Rituxan (rituximab) is a prescription drug that’s used to treat rheumatoid arthritis and some kinds of cancer. Rituxan can cause side effects that range from mild to serious. Examples include infusion side effects, infection, and fever.

Specifically, Rituxan is a biologic drug* used to treat the following conditions:

The active ingredient in Rituxan is rituximab. (An active ingredient is what makes a drug work.) The drug comes as an intravenous (IV) infusion (an injection into a vein that’s given over a period of time).

Keep reading to learn about the common, mild, and serious side effects that Rituxan can cause. For a general overview of the drug, including details about its uses, see this article.

* A biologic drug is made from parts of living organisms.

Some people may experience mild or serious side effects during their Rituxan treatment. These can vary depending on what condition the drug is being used to treat.

The following lists include some of the more common side effects reported by adults who took Rituxan in studies. (To read about side effects that are more common in children, see the “Side effects in children” section below.)

More common side effects in adults using Rituxan for non-Hodgkin’s lymphoma include:

In adults using Rituxan for chronic lymphocytic leukemia, more commonly reported side effects include:

More common side effects in people using Rituxan for rheumatoid arthritis include:

In people using Rituxan for granulomatosis with polyangiitis and microscopic polyangiitis, more common side effects include:

  • infections
  • nausea
  • diarrhea
  • headache
  • muscle spasms
  • low level of red blood cells
  • fluid buildup in your hands, legs, or feet
  • infusion side effects*

More common side effects in people using Rituxan for pemphigus vulgaris include:

  • infusion side effects*
  • depression
  • upper respiratory tract infection
  • common cold symptoms, such as sore throat
  • headache
  • infections

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

Rituxan may cause mild side effects in some people. The side effects may vary depending on the condition you’re using Rituxan to treat.

Examples of mild side effects that people using Rituxan have reported include:

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. And do not stop using Rituxan unless your doctor recommends it.

The drug may cause mild side effects other than the ones listed above. For more information, see the Rituxan prescribing information.

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

Serious side effects from Rituxan have been reported, but they aren’t common. Serious side effects that can occur with Rituxan include:

If you develop serious side effects while receiving Rituxan, 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 side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Rituxan, visit MedWatch.

* Rituxan has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effects explained” section below.
† To learn more about this side effect, see the “Side effects explained” section below.
‡ An allergic reaction is possible after using Rituxan. But this side effect wasn’t reported in studies.

Rituxan can be prescribed for use in children age 6 months and older. In children, Rituxan is used with chemotherapy to treat B-cell non-Hodgkin’s lymphoma (NHL) and B-cell acute leukemia (B-AL).

In studies of Rituxan treatment in children, the following side effects were most common:

In addition to the more common side effects listed just above, other side effects were seen in children. These side effects included infusion reactions,* other types of serious infections, and more. Many of the side effects discussed in the rest of this article may be possible in children.

It’s important to note that in rare cases, sepsis due to Rituxan treatment has been fatal. Most of the deaths caused by these reactions happened with the first infusion.

Your child’s doctor can provide more information about possible side effects of Rituxan use in children.

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

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

Hair loss

Hair loss is a possible side effect of Rituxan, especially if you’re using it to treat pemphigus vulgaris (PV).

In one study, people with PV took either Rituxan with prednisone or prednisone by itself. (Prednisone is a steroid medication you take by mouth.) Hair loss occurred in some people who took both drugs but not in anyone who took prednisone by itself.

Hair loss wasn’t reported in studies of Rituxan’s other uses.

What might help

If you’re receiving Rituxan to treat PV, you may not be able to completely prevent hair loss. But the following tips may help manage this side effect:

  • Consider taking a multivitamin supplement with minerals. There’s some evidence that certain vitamins and minerals can help promote hair growth. Examples include iron, selenium, zinc, and vitamins A, B, C, and D. Before you take any new supplements, talk with your doctor or pharmacist.
  • Avoid harsh chemical hair treatments, such as perms or dyes.
  • Because stress may cause hair loss, try adding stress management techniques to your daily routine. Some examples include exercise, aromatherapy, and meditation.

If you’re concerned about hair loss from Rituxan, talk with your doctor. They may recommend changes to your treatment plan.

Infusion side effects

Rituxan has a boxed warning for infusion* reactions. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Infusion reactions from Rituxan are common. They can occur during or within 24 hours after an infusion of the drug.

In rare cases, infusion reactions from Rituxan have been severe, even fatal. Most of the deaths caused by these reactions happened with the first infusion.

Because of this risk, only a healthcare professional can give you Rituxan. They’ll administer your first infusion very slowly and monitor you closely. If you start to develop any infusion reactions, the healthcare professional may stop the treatment or slow it down more.

Infusion-related side effects can range from mild to severe. Symptoms can include:

* You’ll receive Rituxan as an intravenous (IV) infusion (an injection into a vein that’s given over a period of time).

What might help

Your doctor will give you certain medications before each Rituxan infusion, such as methylprednisolone. These medications will lower your risk of a severe infusion reaction.

