Ocrevus (ocrelizumab) is a prescription drug that’s used to treat multiple sclerosis and clinically isolated syndrome. Ocrevus can cause side effects that range from mild to serious. Examples include infections and infusion reactions.

Some people may experience mild or serious side effects during their Ocrevus treatment. Examples of the more commonly reported side effects of Ocrevus include:

Other side effects are also possible with Ocrevus. Read on to learn more.

* To learn more about this side effect, see “Side effects explained” below.
† This side effect was reported only in studies of people with primary progressive multiple sclerosis (MS). It’s not clear whether this side effect was reported in people with relapsing-remitting MS.

Examples of mild side effects that have been reported in people who took Ocrevus to treat multiple sclerosis (MS) or clinically isolated syndrome include:

Other mild side effects were reported in people with primary progressive MS:

These mild side effects were reported in people with relapsing forms of MS:

In most cases, these side effects should be temporary. Some may be easily managed, too. But if you have any symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop treatment with Ocrevus unless your doctor recommends it.

Ocrevus may cause mild side effects other than the ones listed above. See the Ocrevus prescribing information for more information.

* To learn more about this side effect, see “Side effects explained” below.
† Herpes infections only occur in people who’ve been exposed to the herpes virus.

Serious side effects that have been reported with Ocrevus include:

If you develop serious side effects while receiving Ocrevus, call your doctor right away. If the side effects seem life threatening or if you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Ocrevus, visit MedWatch.

* To learn more about this side effect, see “Side effects explained” below.
† Herpes and hepatitis B infections only occur in people who’ve been exposed to the herpes virus.
‡ An allergic reaction is possible after using Ocrevus. But it’s not clear whether this side effect occurred in studies.

Below you can find answers to some frequently asked questions about Ocrevus’s side effects.

Could I experience weight gain during my Ocrevus treatment?

It’s not likely. In studies, weight gain wasn’t reported in people who received Ocrevus for multiple sclerosis (MS).

Some people who received Ocrevus for primary progressive MS reported swelling in their arms or legs. Swelling can sometimes cause weight gain. If you have swelling with Ocrevus, talk with your doctor. They may prescribe medication to help ease this side effect.

Some people with MS gain weight if their symptoms make it harder to exercise or move around as usual. But there could also be many other reasons for gaining weight.

Talk with your doctor if you experience unwanted weight gain while having Ocrevus treatment. They can help you figure out what might be causing the weight gain and how to manage it.

Does Ocrevus cause hair loss?

It’s not known whether Ocrevus causes this side effect. In studies of the drug, hair loss wasn’t reported.

Hair loss can be a side effect of certain other medications used to treat MS. But there could also be other reasons for this problem. Talk with your doctor if you have hair loss during Ocrevus treatment. They can help you figure out the possible cause and how to manage it.

Are there any long-term side effects of Ocrevus?

Ocrevus works by reducing some of your immune system activity (sometimes referred to as “weakening” your immune system). As a result, Ocrevus can increase your risk of infections. You’ll have an increased risk of infections as long as you continue to have Ocrevus treatment. This side effect may last for longer than a year after stopping treatment.

You should take extra care to avoid infections during and after treatment with Ocrevus. To read more about this, see the “Side effects explained” section below.

How long do side effects from Ocrevus typically last?

Most side effects of Ocrevus tend to go away on their own within a few days or a couple of weeks. But if you get an infection or infusion reaction, it may sometimes need treatment with medication. To read more about this, see the “Side effects explained” section below.

Talk with your doctor or pharmacist if you have symptoms of an infection or infusion reaction while receiving Ocrevus. Also talk with them if you have any side effects that last longer than a few days or are severe.

Does Ocrevus cause any eye-related side effects?

It’s unlikely. Eye-related side effects weren’t reported in studies of people who received Ocrevus.

But herpes infections have been reported in people undergoing treatment with Ocrevus, and these infections can sometimes affect the eyes. (Herpes infections only occur in people who’ve been exposed to the herpes virus.) Herpes eye infections have been reported with Ocrevus since this drug has been on the market. These infections are rare.

See your doctor right away if you have symptoms of a herpes eye infection while receiving Ocrevus. These may include eye pain or redness, as well as changes in vision.

If you have a herpes eye infection during Ocrevus treatment, your doctor will likely prescribe antiviral medication to treat it. They may also delay your next dose of Ocrevus until the infection has cleared up.

Can joint pain occur from using Ocrevus?

Ocrevus is not known to cause this side effect. In studies, joint pain wasn’t reported in people who received Ocrevus. But some people with relapsing forms of MS had back, leg, or arm pain with Ocrevus treatment.

While Ocrevus and MS don’t specifically affect your joints, MS can sometimes cause symptoms that lead to joint pain. For example, weakened muscles, stiff or painful limbs, and balance problems can affect your joints.

If you have joint pain while using Ocrevus, talk with your doctor. They can help you figure out the possible cause and suggest ways to manage it.

Here’s more detail about some of the side effects Ocrevus may cause.

Fatigue

Ocrevus isn’t known to cause fatigue (lack of energy), except as part of an infusion reaction. To learn more about this, see “Infusion reactions” below.

