Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who receives Herceptin (Trastuzumab). If you are concerned about side effects, discuss the risks and benefits of Herceptin (Trastuzumab) with your doctor.

The following side effects have been reported by at least 1% of people receiving Herceptin (Trastuzumab). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• appetite loss
• changes in nails
• Constipation
• cough
• fatigue
• Fever and chills
• headache
• mild Diarrhea
• nausea
• pain (e.g., muscle and joint pain)
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• diarrhea (more than 4 extra bowel movements a day or any at night)
• fast heartbeat
• itching
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
• symptoms of an infusion reaction (e.g., itching, wheezing, dizziness, fast heart rate)
• symptoms of Anemia (e.g., shortness of breath, tiredness, fast heart rate)
• symptoms of heart problems (e.g., swelling of feet or lower legs, shortness of breath)
• symptoms of infection (e.g., fever or chills, sore throat, cough, redness or swelling, painful urination)
• symptoms of kidney problems (e.g., decreased urine production; drowsiness; shortness of breath; fatigue; swelling of the legs, ankles, or feet)
• symptoms of lung problems (e.g., shortness of breath, wheezing, or coughing)
• trouble swallowing

Seek immediate medical attention if any of the following occur:

• chest pain
• shortness of breath
• symptoms of an allergic reaction (e.g., Hives; dizziness; fast heart rate; difficulty breathing; swelling of the lips, tongue, or throat)
• wheezing

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Herceptin (Trastuzumab).

Each vial of sterile, white-to-pale yellow lyophilized powder for IV administration, under vacuum, contains Herceptin (Trastuzumab) 440 mg. Nonmedicinal ingredients: α,α-trehalose dihydrate, L-histidine HCl, L-histidine, and polysorbate 20. Preservative-free. Bacteriostatic water for injection supplied as a 20 mL vial of sterile solution containing 1.1% benzyl alcohol (as antimicrobial preservative), yields 21 mL of a multi-dose solution containing 21 mg/mL of Herceptin (Trastuzumab).

Herceptin (Trastuzumab) should not be used by anyone who is allergic to Herceptin (Trastuzumab), murine proteins, Chinese hamster ovary (CHO) cell proteins, or to any of the ingredients of the medication.

There may be an interaction between Herceptin (Trastuzumab) and any of the following:

• Abatacept
• Adalimumab
• Anakinra
• Azathioprine
• Belimumab
• corticosteroids (e.g., budesonide, Dexamethasone, Hydrocortisone, fluticasone, Prednisone)
• Cyclosporine
• Daclizumab
• eculizumab
• Etanercept
• Fingolimod
• Glatiramer
• Golimumab
• Guselkumab
• Infliximab
• Ixekizumab
• Leflunomide
• mycophenolate
• other medications to treat cancer (e.g., Carboplatin, Cyclophosphamide, Doxorubicin, Ifosfamide, Vincristine)
• Natalizumab
• Ocrelizumab
• Romidepsin
• Sarilumab
• Secukinumab
• siltuximab
• Sirolimus
• Tacrolimus
• Teriflunomide
• Tocilizumab
• Tofacitinib
• Ustekinumab
• Vedolizumab

If you are receiving any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Herceptin (Trastuzumab). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Herceptin (Trastuzumab).

Allergic reactions: Herceptin (Trastuzumab) may cause an allergic reaction (e.g., dizziness; hives; fast heart rate; swelling of the lips, tongue, or throat). If you experience these symptoms, tell your doctor immediately.

Heart disease: Herceptin (Trastuzumab) can cause heart problems such as heart failure. People with heart disease are more at risk for these problems. Your doctor will perform tests at regular intervals to monitor for any changes in your heart function. If you experience symptoms of heart function changes such as shortness of breath, worsening cough, difficulty breathing at night, swelling of the feet or hands, contact your doctor immediately.

Infection: As well as killing cancer cells, Herceptin (Trastuzumab) can reduce the number of cells that fight infection in the body (white blood cells). Avoid contact with people who have contagious infections and tell your doctor if you begin to notice signs of an infection, such as fever or chills.

Infusion reactions: Herceptin (Trastuzumab) can cause reactions that are related to the infusion. Symptoms of a reaction include itching, dizziness, wheezing, fast heart rate, difficulty breathing, and a dramatic drop in blood pressure. The reaction does not usually last very long, but may need to be treated as it can cause death if it is severe. The reaction usually occurs during or shortly after receiving the medication, but can also be delayed. If you experience symptoms of an infusion reaction, let your nurse or doctor know immediately or get immediate medical attention.

Lung problems: Herceptin (Trastuzumab) can cause lung problems, especially for people with lung disease or Lung Cancer, or who have received or are receiving other anticancer medications or radiation therapy. Let your doctor know immediately if you begin to experience shortness of breath or persistent cough.

Preservative: The intravenous form of Herceptin (Trastuzumab) contains benzyl alcohol, which acts as a preservative. Inform a member of your health care team if you have had a previous reaction to benzyl alcohol.

Pregnancy: Herceptin (Trastuzumab) can cause harm to the fetus if used during pregnancy. Women who could become pregnant should use effective contraception while receiving Herceptin (Trastuzumab) and for 7 months after stopping it. If you become pregnant while taking Herceptin (Trastuzumab), contact your doctor immediately.

Breast-feeding: It is not known if Herceptin (Trastuzumab) passes into breast milk. If you are a breast-feeding mother and are receiving Herceptin (Trastuzumab), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Herceptin (Trastuzumab) have not been established for children.

Seniors: Seniors may be more at risk for experiencing certain side effects from Herceptin (Trastuzumab).