Rituximab

Antineoplastic monoclonal antibodies
Antineoplastic monoclonal antibodies
High alert
An error with this medicine can cause serious harm: double checks and protocols are used.

An anti-CD20 antibody that destroys B cells; a backbone of lymphoma and CLL treatment, also used in rheumatoid arthritis and vasculitis.

Updated Nov 1, 2026

Also called: anti-CD20 antibody

Quick facts

Group: Antineoplastic monoclonal antibodies
Target: CD20 (B-lymphocyte surface antigen)
Used for: B-cell non-Hodgkin lymphomas · Pemphigus vulgaris
Key effects: Infusion reactions · Infections · Diarrhoea
Monitor: Hepatitis B surface antigen · Blood counts · Uric acid
ATC: L01FA01

No doses: the clinician sets them by the current guideline.

Mechanism of action

CD20 (B-lymphocyte surface antigen)Rituximab

The cryo-EM structure shows the CD20 protein in the membrane with rituximab Fab arms bound to its large extracellular loop.

Target in 3D: CD20 (B-lymphocyte surface antigen). PDB structure 6VJA (RCSB PDB, public domain). View the structure at RCSB PDB

Rituximab is a chimeric mouse–human IgG1 antibody against CD20, a membrane protein present on normal and malignant B cells but not on stem cells or plasma cells. Once bound, it kills the B cell mainly through complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity. Circulating and tissue B cells are depleted for months and recover gradually. In autoimmune diseases the benefit comes from removing B cells that drive the attack.

Binds CD20 on normal and malignant B cells
Complement and immune effector cells are recruited
B cells are lysed (CDC and ADCC)
B-cell depletion lasts months

Indications

B-cell non-Hodgkin lymphomas, alone or with chemotherapy (e.g. diffuse large B-cell and follicular lymphoma). Non-Hodgkin lymphoma →
Chronic lymphocytic leukaemia, with chemotherapy. Chronic lymphocytic leukaemia →
Rheumatoid arthritis after failure of a TNF inhibitor, with methotrexate. Rheumatoid arthritis →
Granulomatosis with polyangiitis. Granulomatosis with polyangiitis →
Microscopic polyangiitis. Microscopic polyangiitis →
Pemphigus vulgaris. Pemphigus vulgaris →

Adverse effects

Common

Infusion reactions: fever, chills, rigors, itching, mild low blood pressure, mostly with the first infusion
Infections (respiratory and others)
Diarrhoea, flushing, night sweats
Low neutrophils

Contraindications

Previous severe reaction to rituximab
Active severe infection, including untreated hepatitis B

Key interactions

Vaccines: Vaccination needs are reviewed before starting; vaccines are not given during treatment without checking with the treating team.

What is monitored

Hepatitis B surface antigen and core antibody before starting
Vital signs during each infusion
Blood counts
Immunoglobulin levels in long courses
New neurological signs (PML)
Uric acid, potassium and creatinine when tumour burden is high

Administration and safety

Intravenous infusion only, never as a push or bolus; the first infusion starts slowly and the rate is raised step by step.
Premedication (antihistamine, paracetamol and often a corticosteroid) is given before each infusion as ordered.
The intravenous and the subcutaneous (with hyaluronidase) products are not interchangeable; check the product and route.
Emergency drugs and equipment for anaphylaxis are at hand during the infusion.

Pregnancy and breastfeeding

Can harm the fetus; contraception is used during treatment and for months after, and breastfeeding is avoided.

Nursing care

Confirm hepatitis B screening before the first dose.
Vital signs before, during and after the infusion; stop and call the team if wheeze, swelling of the face, chest pain or hypotension appear.
Ask about fever, cough or other infections before each dose.
Teaching: report yellow skin, dark urine, confusion, weakness or vision change, and painful mouth or skin sores.

Pharmacokinetics

Absorption: Intravenous infusion (a subcutaneous form with hyaluronidase also exists).
Elimination: Removed like other IgG antibodies and partly by binding to B cells.
Half-life: About three weeks.

Test yourself

Think of the answer, then tap the question to see it.

What antigen does rituximab target, and which cells lack it?

CD20 on B cells; stem cells and plasma cells lack it.

Which test is mandatory before the first rituximab dose?

Hepatitis B serology (surface antigen and core antibody), because of the risk of reactivation.

A patient on rituximab develops progressive weakness and confusion months later. Which infection must be ruled out?

Progressive multifocal leukoencephalopathy caused by JC virus.

When are infusion reactions most frequent, and how are they reduced?

With the first infusion; premedication and a slow, stepwise rate reduce them.

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Connections

← Back to the class: Antineoplastic monoclonal antibodies

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Rituximab Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2022); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).

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Representative model, for educational purposes only.