Rituximab (Rituxan®)

OncoLink Team
Last Modified: January 11, 2016

Pronounced: ri-TUX-i-mab

Classification: Monoclonal Antibody

About Rituximab

Rituximab is a synthetic (man made) antibody directed against a protein called CD20, found on the surface of normal and cancerous B-cells, which are part of the immune system. An antibody is a part of the immune system that "marks" things (such as germs, bacteria and, in this case, cancer cells) to be destroyed by the immune system. Once rituximab attaches itself to the B cells expressing CD20, it summons the body's immune system to attack and destroy those cells.

How to Take Rituximab

Rituximab is given by intravenous (IV, into a vein) infusion. It may take several hours or longer to receive your first dose of rituximab. Depending on how you tolerate the medication, you may receive subsequent doses more quickly. The dosage and schedule is determined by the person's body size, type of cancer, and treatment regimen.

You should not receive rituximab if you have an active infection or receive a vaccine containing a live virus while on therapy (including oral polio, smallpox, MMR, nasal flu, and chickenpox vaccines).

Possible Side Effects of Rituximab

There are a number of things you can do to manage the side effects of rituximab. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:

Infusion and Allergic Reactions

Allergic or infusion reactions may occur during the treatment, typically within 30 minutes to 2 hours of beginning the first infusion. This is less common after the first treatment. You will be given an antihistamine such as diphenhydramine and acetaminophen (Tylenol®) before your treatment to reduce the chance of a reaction.

During the infusion, if you experience difficulty breathing or swallowing, experience chest pain, cough or wheezing, swelling of lips or face, develop itching, rash or hives, lightheadedness, fever, chills, or shakes inform your nurse immediately. Additional medications may be given to alleviate your discomfort. Your infusion may be slowed or temporarily stopped.

Infection and Low White Blood Cell Count (Neutropenia)

This medication can cause life threatening infections, with or without a decrease in white blood cell counts. White blood cells (WBC) are important for fighting infection. While receiving treatment, your WBC count can drop, putting you at a higher risk of getting an infection. You should let your doctor or nurse know right away if you have a fever (temperature greater than 100.4), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal.

Tips to preventing infection:

  • Washing hands, both yours and your visitors, is the best way to prevent the spread of infection.
  • Avoid large crowds and people who are sick (i.e.: those who have a cold, fever or cough or live with someone with these symptoms).
  • When working in your yard, wear protective clothing including long pants and gloves.
  • Do not handle pet waste.
  • Keep all cuts or scratches clean.
  • Shower or bath daily and perform frequent mouth care.
  • Do not cut cuticles or ingrown nails. You may wear nail polish, but not fake nails.
  • Ask your doctor or nurse before scheduling dental appointments or procedures.
  • Ask your doctor or nurse before you, or someone you live with, has any vaccinations.

Low Red Blood Cell Count (Anemia)

Your red blood cells are responsible for carrying oxygen to the tissues in your body. When the red cell count is low, you may feel tired or weak. You should let your doctor or nurse know if you experience any shortness of breath, difficulty breathing or pain in your chest. If the count gets too low, you may receive a blood transfusion.

Low Platelet Count (Thrombocytopenia)

Platelets help your blood clot, so when the count is low you are at a higher risk of bleeding. Let your doctor or nurse know if you have any excess bruising or bleeding, including nose bleeds, bleeding gums or blood in your urine or stool. If the platelet count becomes too low, you may receive a transfusion of platelets.

  • Do not use a razor (an electric razor is fine).
  • Avoid contact sports and activities that can result in injury or bleeding.
  • Do not take aspirin (salicylic acid), non-steroidal, anti-inflammatory medications (NSAIDs) such as Motrin®, Aleve®, Advil®, etc. as these can all increase the risk of bleeding. Unless your healthcare team tells you otherwise, you may take acetaminophen (Tylenol).
  • Do not floss or use toothpicks and use a soft-bristle toothbrush to brush your teeth.


Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help.  Talk to your healthcare team for helpful tips on dealing with this side effect.

Flu-Like Symptoms

You may experience flu-like symptoms, including muscle and body aches, headache, fever and chills. Acetaminophen may help relieve these symptoms. However, fever can be a sign of an infection and should be reported to your healthcare provider.

GI Obstruction or Tear

This medication can cause a bowel obstruction (blockage) or a tear in the intestinal wall, also called a gastrointestinal perforation. Signs of this can include: severe constipation, new or worsening pain in the abdomen, new abdominal swelling, chills, fever, constipation, nausea or vomiting.  If you experience any of these, contact your healthcare provider immediately or go to the emergency room.

Hepatitis B Reactivation

This medication can also cause Hepatitis B reactivation in patients who have previously had hepatitis.  Be sure your healthcare provider is aware of previous Hepatitis B diagnosis and treatment. Your will also be tested for the Hepatitis B virus prior to beginning treatment with this medication.

Tumor Lysis Syndrome

If there is a large amount of tumor cells in your body prior to treatment, you are at risk for tumor lysis syndrome. This happens when the tumor cells die too quickly and their waste overwhelms the body. You may be given a medication (allopurinol) and IV fluids to help prevent this. If you experience nausea, vomiting, diarrhea or become lethargic (drowsy, sluggish), notify your oncology team right away.


Progressive Multifocal Leukoencephalopathy (PML) is a rare but very serious brain infection that has been reported with this medication. The signs of PML may develop over several weeks or months. They may include changes in mood or usual behavior, confusion, thinking problems, loss of memory, changes in vision, speech, or walking, and decreased strength or weakness on one side of the body. If you develop any of these signs, notify your healthcare provider immediately.

Other Side Effects

  • Rituximab can cause chest pain or irregular heart beats. Notify your healthcare provider if you develop cardiac symptoms.
  • Your provider will monitor your kidney function with blood work. Let your provider know if you have little or no urine output.
  • Severe skin and mouth reactions have been reported. Notify your healthcare provider if you develop painful sores or blisters, on your skin, lips or inside your mouth, rash or peeling skin.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment and for at least 12 months after treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should consult with your healthcare team before breastfeeding while receiving this medication.

Frequently Asked Questions