If you notice any symptoms during or after your infusion, contact your doctor or seek emergency medical care right away. Do not wait to see if the symptoms go away on their own.

Severe skin and mouth reactions

Rituxan has a boxed warning for severe skin and mouth reactions. A boxed warning is the most serious warning from the FDA.

People who receive Rituxan can develop serious reactions on their skin or mucous membranes.* These reactions can be severe or life threatening. Examples include Stevens-Johnson syndrome and toxic epidermal necrolysis.

Symptoms of this side effect may include:

* Mucous membranes are surfaces that line the inside of your mouth and digestive tract. They’re coated with a layer of mucus.

What might help

Although it’s rare, it’s possible to develop a skin or mouth reaction from your first dose of Rituxan.

If you develop any symptoms of a skin or mouth reaction, tell your doctor or get medical help right away. If your reaction is severe, your doctor will likely have you stop using the drug.

Progressive multifocal leukoencephalopathy

Rituxan has a boxed warning for progressive multifocal leukoencephalopathy (PML), a rare disease. A boxed warning is the most serious warning from the FDA.

Rituxan may increase your risk of PML, which is serious and can be life threatening.

In studies of people using Rituxan, some developed PML up to 12 months after their last dose. Symptoms of PML may include:

What might help

If you develop symptoms of PML, tell your doctor or seek medical help right away. Your doctor will likely have you stop using Rituxan.

Reactivation of the hepatitis B virus

Rituxan has a boxed warning for reactivation of existing hepatitis B virus (HBV). A boxed warning is the most serious warning from the FDA.

If you’ve had hepatitis B, using Rituxan may cause the virus to become active again. This is because it remains in your body for a long time, even if you’ve received treatment for hepatitis B.

Reactivation of HBV may cause serious liver damage, liver failure, or, in rare cases, death. HBV reactivation can develop up to 24 months after your last dose of Rituxan.

Symptoms of hepatitis B include:

What might help

Before you start Rituxan treatment, your doctor will test you for HBV. If you have it, they may start you on treatment for hepatitis B before you begin receiving Rituxan.

Be sure to tell your doctor if you develop any symptoms of HBV reactivation. They’ll likely have you stop using Rituxan (if you’re still receiving it) and treat the infection.

Allergic reaction

Like most drugs, Rituxan can cause an allergic reaction in some people. But this side effect wasn’t reported by people using the drug in studies.

Symptoms can be mild or serious and can include:

  • skin 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. To manage your symptoms, they may suggest an over-the-counter antihistamine you take by mouth, such as Benadryl (diphenhydramine). Or they may recommend a product you apply to your skin, such as hydrocortisone cream.

If your doctor confirms that you had a mild allergic reaction to Rituxan, they’ll decide if you should continue using 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 that you had a serious allergic reaction to Rituxan, they may have you switch to a different treatment.

Keeping track of side effects

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

Your side effect notes can include things such as:

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

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

Get answers to some frequently asked questions about Rituxan’s side effects.

How long do side effects of Rituxan typically last?

Most of Rituxan’s more common side effects are temporary, but they can return each time you receive a dose. For example, mild diarrhea may occur after each dose for as long as you receive the drug. How long your Rituxan treatment lasts depends on the condition you have.

Also, Rituxan may stay in your system for 6–12 months after your last dose. Because of this, it can be used as a maintenance (long-term) treatment in certain cases.

For example, if you’re an adult with non-Hodgkin’s lymphoma (NHL), you’ll receive a dose of Rituxan with each chemotherapy treatment for up to 8 doses. If your cancer gets better during this time, you’ll keep using Rituxan as a maintenance treatment after chemotherapy ends.

When Rituxan is used as a maintenance treatment for NHL in adults, you’ll only receive it once every 8 weeks for up to 12 doses. Side effects of Rituxan could happen at any time during and after treatment for as long as the drug remains in your system. In the case of NHL, this could be up to 3 years from when the treatment began.

Does Rituxan cause any long-term side effects?

Less commonly, Rituxan can cause side effects that need to be managed for a long time. Examples include:

If you develop long-term side effects from Rituxan treatment, talk with your doctor. They’ll likely prescribe medications to treat the side effects or suggest ways to manage them. Before starting Rituxan treatment, it’s important to talk with your doctor about any medical problems that you have. They’ll help you decide if the benefits of the drug outweigh the long-term risks.

* Rituxan has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effects explained” section above.

Is weight loss a side effect of Rituxan?

Rituxan doesn’t usually cause weight loss as a side effect. People receiving Rituxan in studies of the drug did not report weight loss.

However, Rituxan can cause diarrhea, nausea, and infections as common side effects. These side effects may lead to weight loss in some people.

If you have any concerns about weight changes since starting Rituxan, talk with your doctor. If you’ve unintentionally lost a lot of weight, they may recommend tests to find out why. They may also suggest ways to help you manage your weight.

Is Rituxan used to treat MS? If so, what are the side effects when it’s used for this condition?