Fatigue is one of the most common symptoms of multiple sclerosis (MS).

What might help

If you have fatigue, it’s important to get plenty of rest. Talk with your doctor about ways to manage MS-related fatigue.

Increased risk of cancer

Ocrevus reduces some of your immune system activity (sometimes referred to as “weakening” the immune system). As with other medications that work this way, Ocrevus may slightly increase your risk of developing cancer. In studies, cancers such as breast cancer, though rare, were reported in people receiving Ocrevus.

Symptoms of breast cancer may include:

What might help

For certain types of cancer, such as breast cancer, taking part in screening programs may help identify any growths or tumors early. For example, current guidelines recommend that females who are ages 45 years and older have a mammogram (breast X-ray) to check for breast cancer every 1 or 2 years. Talk with your doctor about your risk of developing cancer and any screening programs you should take part in.

If you have any unusual lumps, bumps, pains, or other unexplained symptoms, be sure to tell your doctor right away.

Here are some general tips to help minimize your risk for cancer:

  • Avoid smoking.
  • Maintain a weight that’s healthy for you.
  • Eat a healthy diet that contains plenty of fresh fruits and vegetables.
  • Protect your skin from sunburn.
  • Follow your doctor’s instructions for taking part in cancer screening programs.

Talk with your doctor or pharmacist if you’re concerned about any possible increased risk of cancer with Ocrevus.

Diarrhea

Some people using Ocrevus may experience diarrhea. In studies, diarrhea was a fairly common side effect reported by people receiving Ocrevus for primary progressive MS.

What might help

If you have diarrhea, be sure to drink plenty of fluids to avoid getting dehydrated. Sports drinks or rehydration solutions, such as Pedialyte, can help replace lost fluids and electrolytes. If diarrhea is troublesome, you can also try over-the-counter medications such as Imodium (loperamide). But check with your doctor or pharmacist first to make sure these medications are suitable for you.

Talk with your doctor if you have diarrhea that’s severe, doesn’t go away in 2–3 days, or contains blood. Severe or bloody diarrhea can be a symptom of a serious condition in some cases, such as colitis (inflammation of the colon). Your doctor can examine you for other possible symptoms.

Infections, such as respiratory or skin infections

Ocrevus reduces some of your immune system activity. As a result, it can increase your risk for infections. For example, you may have an increased risk for herpes infection (if you’ve been exposed to the herpes virus).

In studies, infections were commonly reported in people using Ocrevus. Types of infections reported in people treated with Ocrevus include:

  • Upper respiratory infections, such as colds or sinusitis. Symptoms may include:
    • sinus pain
    • sneezing
    • runny nose
    • stuffy or blocked nose
  • Lower respiratory infections, such as bronchitis, pneumonia, or the flu. Symptoms may include:
    • fever
    • chills
    • cough
    • sore throat
  • Herpes infections, such as cold sores, shingles, or genital herpes. Symptoms may include:
    • tingling, itching, or burning sensation around your mouth
    • small, painful, fluid-filled sores on your lips, cheeks, chin, or the inside of your nostrils
    • small, painful, fluid-filled sores on or around your genitals
    • skin pain, itchiness, or rash
    • flu-like symptoms, such as fever or sore throat
  • Skin infections, such as cellulitis. Symptoms may include:
    • redness or discoloration
    • swelling
    • warmth
    • tenderness or pain
    • blisters or spots

Most infections reported in studies, including herpes infections, were mild to moderate in severity.

But in rare cases, infections can be severe. Since Ocrevus has been on the market, serious cases of herpes infections have been reported in some people receiving this treatment. These include widespread skin or soft tissue infections, as well as herpes infections of the eyes or brain.

What might help

Here are a few tips that may help prevent you from getting an infection:

  • Wash your hands or use hand sanitizer frequently, especially if you’ve been in a public place.
  • Avoid crowds when possible.
  • Stay away from people who are sick.
  • Don’t share face cloths, towels, lip balms, or lipsticks with others.
  • Avoid kissing or sexual contact with someone who has an active herpes infection.
  • Eat a healthy diet that contains plenty of fruit and vegetables.
  • Make sure you’re up to date with immunizations before you start Ocrevus treatment.

If you have symptoms of an infection during Ocrevus treatment, talk with your doctor or pharmacist. They can advise you on whether the infection may be treated with over-the-counter medications or home remedies. Or you might need prescribed medication, such as antibiotics or antivirals, to treat an infection.

See your doctor right away if you have an infection that starts to get worse or doesn’t get better after about a week. You should also see your doctor right away if you have symptoms of a more serious herpes infection. These may include:

If you have an active infection, you should not start Ocrevus treatment or have another dose until the infection has cleared up.

Infusion reactions

Some people may have a reaction to Ocrevus infusion. Infusion reactions were one of the most common side effects reported in studies of Ocrevus. These reactions typically happen during or just after the infusion. But they can sometimes happen up to 24 hours later.

You’re more likely to have a reaction with your first infusion than with later infusions. Infusion reactions are usually mild, but they can become serious and need urgent treatment.

