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Trastuzumab is used for certain breast and stomach cancers. Common side effects include headaches, nausea, diarrhea, and trouble sleeping. If you can become pregnant, use effective birth control while you use this medicine and for seven months after your last dose. Tell your health care provider right away if you feel short of breath, have swelling of your ankles or leg, or gain more than five pounds in 24 hours.

Uses

What is trastuzumab used for?

Trastuzumab is commonly used for certain types of the following types of cancer.

Trastuzumab may also be used for other conditions as determined by your health care provider.

How does trastuzumab work (mechanism of action)?

Trastuzumab stops the growth and development of cancer cells that express large amounts of a protein called HER2. Your cancer cells can be tested to see if trastuzumab is a possible medicine for you.

How is trastuzumab supplied (dosage forms)?

Brands and other names

  • Herceptin
  • Hercessi
  • Herzuma
  • Kanjinti
  • Ogivri
  • Ontruzant
  • Trazimera

Dosage forms and strengths

Trastuzumab is available in an injectable form that is given by a health care provider.

How should I store trastuzumab?

Trastuzumab is usually given by a health care provider in a hospital or clinic. You will not store it at home.

Side Effects

What are the most common side effects of trastuzumab?

The most common side effects of trastuzumab are listed below. Side effects can vary based on why you are using trastuzumab. Tell your health care provider if you have any of these side effects that bother you.

  • Headache
  • Nausea or diarrhea
  • Fever or chills
  • Infection or common cold symptoms
  • Heart failure
  • Trouble sleeping
  • Coughing
  • Rash
  • Low neutrophil levels (neutropenia) (see below)
  • Tiredness
  • Anemia (low red blood cell levels)
  • Muscle or joint pain
  • Mouth sores
  • Flushing
  • Fluid retention (edema)
  • Change in how things taste

There may be other side effects of trastuzumab that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of trastuzumab?

While less common, the most serious side effects of trastuzumab are described below, along with what to do if they happen.

Severe Allergic Reactions. Trastuzumab may cause allergic reactions, which can be serious. Stop using trastuzumab and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Heart Problems. Trastuzumab can cause your heart to become larger, thick, hard, or stiff, which is also known as cardiomyopathy. This can make it harder for your heart to pump the way it normally would. Your health care provider may monitor your heart function while you are using trastuzumab. Keep all appointments, including appointments for testing. Tell your health care provider right away if you have any of the following symptoms of cardiomyopathy.

  • Shortness of breath
  • Coughing
  • Swelling in your ankles, feet, legs, or face 
  • Feeling of skipped heartbeats 
  • Gaining more than five pounds in 24 hours 
  • Dizziness

Infusion-related Reactions. Trastuzumab given by infusion into your vein can cause reactions that can be serious when it is given to you. Your infusion may need to be slowed or stopped if you have these reactions. Tell your health care provider right away if you have any of the following symptoms when you get your dose. 

  • Fever or chills
  • Headache
  • Dizziness
  • Feeling unusually weak or tired
  • Trouble breathing or shortness of breath
  • Chest pain
  • Low blood pressure or dizziness
  • Pain, which may or may not be at the location of your cancer
  • Rash
  • Nausea, vomiting, or diarrhea
  • Severe allergic reaction

Lung Problems. Trastuzumab can cause lung damage, fluid to build up in your lungs, and inflammation in your lungs, also called interstitial lung disease or pneumonitis. This can be serious or even life-threatening. These problems may be more serious if you already have lung problems, including lung cancer. Get emergency help if you have trouble breathing. You may also have a cough, fever, or chest pain.

Low Neutrophil Levels (Neutropenia). Trastuzumab may cause or worsen low levels of a type of white blood cell (called neutrophils), which is known as neutropenia. Neutrophils help prevent infection. Having a low level of neutrophils may increase your risk of infection. Tell your health care provider right away if you have any of the following symptoms of low neutrophil levels.

  • Fever, chills, or sweats
  • Tiredness
  • Sore throat, cough, or shortness of breath
  • Mouth or throat sores
  • Swollen lymph nodes

Warnings & Precautions

Who should not use trastuzumab?

Allergies to Ingredients. People who are allergic to any of the following should not use trastuzumab.

  • Trastuzumab
  • Herceptin
  • Hercessi
  • Herzuma
  • Kanjinti
  • Ogivri
  • Ontruzant
  • Trazimera
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific trastuzumab products they stock.

What should I know about trastuzumab before using it?

Trastuzumab is an intravenous (IV) medicine that you will receive at a hospital or clinic. You may get medicines before trastuzumab to reduce your risk of having a reaction to your dose. See the Side Effects section for more details.

People who are 65 or older can be at greater risk of some side effects from trastuzumab. Talk to your health care provider about your risks if you are in this age group.

What should I tell my health care provider before using trastuzumab?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if trastuzumab is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Lung or breathing problems
  • Heart problems
  • Tumor invading the lungs 
  • Shortness of breath at rest
  • Low levels of white blood cells
  • Recent chemotherapy

Other Medicines and Supplements. Trastuzumab may interact with other medicines and supplements. Before using trastuzumab, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Trastuzumab can harm an unborn baby. You may need a test to confirm that you are not pregnant before using trastuzumab. Use effective birth control while using trastuzumab and for seven months after your last dose. Tell your health care provider right away if you are, think you are, or plan to become pregnant. 

Breastfeeding. It is not known if trastuzumab passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should use trastuzumab while breastfeeding.

Interactions

Does trastuzumab interact with foods or drinks?

There are no known interactions between trastuzumab and foods or drinks.

It is unknown if drinking alcohol will affect trastuzumab. The risk of tiredness or trouble sleeping may be increased if you drink alcohol while using trastuzumab.

Does trastuzumab interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using an anthracycline medicine, such as daunorubicin, doxorubicin, or epirubicin, before using trastuzumab.

This may not be a complete list of medicines that can interact with trastuzumab. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much trastuzumab?

If you or someone else has used too much trastuzumab, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of trastuzumab?

Trastuzumab is usually given by a health care provider in a hospital. Your health care provider will make sure you are receiving trastuzumab as scheduled.

If you miss an appointment to get your trastuzumab dose, call to make another appointment as soon as possible.