Rituxan Side Effects


The CD20 targeted monoclonal antibody rituximab (marketed as Rituxan) is FDA approved for several indications, most notably non-Hodgkin's lymphomas of B-cell origin. It is very effective at killing a patient's B-cells, but it does so without discriminating between healthy B-cells and cancerous B-cells. Depleting the B-cell population in a patient, while very good in eliminating the cancer, also causes some side effects, some of which are potentially fatal. What follows is an incomplete list of the more common side effects.

Frequently Reported Side Effects in Rituxan

The frequently reported side effects listed here might occur shortly after infusion or a couple of months after infusion; whatever the case, they should be reported to one's doctor:

  • Low back pain, blood in urine, or painful urination
  • Muscle contraction, weakness, tightness
  • Breathing issues or rapid/slow heart rate
  • Confusion, dizziness, weakness on one side
  • Chest pain, nausea, sweating
  • Fever, chills, body aches and other flu symptoms
  • Ease of bruising
  • Earache, mouth ulcers, skin sores
  • Skin rashes
  • Severe constipation
  • Night sweats


Depleting the body of B-cells is depleting it of much of its immune system response to foreign pathogens, so patients on Rituxan are considered to be immunosuppressed. They are therefore at risk of developing infections that they might otherwise not develop.

Infusion Reactions

Reactions during infusion are not common, but when they occur they can be extremely serious. Reactions are signaled by symptoms such as:

  • Urticaria
  • Hypotension
  • Angioedema
  • Hypoxia
  • Pulmonary infiltrates
  • Acute respiratory distress syndrome
  • Bronchospasm
  • Bronchospasm

Pre-treatment that includes an antihistamine or acetaminophen can often stop this allergic reaction before it ever starts.

Tumor Lysis Syndrome

The deaths of many, many B-cells in a short period of time can flood the bloodstream with the contents of those cells and lead to what's known as Tumor Lysis Syndrome (TLS). In Rituxan this is potentially toxic and potentially fatal.

Other Adverse Reactions

Some of the other, very rare potential adverse reactions that have been reported with Rituxan include:

  • Hepatitis B Reactivation
  • Developing a fatal brain virus known as Progressive Multifocal Leukoencephalopathy (PML)
  • Mucocutaneous reactions
  • Cardiac arrhythmia
  • Renal toxicity
  • bowel obstruction and perforation

All side effects should be reported to one's doctor or health care professional, regardless of severity.

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