Trastuzumab is a cancer medication that interferes with the growth and spread of cancer cells in the body.

Trastuzumab is used to treat certain types of breast cancer or stomach cancer. Other cancer medicines are sometimes used in combination with trastuzumab.

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

Do not use trastuzumab if you are pregnant. It could harm the unborn baby. Avoid becoming pregnant for at least 7 months after your last dose of trastuzumab.

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 caregiver right away if you feel dizzy, nauseated, light-headed, weak, short of breath, or if you have a headache, fever, chills, sudden chest pain, wheezing, dry cough, hives, or swelling of your face, lips, tongue, or throat.

You should not use trastuzumab if you are allergic to it.

To make sure trastuzumab is safe for you, 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)

Do not use trastuzumab if you are pregnant. It could harm the unborn baby. Tell your doctor if you become pregnant during treatment. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 7 months after your treatment ends.

If you become pregnant while using this medicine or within 7 months after you stop, your name may need to be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of trastuzumab on the baby.

It is not known whether trastuzumab passes into breast milk or if it could harm a nursing baby. You should

not breast-feed while using this medicine.

Trastuzumab is injected into a vein through an IV. You will receive this injection in a clinic or hospital setting. Trastuzumab must be given slowly, and the IV infusion can take up to 90 minutes to complete.

You may need to undergo a biopsy to make sure trastuzumab is the right medicine to treat your cancer.

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

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 of these tests.

Trastuzumab side effects

Some side effects may occur during the injection. Tell your caregiver right away if you feel dizzy, nauseated, light-headed, weak, short of breath, or if you have a headache, fever, chills, sudden chest pain, wheezing, dry cough, hives, or swelling of your face, lips, tongue, or throat.

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

Call your doctor at once if you have:

shortness of breath (even with mild exertion or while lying down);

rapid or shallow breathing, grunting, gasping for breath, pain when you breathe;

blue-colored skin or lips;

sudden chest pain or discomfort, wheezing, new or worsening cough;

pounding heartbeats or fluttering in your chest;

swelling, rapid weight gain;

fever, swollen gums, painful mouth sores, pain when swallowing, skin sores, cold or flu symptoms; or

heart attack symptoms--chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating.

Common side effects may include:

nausea, diarrhea, weight loss;

headache, sleep problems (insomnia), tiredness;

mouth sores;

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

skin rash, bruising, pale skin;

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.

What other drugs will affect trastuzumab?

Other drugs may interact with trastuzumab, including prescription and over-the-counter medicines, vitamins, and herbal products.