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Tositumomab Side Effects

For the Consumer

Applies to tositumomab: intravenous solution

As well as its needed effects, tositumomab may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking tositumomab, check with your doctor or nurse immediately:

More common:
  • Bleeding gums
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • blurred vision
  • bone pain
  • chest pain
  • chills
  • confusion
  • constipation
  • cough
  • coughing up blood
  • depressed mood
  • difficulty with breathing
  • difficulty with swallowing
  • dizziness
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • dry skin and hair
  • fast heartbeat
  • feeling cold
  • fever or chills
  • hair loss
  • headache
  • hives
  • hoarseness or husky voice
  • increased menstrual flow or vaginal bleeding
  • itching
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • lower back or side pain
  • muscle cramps and stiffness
  • noisy breathing
  • nosebleeds
  • painful or difficult urination
  • pale skin
  • paralysis
  • pinpoint red spots on the skin
  • prolonged bleeding from cuts
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rapid weight gain
  • red or black, tarry stools
  • red or dark brown urine
  • shortness of breath
  • skin rash
  • slowed heartbeat
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • sweating
  • swollen glands
  • tightness in the chest
  • tingling of the hands or feet
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight gain or loss
  • wheezing
Less common:
  • Feeling of warmth or heat
  • flushing or redness of the skin, especially on the face and neck

Severity: Minor

Some tositumomab side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Acid or sour stomach
  • back pain
  • belching
  • body aches or pain
  • congestion
  • diarrhea or increased bowel movements
  • difficult or labored breathing
  • difficulty with moving
  • dryness or soreness of the throat
  • heartburn
  • indigestion
  • itching skin
  • joint pain
  • lack or loss of strength
  • loose or liquid stools
  • loss of appetite
  • muscle aches or pains
  • nausea or feeling of upset stomach or feeling like you may vomit
  • neck pain
  • runny nose
  • stomach discomfort, upset, or pain
  • sudden sweating
  • swelling of the hands, ankles, feet, or lower legs
  • swollen joints
  • tender, swollen glands in the neck
  • trouble with swallowing
  • voice changes
  • vomiting
  • weight loss
Less common:
  • Sleepiness or unusual drowsiness

For Healthcare Professionals

Applies to tositumomab: intravenous kit


Common (1% to 10%): Hypotension, vasodilation[Ref]


Very common (10% or more): Rash, pruritus
Common (1% to 10%): Sweating[Ref]


Common (1% to 10%): Hypothyroidism[Ref]


Very common (10% or more): Abdominal pain, nausea, vomiting, diarrhea, anorexia
Common (1% to 10%): Constipation, dyspepsia[Ref]


Very common (10% or more): Neutropenia, thrombocytopenia, anemia[Ref]


Common (1% to 10%): Allergic (hypersensitivity) reactions (allergic reaction, facial edema, injection site hypersensitivity, anaphylactic reaction, laryngismus, serum sickness)
Postmarketing reports: Hypersensitivity reactions including fatal anaphylaxis[Ref]


Very common (10% or more): Positive serology for human anti-mouse antibodies (HAMA)[Ref]


Frequency not reported: Infusion reactions[Ref]


Common (1% to 10%): Peripheral edema, weight loss[Ref]


Very common (10% or more): Myalgia, arthralgia
Common (1% to 10%): Back pain, neck pain[Ref]

Nervous system

Common (1% to 10%): Dizziness, somnolence
Postmarketing reports: Axonal neuropathy leading to quadriparesis[Ref]


Common (1% to 10%): Secondary malignancies (non-melanoma skin, colorectal, head and neck, breast, lung, bladder, melanoma, gastric)
Frequency not reported: Secondary leukemia, myelodysplastic syndrome[Ref]


Very common (10% or more): Asthenia, fever, infections, pain, chills, headache
Common (1% to 10%): Chest pain, serious infections (pneumonia, bacteremia, septicemia, bronchitis, skin infections)[Ref]


Very common (10% or more): Cough, pharyngitis, dyspnea, rhinitis
Common (1% to 10%): Pneumonia[Ref]


1. "Product Information. Bexxar I 131 Therapeutic (iodine I 131 tositumomab)." GlaxoSmithKline, Research Triangle Park, NC.

2. "Product Information. BexxarTherapy (tositumomab)." GlaxoSmithKline Inc, Oakville, IA.

It is possible that some side effects of tositumomab may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.