.

How long were the studies?

People got Ocrevus or interferon beta-1a for almost 2 years (96 weeks) in each study.

One study looked at how well Ocrevus worked in treating people with primary progressive MS.

The main question this study wanted to answer was: How long does it take for people in the study who get Ocrevus to have worsening disability from MS lasting at least 12 weeks, compared to those who do not get it?

To answer this question, researchers measured how much MS affected a person's ability to do everyday activities, like walking or moving an arm, and their ability to think. They also did MRI scans of the brain at scheduled times to track the changes in the damaged areas of the brain nerves.

What medicines did the people receive in the study?

People were randomly selected to get Ocrevus or a placebo. The placebo looked like Ocrevus but did not contain any medicine. 

Who was included in the study?

To take part in the study, people had to:

  • Be between 18 and 55 years old
  • Have primary progressive MS 
  • Have a disability score between 3 and 6.5 (out of 10) on the Expanded Disability Status Scale
  • Have had MS symptoms for less than 15 years if their disability score was higher than 5, or less than 10 years if their disability score was 5 or higher

Who was excluded from the study?

People could not be in the study if they:

  • Had a history of relapsing-remitting, secondary progressive, or progressive relapsing MS
  • Could not have an MRI
  • Had other conditions of the nervous system
  • Had a current infection or a history of a returning infection
  • Had a history of certain cancers
  • Had been given other medicines that affected the B cells or the immune system
  • Had to take steroids or other medicines that affected the immune system for a different condition while in the study

What was the study population?

  • A total of 488 people got Ocrevus, and 244 got a placebo.
  • About half (49%) of the people in the study were women.
  • The average age was 45 years.
  • The average time people had started to have MS symptoms before the study was 6.7 years.
  • The average disability score was 4.7 (out of 10) on the Expanded Disability Status Scale.
  • About 88% of people had not been given any other medicines besides steroids for MS before the study.
  • No racial breakdown of people in the study was provided.

How long was the study?

People got Ocrevus or a placebo for over 2 years (120 weeks).

In addition to the three studies that looked at how effective Ocrevus is, one study, the ENSEMBLE PLUS trial, compared the safety of Ocrevus intravenous (IV) infusion when it was given over a shorter period of 2 hours vs. the usual 3.5 hours.

The main question this study wanted to answer was: How many people in each group have side effects during or within 24 hours after their first Ocrevus infusion?

To answer this question, researchers recorded all side effects that happened during or within 24 hours after the Ocrevus infusion and compared them with people who got the infusion over 2 hours and those who got it over 3.5 hours. 

What was the study population?

  • A total of 586 people were in the study.
  • A total of 291 of them got the injection over 3.5 hours, and 289 got it over 2 hours.

In people with relapsing forms of MS:

  • Ocrevus significantly lowered the number of relapses each year, compared to interferon beta-1a. Those who got Ocrevus had about 46% fewer relapses each year than those who got interferon beta-1a. 
  • More people who got Ocrevus stayed relapse-free during the studies, compared to those who got interferon beta-1a. About 82% of those who got Ocrevus had no relapses, compared to about 71% of those who got interferon beta-1a.
  • Fewer people who got Ocrevus had worsening of disability, compared to those who got interferon beta-1a during the studies. About 9.8% of those who got Ocrevus had their disability worsen, compared to about 15.2% of those who got interferon beta-1a.

In people with primary progressive MS:

  • People who got Ocrevustook significantly longer to show worsening disabilitythat lasted for at least 12 weeks, compared to those who got a placebo. About 32.9% of people who got Ocrevus had their disability worsen, compared to 39.3% of those who got a placebo during the study. This means that Ocrevus lowered the risk of disability by 24%. 

In the infusion side effects study, giving Ocrevus over a shorter period of time did not increase the infusion-relatd side effects. About the same percentage of people (24.4%) who got Ocrevus over 2 hours had side effects during or within 24 hours after their first dose, compared to those who got it over 3.5 hours (23.3%). 

Your results may differ from what was seen in clinical studies.

One clinical study, the OPERETTA 2 trial, looked at the risks and benefits of Ocrevus in children with relapsing-remitting MS (RRMS) who were at least 10 years old and weighed at least 55 pounds. 

The main question this study wanted to answer was: How many times per year do symptoms return during the study in children who get Ocrevus compared with those who get fingolimod (Gilenya)? Prior to this approval, fingolimod was the only FDA-approved treatment for RRMS in children.

