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Gemtuzumab Side Effects

For the Consumer

Applies to gemtuzumab: intravenous solution reconstituted

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
  • Signs of infection like fever, chills, very bad sore throat, ear or sinus pain, cough, more sputum or change in color of sputum, pain with passing urine, mouth sores, or wound that will not heal.
  • Signs of bleeding like throwing up blood or throw up that looks like coffee grounds; coughing up blood; blood in the urine; black, red, or tarry stools; bleeding from the gums; vaginal bleeding that is not normal; bruises without a reason or that get bigger; or any bleeding that is very bad or that you cannot stop.
  • Signs of electrolyte problems like mood changes, confusion, muscle pain or weakness, a heartbeat that does not feel normal, seizures, not hungry, or very bad upset stomach or throwing up.
  • Stomach swelling or fast weight gain.
  • Fever or chills.
  • A fast heartbeat.
  • A heartbeat that does not feel normal.
  • Very bad dizziness or passing out.
  • Shortness of breath.
  • Not able to pass urine or change in how much urine is passed.
  • This drug can cause a very bad and sometimes deadly bowel problem (neutropenic enterocolitis). Call your doctor right away if you have stomach pain with or without a fever.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Upset stomach or throwing up.
  • Hard stools (constipation).
  • Mouth irritation or mouth sores.
  • Headache.
  • Feeling tired or weak.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at

For Healthcare Professionals

Applies to gemtuzumab: intravenous powder for injection


Very common (10% or more): Bleeding (25%), thrombocytopenia (24%), febrile neutropenia (18%)
Common (1% to 10%): Hemorrhage
Frequency not reported: Myelosuppression, anemia[Ref]


Very common (10% or more): Fever (79%), fatigue (46%)
Common (1% to 10%): Pain
Frequency not reported: Chills[Ref]


Very common (10% or more): Nausea (21%), vomiting (21%), constipation (21%), mucositis (21%)
Common (1% to 10%): Diarrhea
Postmarketing reports: Neutropenic colitis (sometimes fatal)[Ref]


Common (1% to 10%): Pneumonia, lung edema
Frequency not reported: Hypoxia, respiratory failure, dyspnea
Postmarketing reports: Fungal lung infections (including Pulmonary mycosis and Pneumocystis jirovecii pneumonia) (sometimes fatal), interstitial pneumonia (sometimes fatal)[Ref]


Very common (10% or more): Increased AST (40%), increased ALT (16%)
Common (1% to 10%): Veno-occlusive liver disease (VOD) (sometimes fatal), hyperbilirubinemia[Ref]


Postmarketing reports: Hemorrhagic cystitis (sometimes fatal)
Genitourinary side effects have included vaginal hemorrhage (12%) and hematuria (10%)[Ref]


Very common (10% or more): Infection (44%), sepsis (32%)
Postmarketing reports: Bacterial infections (including Stenotrophomonas infection), potential for immunogenicity[Ref]


Frequency not reported: Renal failure secondary to tumor lysis syndrome[Ref]


Common (1% to 10%): Tachycardia
Frequency not reported: QT interval prolongation, hypotension[Ref]


Very common (10% or more): Rash (16%)[Ref]

Nervous system

Very common (10% or more): Headache (19%)[Ref]


Very common (10% or more): Hypophosphatemia (64%), hypokalemia (57%), hyponatremia (44%), alkaline phosphatase increased (13%), aspartate aminotransferase increased (14%), alanine aminotransferase increased (10%)
Common (1% to 10%): Blood bilirubin increased[Ref]


Frequency not reported: Hypersensitivity (including anaphylaxis)[Ref]


1. "Product Information. Mylotarg (gemtuzumab)" Wyeth-Ayerst Laboratories, Philadelphia, PA.

Some side effects of gemtuzumab may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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.