Rituxan isn’t currently approved by the FDA to treat multiple sclerosis (MS). But the drug is sometimes prescribed off-label for this purpose. (“Off-label” means prescribing a drug for a purpose other than what it’s been approved for by the FDA.)

One study suggests that rituximab (the active drug in Rituxan) might be effective for helping to prevent MS symptoms from worsening or flaring up. The side effects of using the drug for MS are thought to be the same as those associated with Rituxan’s approved uses.

This drug comes with several precautions.

Boxed warnings

Rituxan has the following boxed warnings. Boxed warnings are the most serious warnings from the Food and Drug Administration (FDA).

  • Infusion reactions: Infusion side effects can happen during or within 24 hours of a Rituxan infusion. In rare cases, infusion reactions from Rituxan have been severe, even fatal.
  • Severe skin and mouth reactions: These side effects have been reported with Rituxan use. In some cases, they have been fatal.
  • Progressive multifocal leukoencephalopathy: Rituxan may increase your risk of a rare disease called progressive multifocal leukoencephalopathy (PML). In studies of people who received Rituxan, some developed PML up to 12 months after their last dose. PML is serious and can be life threatening.
  • Reactivation of existing hepatitis B virus: If you’ve ever contracted the hepatitis B virus (HBV), Rituxan can cause the virus to become active again. HBV reactivation with Rituxan has been reported to cause liver failure or, rarely, death.

To learn more about these boxed warnings, including symptoms to look for, see the “Side effects explained” section above.

Other warnings

Rituxan 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 receiving Rituxan. The list below includes factors to consider.

Infections or immune system problems: Rituxan often decreases levels of certain white blood cells. These cells are part of the immune system, and they fight off infections. Because the drug reduces white blood cell levels, it can weaken the immune system. If you currently have any infections, tell your doctor before starting Rituxan treatment. And if you already have a weakened immune system or another immune system problem, also tell your doctor. They may suggest other treatment options for you.

Kidney problems: Kidney problems, such as kidney failure, have been reported in people who took Rituxan. Because of this risk, be sure to tell your doctor if you’ve had any kidney problems. They can work with you to help you decide on the best treatment plan for your condition.

Heart problems: Rituxan may increase the risk of heart problems, such as heart attack or atypical heart rhythm. Talk with your doctor about any heart problems you may have had. Because of this risk, you’ll likely be monitored closely during and after all Rituxan infusions. Because of this risk, your doctor will likely monitor you closely during and after all Rituxan infusions.

Lung problems: There have been rare reports of Rituxan causing fatal lung damage. Before starting Rituxan treatment, talk with your doctor about any lung disease or breathing problems you’ve had. They can recommend whether Rituxan is safe for you.

Allergic reaction: If you’ve had an allergic reaction to Rituxan or any of its ingredients, your doctor won’t prescribe Rituxan. Ask your doctor what other medications are better options for you.

Alcohol use and Rituxan

Rituxan does not interact with alcohol.

However, alcohol use can worsen some symptoms of certain medical conditions. If you drink alcohol, talk with your doctor about how much is safe for you to drink with your condition.

Pregnancy and breastfeeding while using Rituxan

It’s not safe to use Rituxan during pregnancy. Doing so can harm a fetus. If you can become pregnant, you should avoid conceiving for at least 12 months after your last dose of Rituxan.

Breastfeeding is not recommended while using Rituxan and for at least 6 months after the last dose. The effects of Rituxan on a child who’s breastfed aren’t known.

If you’re pregnant, breastfeeding, or planning to become pregnant or breastfeed, talk with your doctor. They can help guide you about the safest treatment options during this time.

Rituxan is an effective treatment for certain cancers or autoimmune conditions. If you’re considering Rituxan as a treatment option, it’s helpful to learn about its possible side effects.

If you have questions about your risk of side effects from Rituxan, talk with your doctor. Here are some questions you may want to ask them:

  • What can I do to lower my risk of serious side effects from Rituxan?
  • Is it safe for me to continue my other medications and dietary supplements with Rituxan?
  • Do I have a higher risk of any of Rituxan’s side effects than other people?
  • Are there any vaccines that I should get before starting Rituxan treatment?

To learn more about Rituxan, see these articles:

To get information on different conditions and tips for improving your health, subscribe to any of Healthline’s newsletters. You may also want to check out the online communities at Bezzy. It’s a place where people with certain conditions can find support and connect with others.

Q:

What should I know about tumor lysis syndrome caused by Rituxan? Is it a sign that the drug is working for my condition?

Anonymous

A:

Tumor lysis syndrome can be a sign that Rituxan is killing cancer cells. This syndrome may occur when a large number of cancer cells are broken down very quickly.

However, tumor lysis syndrome can cause serious problems, such as kidney failure or abnormal heart rhythm. So it’s important to know what symptoms it causes. These include nausea, vomiting, diarrhea, and tiredness. If you have any of these symptoms, contact your doctor right away.

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 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.