In this study, half of the children were randomly selected to get Ocrevus and the other half got fingolimod. Neither the children in the study nor the study health care providers knew who was getting which treatment. 

A total of 93 children got Ocrevus and 94 got fingolimod. The midpoint age of children included in the study was 15 years, the midpoint weight was about 139 pounds, and most (69%) were female. About 66% of children in the study were White, 5% were Black or African American, 5% were multiracial, and 19% had unknown race. Children stayed in the study for at least 24 weeks, although many children in the study received treatment for 72 weeks or longer.

This study found that children who got Ocrevus did no worse than those who took fingolimod in the number of relapses they had each year. Those who got Ocrevus had about 48% fewer relapses each year than those who got fingolimod.

Overall, the safety of Ocrevus in children was similar to adults. The most common side effect was infusion reactions, which happened in about 48% of children, compared to about 24% of children in the fingolimod group (who were given a placebo infusion containing no medicine). Most reactions were mild to moderate, and the reactions became less common and less severe with later doses. Infections were also common and seen in about 73% of children on Ocrevus compared to 59% of those on fingolimod. 

Your child’s results may differ from what was seen in clinical studies.

Ocrevus Zunovo contains the same medicine as Ocrevus, but it is given as an injection under the skin (subcutaneous), while Ocrevus is given as an intravenous infusion. The studies described above for Ocrevus in adults were also used to show that Ocrevus Zunovo is effective for treating relapsing and primary progressive MS.

Another study was done with Ocrevus Zunovo to see if there was any difference in blood levels when the medicine was given under the skin as compared to giving it by intravenous infusion. This study found no meaningful differences in blood levels between Ocrevus Zunovo and Ocrevus. The safety and efficacy of Ocrevus Zunovo was also generally similar to Ocrevus.

Ocrevus or Ocrevus Zunovo may cause serious side effects that you should report to your health care provider right away. Some of these side effects are:

Infusion or injection reaction.A common side effect of Ocrevus is called an infusion reaction, and a common side effect of Ocrevus Zunovo is called an injection reaction. With either of these reactions, it means you might have symptoms during or after receiving your dose, which could be serious and might need hospital care. Your health care provider may give you medicines, such as an antihistamine and a fever-reducing medicine, before your dose to help reduce your risk of these reactions. 

Call your health care provider right away if you have any of these symptoms within 24 hours after an injection, even if they are mild:

  • Coughing or wheezing
  • Dizziness
  • Fatigue
  • Fast heartbeat
  • Feeling faint
  • Fever
  • Headache
  • Hives (raised flat patches on the skin)
  • Itchy skin
  • Nausea
  • Pain, redness, or swelling at the injection site
  • Rash
  • Redness or warmth of your face and neck (flushing)
  • Shortness of breath
  • Swelling of the throat
  • Throat irritation or pain
  • Tiredness
  • Trouble breathing

Risk of cancers, including breast cancer. Ocrevus may increase the risk of cancers. In clinical studies, less than 1% (6 out of 781) of women who got Ocrevus developed breast cancer, while none of the 668 women who got interferon beta-1a or a placebo did. Your health care provider may have you screened for breast cancer, according to guidelines. Let your health care provider know if you feel any lumps in your breast or underarm, or notice any swelling, pain, changes in the size or shape of your breasts, irritation of your breasts, or discharge from your nipples.

Inflammation of a part of the large intestine called the colon (colitis). Let your health care provider know if you have diarrhea that won’t go away in a few days, black stools, blood or mucus in your stool, or severe pain or sensitivity to touch (tenderness) in your stomach area.

Infections. Ocrevus or Ocrevus Zunovo may make your immune system weaker. It may also lower the level of your immunoglobulins (or antibodies), which are substances made by the B cells to help your body fight against infections. Your health care provider will do blood tests to check your blood immunoglobulin levels.

Weakening of the immune system may cause you to get more infections, including infections in your sinuses, throat, airways, or lungs (respiratory tract), skin infections, or herpes infections. 

Avoid being around people who are sick and stay away from crowded places, especially during cold and flu season. Wear a well-fitting mask in busy areas for added safety.

Tell your health care provider if you have any symptoms of a respiratory tract infection, including a fever, chills, or a cough that won’t go away.

Herpes. Tell your health care provider if you have symptoms of a serious herpes infection, including genital sores, pain, or shingles, changes in your eyesight, redness or pain in the eyes, a severe headache that won’t stop, a stiff neck, or if you feel changes in your thinking (confusion).

