Trastuzumab is used to treat certain types of breast cancer or stomach cancer, sometimes in combination with other cancer medicines.

trastuzumab is sometimes used when the cancer has spread to other parts of the body (metastatic).

Trastuzumab may also be used for purposes not listed in this medication guide.

Do not use if you are pregnant. Use effective birth control, and tell your doctor if you become pregnant during treatment.

Trastuzumab can cause heart failure, especially if you have heart disease or if you are also receiving certain other cancer medicines.

Some side effects may occur during the injection. Tell your caregivers if you feel dizzy, nauseated, light-headed, weak, short of breath, or if you have a headache, fever, or chills.

Your doctor will perform a medical test to make sure trastuzumab is the right medicine to treat your cancer.

Trastuzumab is given as an infusion into a vein. A healthcare provider will give you this injection.

Trastuzumab is usually given once every week or every 1 to 3 weeks. Follow your doctor's dosing instructions very carefully.

This medicine must be given slowly, and the infusion can take up to 90 minutes to complete.

You may need frequent medical tests to be sure this medicine is not causing harmful effects. Your cancer treatments may be delayed based on the results.

Your heart function may need to be checked before and during treatment with trastuzumab. You may also need heart function testing every 6 months for 2 years after your last dose of this medicine.

Trastuzumab is usually given for 52 weeks, or until your body no longer responds to the medication.

Tell your doctor if you have ever had:

• heart disease;

• congestive heart failure;

• a heart attack; or

• any allergies or breathing problems.

Trastuzumab can cause heart failure, especially if you have heart disease or if you are also receiving certain other cancer medicines (such as daunorubicin, doxorubicin, epirubicin, or idarubicin).

You may need to have a negative pregnancy test before starting this treatment.

Do not use trastuzumab if you are pregnant. trastuzumab can cause injury or death to the unborn baby. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 7 months after your last dose. Tell your doctor if you become pregnant.

If you become pregnant while using trastuzumab or within 7 months after you stop, your name may be listed on a pregnancy registry to track the effects of trastuzumab on the baby.

It may not be safe to breastfeed while using this medicine and for up to 7 months after your last dose. Ask your doctor about any risk.

Call your doctor for instructions if you miss an appointment for your trastuzumab injection.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Some side effects may occur during the injection, or in the days afterward. Tell your caregiver right away if you feel dizzy, nauseated, itchy, light-headed, weak, short of breath, or if you have a headache, fever, chills, or chest pain.

Trastuzumab may cause serious side effects. Call your doctor at once if you have:

• new or worsening cough;

• a light-headed feeling, like you might pass out;

• severe headache, blurred vision, pounding in your neck or ears;

• blisters or ulcers in your mouth, red or swollen gums, trouble swallowing;

• heart problems--pounding heartbeats, dizziness, swelling in your lower legs, rapid weight gain, feeling short of breath;

• low blood cell counts--fever, chills, tiredness, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed; or

• signs of tumor cell breakdown--tiredness, weakness, muscle cramps, nausea, vomiting, diarrhea, fast or slow heart rate, tingling in your hands and feet or around your mouth.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common side effects of trastuzumab may include:

• heart problems;

• nausea, diarrhea, weight loss;

• headache;

• trouble sleeping, feeling tired;

• low blood cell counts;

• rash;

• fever, chills, cough, or other signs of infection;

• mouth sores;

• altered sense of taste; or

• cold symptoms such as stuffy nose, sinus pain, sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Other drugs may affect trastuzumab, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Trastuzumab can have long lasting effects on your heart, especially if you receive other cancer medicines. For at least 7 months after your last dose of trastuzumab, tell any doctor who treats you that you have used trastuzumab.