Trastuzumab (Herceptin)

Trastuzumab (pronounced [tras TU zoo mab]) is also known by the brand name Herceptin. Herceptin is an antineoplastic (anti-cancer) drug that belongs to a class called Anti-HER2. It is a type of chemotherapy that prevents cancer cells from multiplying and restricts their growth.

What Is Chemotherapy?

Chemotherapy is a cancer treatment in which certain drugs are used to kill cancerous cells. These drugs are usually cytotoxic chemical substances that are toxic to the cells, restrict their growth, prevent their division, and ultimately kill the cells. 

How Is Herceptin Used?

Herceptin has been approved by the Food and Drug Administration (FDA) to treat different types of breast cancer, endometrial cancer, and stomach cancer. It can be prescribed alone or with other anti-cancer medications

Available Formulations

Herceptin is available as a solution for intravenous injection only. It is most commonly available in 150 mg strength. The total duration of therapy typically should not exceed 1 year (52 weeks), but this may vary depending on the patient’s condition and cancer severity. 

Directions for Use

Herceptin is typically dosed to be given once every 1 to 3 weeks, depending on cancer type and severity. Verify the correct dose and frequency with your provider. The dose should not be more or less than what is prescribed. The dose is determined using the patient’s body weight. The initial dose (also known as the loading dose) is typically infused over 90 minutes if tolerated, and subsequent infusions (maintenance doses) can be infused over 30 – 90 minutes. 

Do not administer Herceptin with dextrose in water (D5W) or with any other medications. It should be mixed with bacteriostatic or sterile water for injection only and diluted with normal saline. Herceptin should NOT be administered as an IV push or rapid bolus. Trastuzumab is available alone or in combination with other drugs. Different trastuzumab products are NOT interchangeable; only administer exact medication prescribed.

Missed Dose

This medicine needs to be administered on a fixed schedule. If you miss a dose, contact your physician for further instructions immediately. 

Typically, if the dose is missed by one week or less, the usual maintenance dose should be given as soon as possible (do not wait until the next planned cycle). Subsequent maintenance doses should be administered 1 to 3 weeks later (based on the patient’s normal maintenance dose schedule).

If a dose is missed by over one week, a re-loading dose should be administered over 90 minutes as soon as possible. The usual maintenance dose is then administered 1 to 3 weeks later (based on the patient’s normal maintenance dose schedule).


As there are lots of different variations of trastuzumab, storage times vary by product; refer to the individual product labeling for details. Prior to reconstitution, vials should be stored in the refrigerator. Some products should be stored in intact vials in the original carton to protect from light. Some solutions are preservative-free, and therefore, they should be used immediately. Others can be refrigerated for up to 24 hours (depending on the product or vial size). Do not freeze or shake Herceptin vials. 

What To Avoid While Taking Herceptin

While taking Herceptin therapy, you must follow some precautions. Always tell your physician about any medications you are already taking. Do not take any drug or medicine (even herbals, vitamins, or over-the-counter medications) without prior consent from your physician or pharmacist. They may have some significant interactions with Herceptin.

Pregnancy and Herceptin

Exposure to Herceptin during pregnancy may result in a decrease in amniotic fluid, which can severely impact the fetus and lead to delayed growth and malformations. Pregnancy status must be checked prior to starting Herceptin therapy in women of childbearing age, and effective contraception must be used during treatment and for 7 months after the last dose. Herceptin may cause fetal harm and is therefore not recommended for women who are breastfeeding during therapy. Breastfeeding should also be avoided for at least 7 months after the last dose. 

Side Effects

As with any other medication, you may encounter side effects while taking Herceptin. A few things to remember are:

  • You may not have all the side effects listed below. Many people may experience little to no side effects.
  • The severity of side effects may vary from person to person, so don’t compare your side effects with other people’s experiences.
  • Most of the side effects will improve when therapy is discontinued.
  • These side effects are easily manageable most of the time, either by readjusting the dose of Herceptin or using additional medications to treat the symptoms. Consult with your physician or pharmacist to explore available options.
  • Do not hide any symptoms; if you feel any discomfort, do not hesitate to tell your physician or pharmacist about it.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions. 