Symptoms of an infusion reaction include:

What might help

A healthcare professional will monitor you closely during your infusion and for at least 1 hour afterward. If you have a reaction during this time, they may slow the infusion down or stop it until your symptoms get better. Depending on how severe your symptoms are, you may need medication to treat the reaction.

You should tell your doctor right away about any infusion reaction symptoms you develop in the 24 hours after your infusion.

If you have an infusion reaction, you’ll likely be given medications before your next dose to help prevent the reaction from happening again. This is called premedication. Medications you may have include Tylenol (acetaminophen), a corticosteroid such as Medrol (methylprednisolone), and an antihistamine such as Benadryl (diphenhydramine).

If you have a severe infusion reaction, your doctor may recommend that you stop treatment with Ocrevus.

Allergic reaction

Like most drugs, Ocrevus can cause an allergic reaction in some people. But it’s not clear whether this side effect occurred in studies.

Symptoms can be mild or serious and can include:

  • rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest an over-the-counter antihistamine you take by mouth, such as Benadryl (diphenhydramine), or a product you apply to your skin, such as hydrocortisone cream, to manage your symptoms.

If your doctor confirms you had a mild allergic reaction to Ocrevus, they’ll decide whether you should continue receiving it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you had a serious allergic reaction to Ocrevus, they may have you switch to a different treatment.

Keeping track of side effects

During your Ocrevus treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of drug you were receiving when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help your doctor learn more about how the drug affects you. Your doctor can use this information to adjust your treatment plan if needed.

Ocrevus may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you start Ocrevus treatment. Factors to consider include those in the list below.

Current infections: Ocrevus can reduce some of your immune system activity and make it harder for your body to fight infections. If you have an active infection, you should not start Ocrevus until the infection has cleared up. Your doctor may prescribe medication to treat the infection. If you have a history of infections that keep coming back, tell your doctor. Your doctor will determine whether Ocrevus is right for you.

Hepatitis B: Before you start Ocrevus treatment, your doctor will test you for the hepatitis B virus. If you have an active hepatitis B infection, you should not receive Ocrevus until it has been treated. And if you’ve had hepatitis B in the past, Ocrevus treatment could make it flare up again. You may need extra monitoring while you use this drug.

Vaccinations: Ocrevus reduces your immune system activity and can affect how your body responds to vaccines. Non-live vaccines may be less effective during Ocrevus treatment, and live vaccines could cause serious infections. (A live vaccine contains a weakened form of the virus or bacteria the vaccine is designed to protect you from.)

Before you start Ocrevus treatment, talk with your doctor about your immunization history. They may recommend getting certain vaccines first. This can help protect you from infections.

You should not start Ocrevus treatment until at least 2 weeks after receiving non-live vaccines and at least 4 weeks after receiving live vaccines. Examples of live vaccines include:

You should not have live vaccines during or after stopping Ocrevus treatment until your immune system has recovered. This could take at least a year.

Allergic reaction: If you’ve had an allergic reaction to Ocrevus or any of its ingredients, you should not receive Ocrevus. Ask your doctor which other medications are better options for you.

Alcohol use and Ocrevus

Alcohol isn’t known to interact with Ocrevus.

As with all medications, if you drink alcohol, talk with your doctor about how much is safe to drink during Ocrevus treatment.

Pregnancy and breastfeeding while using Ocrevus

It’s not known whether Ocrevus is safe to use if you’re pregnant. When used by pregnant people, medications similar to Ocrevus have led to reduced immune system activity in some newborn infants.

If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options. They’ll likely recommend a treatment other than Ocrevus.

It’s not known whether Ocrevus is safe to use while breastfeeding. It’s also not known whether the medication passes into breast milk or if it can affect a child who’s breastfed. If you’re breastfeeding or plan to breastfeed, talk with your doctor about whether Ocrevus is right for you.

If you have questions about the side effects of Ocrevus, talk with your doctor or pharmacist. Examples of questions you might want to ask include:

  • How do side effects from Ocrevus compare with side effects from other MS treatments?
  • If I have an infusion reaction, will I need to stay in a hospital?
  • Are there any vaccinations I should receive before starting Ocrevus? Are there vaccines I can’t get during treatment?
  • Does Ocrevus raise my risk of getting COVID-19? Can I receive the COVID-19 vaccine during my treatment?

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Q:

Can I use Ocrevus with other MS medications? If so, will this increase my risk of side effects?

Anonymous

A:

In general, you should not take Ocrevus with other MS medications.

Corticosteroids, such as Medrol (methylprednisolone), are a possible exception. These drugs are used as premedication before an infusion of Ocrevus. Premedications may help prevent or reduce the severity of infusion reactions by reducing your immune system response.

Corticosteroids have been used to treat acute episodes (flare-ups) of MS. But they aren’t meant for long-term treatment of MS.

Using Ocrevus with other MS medications will increase your risk for side effects, especially serious infections. This is because these medications will reduce your immune system activity, just as Ocrevus does. If you’re currently taking other MS medications, talk with your doctor before starting or switching to Ocrevus.

The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.