Rituxan (rituximab) is a prescription brand-name medication. It’s approved by the Food and Drug Administration (FDA) to treat many different conditions in certain situations:

Rituxan may be used short term or long term, depending on the condition it’s treating. For a general overview of Rituxan, including details about its uses, see this article.

Here are some fast facts about Rituxan:

  • Active ingredient: rituximab, which is a biologic
  • Drug class: monoclonal antibody
  • Drug form: solution given as an IV infusion by a healthcare professional

Like other drugs, Rituxan infusions can cause side effects (also called adverse effects). These can include reactions to the infusion itself, which are known as infusion reactions.*

Read on to learn about potential common, mild, and serious side effects of Rituxan.

* Rituxan has a boxed warning for this side effect. This is a serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section below.

Rituxan can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who received Rituxan in clinical trials. These side effects can vary depending on which condition the drug is being used to treat.

More common side effects in people who received Rituxan for rheumatoid arthritis included:

More common side effects in people who received Rituxan for chronic lymphocytic leukemia included:

More common side effects in people who received Rituxan for non-Hodgkin lymphoma included:

More common side effects in people who received Rituxan for pemphigus vulgaris included:

  • mild depression
  • upper respiratory infection, such as the common cold
  • infusion reaction*
  • headache

More common side effects in people who received Rituxan for granulomatosis with polyangiitis or microscopic polyangiitis included:

* Rituxan has a boxed warning for this side effect. This is a serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section below.
† To learn more about this side effect, see the “Side effect specifics” section below.

Mild side effects can occur with Rituxan use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Rituxan’s prescribing information.

Mild side effects that have been reported with Rituxan include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while receiving Rituxan and want to tell the FDA about it, visit MedWatch.

* To learn more about this side effect, see the “Side effect specifics” section below.

Rituxan may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Rituxan’s prescribing information.

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

Serious side effects that have been reported and their symptoms include:

* Rituxan has a boxed warning for this side effect. This is a serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section below.
† To learn more about this side effect, see the “Side effect specifics” section below.

Learn more about some of the possible side effects of Rituxan.

Boxed warnings

Rituxan comes with four boxed warnings. A boxed warning is a serious warning from the FDA. It alerts doctors and patients about potentially serious side effects.

Severe reactions of the skin or mucous membranes. Rituxan may cause severe reactions affecting your skin or mucous membranes, but this is rare. (An example of a mucous membrane is the lining of your mouth.) These reactions can occur at any time while you’re being treated with Rituxan.

Examples of severe skin and mucous membrane reactions with Rituxan include Stevens-Johnson syndrome and toxic epidermal necrolysis. These reactions can, in extreme cases, be fatal.

Symptoms of severe skin and mouth reactions with Rituxan can include:

Progressive multifocal leukoencephalopathy. Treatment with Rituxan can result in a rare but serious brain infection called progressive multifocal leukoencephalopathy (PML). There’s no known treatment or cure for PML, and it can, in some cases, be fatal. The risk of PML continues for up to 12 months after your last dose of Rituxan.

Symptoms of PML can include:

  • confusion
  • dizziness
  • loss of balance
  • problems talking or walking
  • weakness on one side of your body
  • vision problems

Infusion reactions. Rituxan is given as an IV infusion by a healthcare professional. It’s possible you’ll have infusion reactions, which are side effects that occur during or after an infusion. Infusion reactions can occur up to 24 hours after a Rituxan infusion.

In Rituxan’s clinical trials, the reactions were most common within 30 to 120 minutes after the first Rituxan infusion. The risk of infusion reactions is lower after the first infusion.

Mild infusion reactions were among the most common side effects caused by Rituxan in the clinical trials. Serious infusion reactions were rare.

Symptoms of a mild Rituxan infusion reaction can include:

  • cough and wheezing
  • hives or skin rash
  • dizziness or fainting
  • itching
  • hypotension (low blood pressure)
  • swelling of the mouth, tongue, or throat, which can make it hard to breathe

In extremely rare cases, infusion reactions to Rituxan can be severe. These severe reactions can include heart attack, ventricular fibrillation (irregular, weak heart rate), and, in certain cases, death.

Hepatitis B reactivation. If you’ve had an infection called hepatitis B, the virus that caused it may still be in your body. Rituxan treatment could reactivate the virus (make the virus active again). Hepatitis B reactivation can cause serious liver problems, including liver failure. In extreme cases, it can cause death.