Some of the more serious side effects of Herceptin are listed below:

Weight Loss

It is common for Herceptin to cause weight loss due to decreased appetite while taking this medication. 

Cardiac Complications 

There may be cardiac complications with the use of Herceptin like hypertension, left ventricular heart failure (LVHF), arrhythmias, or thromboembolism (which can include heart attack or stroke). Hypertension can be managed with antihypertensive therapy. Monitoring for LVHF is warranted prior to initiation of therapy, every 3 months during therapy, and every 6 months for 2 years after therapy is completed. 

Kidney Complications

Herceptin may cause kidney complications, leading to a condition called glomerulopathy, and can lead to heart failure if left untreated. Glomerulopathy is a syndrome where protein leaks out of the kidneys and is found in the urine. This can be detected by taking a urine test at the doctor’s office. 

Hepatitis B Reactivation

There is a high chance of getting hepatitis B with Herceptin use. It is essential to screen for hepatitis B prior to initiating Herceptin therapy. Signs of hepatitis B include yellowing of the skin and eyes or excessive tiredness. If you have any of these symptoms, seek medical advice from your physician immediately. 

Lung Damage

In some cases, Herceptin can potentially cause lung damage and conditions like acute respiratory distress syndrome (ARDS), pulmonary fibrosis, pulmonary edema (fluid in lungs), and others. Lung effects usually occur within 24 hours after administration. Patients with preexisting lung conditions may be at a higher risk. If you experience difficulty breathing, seek medical help immediately. 

Bone, Joint, Back, and Muscle Pain

Another common side effect is bone, joint, back, or muscle pain. Adequate rest and hydration may help reduce potential pain. Get physician approval prior to taking any over-the-counter medications for pain relief.

Infusion-related Reactions

Infusion-related reactions with Herceptin treatment most commonly occur during treatment or within 24 hours after the first infusion. Infusion reactions may consist of fever and chills, and may also manifest as nausea, vomiting, headache, dyspnea, dizziness, rash, hypotension, and weakness. If shortness of breath, swelling of the mouth or tongue, or drop in blood pressure occurs, the infusion should be stopped immediately. If you experience a severe infusion reaction, the infusion can be re-attempted with appropriate premedications like Tylenol or Benadryl.

Other common side effects may include:

  • Nausea or vomiting
  • Diarrhea
  • Flu or cold-like symptoms
  • Abdominal pain
  • Change in taste
  • Trouble sleeping
  • Mouth sores or irritation


Unless approved by your physician, Herceptin is generally not recommended in patients with a risk of cardiac complications.

  • Risk factors can include a history of heart disease, high blood pressure, high amounts of fat or cholesterol in blood (dyslipidemia), history of heart attack or stroke, etc. 
  • Herceptin is known for causing left ventricular heart failure. If signs of LVHF are apparent, discontinuation may be warranted. 
  • Patients with other conditions (like diabetes, obesity, smoking, and being 60 or older) may also be at a higher risk for cardiac complications. 


Is Herceptin a chemo agent?

Chemo drugs are those that are used in the management of various cancers. Herceptin kills the cancer cells. Thus, it is a chemo agent that is advised as a treatment option for various cancer patients. 

How should Herceptin be taken?

Herceptin is available as an intravenous injection only. It is typically dosed to be given once every 1 to 3 weeks, depending on cancer type and severity. The dose is determined using the patient’s body weight. The loading dose is typically infused over 90 minutes if tolerated, and subsequent infusions (maintenance doses) are typically infused over 30 – 90 minutes.


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Dr. Dania Jaradat, PharmD was born and raised in Torrance, California. She graduated from Marshall B. Ketchum University. The most rewarding part of her job is to keep the line between pharmacist and patient open and to educate patients on medication management. In her free time, she enjoys traveling to different countries, spending time with her husband and son, and reading. See Author Biography