Hepatitis B infection. If you have had a hepatitis B infection before, it might become active again during or after your treatment with Ocrevus or Ocrevus Zunovo. This can cause serious liver problems. Your health care provider will do blood tests to check if you have ever had hepatitis B before prescribing Ocrevus or Ocrevus Zunovo, and will regularly check you if you are at risk of this during and after your treatment.

Liver damage (hepatotoxicity). Liver damage has happened in some people using Ocrevus or Ocrevus Zunovo, including in people who did not have hepatitis. Your health care provider can do blood tests to check for liver damage. Tell your health care provider right away if you have symptoms of liver damage, such as new or worsening nausea or vomiting, stomach pain, unusual tiredness, or the skin or whites of your eyes turning yellowish in color (jaundice).

Progressive multifocal leukoencephalopathy (PML). Ocrevus or Ocrevus Zunovo has rarely caused a type of brain infection called PML that can cause serious health issues. PML symptoms usually appear slowly and get worse over a few days or weeks and include a hard time thinking, eyesight changes, increasing weakness, and clumsiness.

Let your health care provider know right away if you notice any of these issues or if they don’t go away in a few days.

The common mild side effects of Ocrevus or Ocrevus Zunovo, which usually go away within a few days, are:

Diarrhea. If you have watery or frequent stool without blood, mucus, and severe pain, be sure to drink plenty of fluids. Your pharmacist may recommend nonprescription diarrhea medicines like loperamide.

Respiratory tract infections. If you have a fever, chills, a cough, runny nose, sinus pain, or a headache, drink plenty of fluids and get some rest. Your pharmacist may recommend nonprescription pain medicines like acetaminophen, or cough and cold medicines.

Skin infections or cold sores. Tell your healthcare provider if you think you may have a skin infection, such as if you have a sore, redness, swelling, pus, or a wound that is not healing. Your healthcare provider may adjust your dose of Ocrevus or Ocrevus Zunovo until your infection goes away. Also let your pharmacist know if you think you’re getting a cold sore, for example if you feel a tingling or burning sensation. They may suggest nonprescription cold sore creams to help with the discomfort and speed up healing. Wear a lip balm with sun protection factor (SPF) to help with healing and avoid getting new blisters.

Be sure to let your health care provider know if side effects don’t go away or get worse. 

These are not all the possible side effects of Ocrevus or Ocrevus Zunovo. Contact your health care provider for medical advice about side effects if you are having symptoms that bother you. You can report side effects to the FDA at 800-FDA-1088 (800-332-1088).

Your health care provider will regularly check how well Ocrevus or Ocrevus Zunovo is working for your MS by doing tests on your nervous system (neurological tests) and measuring your disability scores. This includes testing how well you walk, move your arms, and think. They will also look at MRI scan results of your brain. Use Ocrevus exactly as your health care provider tells you. Do not change your dosing schedule or stop using Ocrevus or Ocrevus Zunovo unless your health care provider tells you to.

Tell your pharmacist and other health care providers about all the other prescription and nonprescription medicines, vitamins, supplements, and herbal products you take before starting Ocrevus or Ocrevus Zunovo. Ocrevus or Ocrevus Zunovo may affect other medicines or conditions.

Getting Ocrevus or Ocrevus Zunovo while taking other medicines that affect the immune system, like certain steroids, can make the immune system weaker. Your health care provider will consider this before prescribing Ocrevus or Ocrevus Zunovo for you or switching you from these medicines.

Before getting any vaccine, tell your health care provider that you are on Ocrevus or Ocrevus Zunovo. In clinical studies, Ocrevus made some non-live vaccines – including the tetanus vaccine, pneumonia vaccines, and the flu vaccine – less effective. It is not known how much Ocrevus or Ocrevus Zunovo affects these vaccines. Other examples of non-live vaccines are the hepatitis A vaccine and the polio vaccine.

The effect of Ocrevus or Ocrevus Zunovo on live vaccines has not been studied. Some examples of live vaccines are measles, mumps, rubella, smallpox, chickenpox, and yellow fever vaccines.

You will need a prescription from a health care provider who specializes in the nervous system (a neurologist). Ocrevus or Ocrevus Zunovo is only available at specialty pharmacies, and your health care provider will arrange for you to get it.

If you need assistance paying for Ocrevus or Ocrevus Zunovo, the drugmaker may be able to help you. Check out their Financial Assistance Options tool and Genentech Patient Foundation  at www.ocrevus.com/patient/financial-support/assistance-options.html to learn more about getting help with copay costs and your insurance coverage. You can also contact the drugmaker at 866-4ACCESS (866-422-2377).

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