Symptoms of hepatitis B reactivation can include:

  • tiredness that gets worse over time
  • jaundice

If the virus reactivates, your doctor will likely have you stop receiving Rituxan. They’ll also treat the virus.

What you can do

Talk with your doctor right away if you experience any symptoms of the boxed warnings listed above. Your doctor will likely have you stop receiving Rituxan.

To lower your risk of infusion reactions, your doctor may give you medications before each infusion. Also, they’ll test you for hepatitis B before and during Rituxan treatment and for up to 24 months after your last dose.

Hair loss

Hair loss is a possible side effect of Rituxan use, but it isn’t likely to occur. This side effect was reported in clinical trials only by people who received Rituxan for pemphigus vulgaris (PV). In this trial, hair loss was among the more common side effects. People who received Rituxan for other conditions in other trials didn’t report hair loss.

Keep in mind that hair loss has been reported as an unusual but possible symptom of PV.

What you can do

Talk with your doctor if you have hair loss that bothers you while you’re treated with Rituxan. They may suggest a treatment for this side effect.

Weight gain

It’s possible to have weight gain as a side effect of Rituxan use, but this isn’t likely to occur. This side effect was reported only by people who received Rituxan for non-Hodgkin lymphoma (NHL). And it was common in only one clinical trial of people who received Rituxan for NHL.

Keep in mind that weight gain can be linked to some of the conditions Rituxan is used to treat, such as rheumatoid arthritis (RA). People with RA often have trouble exercising regularly due to RA symptoms such as joint pain and fatigue. This can lead to weight gain.

What you can do

If you have any changes in your weight or are concerned about your weight during your Rituxan treatment, talk with your doctor. They may order tests to determine the cause of the weight change. They may also recommend ways to help you maintain a moderate weight.

Headache

Headache is a potential side effect of Rituxan treatment. This was a common side effect in the drug’s clinical trials regardless of which condition people received Rituxan for.

Headache can also be a symptom of a more serious side effect of Rituxan, including infusion reactions* and serious infections, such as shingles.

* Rituxan has a boxed warning about this side effect. This is a serious warning from the FDA. To learn more, see “Boxed warnings” above.

What you can do

If you develop a headache that bothers you or won’t go away, talk with your doctor. They can examine you to see if your headache is a symptom of a more serious side effect. If it’s not, your doctor may suggest nondrug treatments such as a cold compress or relaxation techniques. They may also recommend taking an over-the-counter pain reliever, such as Tylenol (acetaminophen) or Advil (ibuprofen).

Allergic reaction

As with most drugs, Rituxan can cause an allergic reaction in some people.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, talk with your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep receiving Rituxan. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Rituxan may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Does Rituxan cause any long-term side effects?

Treatment with Rituxan may cause long-term side effects. These can include side effects that occur even after treatment ends, such as:

Rituxan can also cause side effects that last for a long time or don’t go away, even if you stop receiving the medication. These can include:

To see symptoms of these side effects, refer to the “Serious side effects” and “Side effects specifics” sections above. Your doctor or pharmacist can offer more information about long-term side effects from Rituxan, including possible treatments.

* Rituxan has a boxed warning for this side effect. This is a serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section above.

Is weight loss a side effect of Rituxan?

No, weight loss isn’t a known side effect of Rituxan. Weight loss wasn’t reported by people who received the drug in clinical trials.

Weight loss can be a symptom of some of the conditions Rituxan is used to treat, including chronic lymphocytic leukemia and non-Hodgkin lymphoma.

If you have any changes in your weight or are concerned about your weight during your Rituxan treatment, talk with your doctor. They may order tests for you to determine the cause of the weight change. They may also recommend ways to help you maintain a moderate weight.

Will I have side effects if I stop treatment with Rituxan?

It isn’t likely that you’ll have side effects from stopping Rituxan treatment.

With some drugs, certain side effects occur after treatment ends. These side effects are known as withdrawal effects. Withdrawal effects weren’t reported by people treated with Rituxan in clinical trials.

Keep in mind that symptoms of your condition may come back if you stop receiving Rituxan. However, these aren’t withdrawal effects.

It’s important that you do not stop receiving Rituxan unless you first speak with your doctor. If you both agree that stopping the treatment is right for you, they can recommend other drugs for your condition. This may help prevent your symptoms from returning.

There are important precautions to consider before starting Rituxan treatment, including several boxed warnings about serious side effects.

Boxed warnings

Rituxan has boxed warnings about the following:

Boxed warnings are serious warnings from the Food and Drug Administration (FDA). For details about these warnings, see “Boxed warnings” in the “Side effect specifics” section above.

Other precautions

Be sure to talk with your doctor about your health history before you receive Rituxan. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Heart problems. In rare cases, treatment with Rituxan can cause heart-related side effects that may be serious. These include heart attack and arrhythmia. If you already have a heart problem, your risk of these side effects may increase. Your doctor can help determine if Rituxan is safe for you with your heart problem.

Kidney problems. In rare cases, Rituxan treatment can cause kidney-related side effects, including kidney failure. If you have a kidney problem, such as chronic kidney disease, your risk of these side effects may increase. Your doctor can help determine if Rituxan is right for you with your kidney problem.

Lung problems. Lung-related side effects are rare with Rituxan, but they can occur. These side effects may include upper and lower respiratory tract infections and acute respiratory distress syndrome. Lung-related side effects can also occur as infusion reactions* to Rituxan.

If you have an existing lung problem, you may have an increased risk of lung-related side effects with Rituxan treatment. An example of a lung problem is chronic obstructive pulmonary disease (COPD). Your doctor can help determine if Rituxan is safe for you.

Severe viral infection. If you’ve had a severe viral infection, the virus that caused it may still be in your body. Rituxan treatment could make the virus become active again. Examples of these infections include chickenpox, shingles, and hepatitis B.*

Before you begin receiving Rituxan, your doctor will test you for the hepatitis B virus. If you have the virus, they’ll likely want to treat it before prescribing the drug to you. They’ll also monitor you for new or reactivated viral infections while you’re treated with Rituxan.

Allergic reaction. If you’ve had an allergic reaction to Rituxan or any of its ingredients, your doctor will likely not prescribe Rituxan. Ask them what other medications may be better options for you.

* Rituxan has a boxed warning about this side effect. This is a serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section above.

Alcohol use with Rituxan

There are no known interactions between drinking alcohol and treatment with Rituxan.

However, alcohol may interact with medications that are used in combination with Rituxan, such as methotrexate (Trexall). Also, alcohol could worsen certain side effects of Rituxan, such as headache, weight gain, nausea, and diarrhea.

If you drink alcohol, talk with your doctor about how much is safe to consume while you receive Rituxan.

Pregnancy and breastfeeding while receiving Rituxan

Here’s some information about pregnancy, breastfeeding, and Rituxan.

Pregnancy. Your doctor will likely recommend that you do not receive Rituxan while you’re pregnant. The drug may cause harm to a developing fetus. If you can become pregnant, your doctor should order a pregnancy test for you before prescribing the drug. This is to confirm you’re not pregnant.

You should use an effective form of birth control during your Rituxan treatment and for at least 12 months after your last dose. If you become pregnant or think you’re pregnant during your treatment, talk with your doctor right away.

Breastfeeding. It is not recommended to breastfeed during your Rituxan treatment and for at least 6 months after your last dose. The drug may pass into human breast milk. And it isn’t known if Rituxan can cause serious side effects in a child who is breastfed. Talk with your doctor about safe feeding options for your child during your Rituxan treatment.

Like most medications, Rituxan can cause side effects. Most are mild and usually go away on their own after a few days or weeks. However, the drug can cause long-lasting side effects in rare cases.

Rituxan has boxed warnings for infusion reactions and hepatitis B reactivation. It also has boxed warnings for progressive multifocal leukoencephalopathy and severe reactions of the skin or mucous membranes. Boxed warnings are serious warnings from the FDA. For details on these warnings, see the “Side effect specifics” section above.

If you become pregnant during your Rituxan treatment, talk with your doctor right away.

If you’d like to learn more about Rituxan, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information about Rituxan. For details about other aspects of Rituxan, refer to this article.
  • A look at cancer and rheumatoid arthritis. For details about some of the conditions Rituxan is used to treat, see our cancer hub and arthritis hub. These lists of articles about lymphoma, leukemia, and rheumatology may be helpful, too.

Disclaimer: Medical News Today 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 another 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.