Herceptin (trastuzumab) is a targeted anticancer treatment for certain HER2-positive cancers. It treats HER2-positive, early-stage, breast cancer (after breast surgery to remove the tumor) and late-stage, metastatic breast cancer (spread to other parts of the body). It can also treat HER2-positive, metastatic stomach cancer. Herceptin (trastuzumab) is most often used together with other anticancer medications, but can also be used by itself. Depending on the type of cancer, Herceptin (trastuzumab) can be injected into a vein (intravenous, IV) or under the skin (subcutaneous, SQ).
HER2-positive, breast cancers - IV and SQ injections
HER2-positive, metastatic stomach cancer - IV injection only
Herceptin (trastuzumab) is a monoclonal antibody that acts as a human epidermal growth factor receptor 2 (HER2) inhibitor. It blocks a specific protein in the body that’s important for cell growth called HER2. HER2 is found on both normal and cancer cells. Cancer cells usually have more HER2 proteins than normal cells. This can cause cancer cells to grow more quickly than normal cells. When HER2 is blocked by Herceptin (trastuzumab), cancer cells can’t grow and spread as well.
Source: DailyMed
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor or nurse immediately if any of the following side effects occur:
More common
Dizziness
fever or chills
headache
muscle aches
nausea or vomiting
skin rash
stuffy or runny nose
unusual tiredness or weakness
Less common
Bloody nose
difficult or labored breathing
ear congestion or pain
fast or irregular heartbeat
general feeling of discomfort or illness
head congestion
hoarseness or other voice changes
increased cough
joint pain
loss of appetite
pain or tenderness around the eyes and cheekbones
shivering
sweating
swelling of the feet or lower legs
tightness in the chest
trouble with sleeping
vomiting
Rare
Blue lips and fingernails
blurred vision
confusion
cough or hoarseness, accompanied by fever or chills
faintness or lightheadedness when suddenly getting up from a lying or sitting position
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, feet, or sex organs
lower back or side pain, accompanied by fever or chills
painful or difficult urination, accompanied by fever or chills
pale skin
redness of the skin
Incidence not known
Black, tarry stools
bloody or cloudy urine
sores, ulcers, or white spots in the mouth
unusual bleeding or bruising
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common
Numbness or tingling of the hands or feet
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Recommended treatment option for HER2-positive breast cancers and metastatic stomach cancer
More precise in the way it targets cancer cells compared to traditional chemotherapy
For breast cancers, can be given either as an injection under the skin or through a vein (IV), depending on preference
Short injection times (30 to 90 minutes IV; 2 to 5 minutes under the skin)
Requires regular visits to the clinic or infusion center to receive your dose
Can cause heart failure or other heart problems and requires regular monitoring of heart function
Not safe during pregnancy since it can harm an unborn baby
Herceptin (trastuzumab) is only used to treat cancers that have high levels of the HER2 protein (HER2-positive). Your provider will first test a sample of your tumor to see if your cancer is HER2-positive before starting treatment.
You might experience a reaction during or shortly after your Herceptin (trastuzumab) infusion, which can be life-threatening. Let your provider know or get help right away if you experience any infusion reactions like trouble breathing, hives, flushing, chest pain, skin turning blue, fast heartbeat, or dizziness.
You can feel some discomfort or pain at the injection site when receiving Herceptin (trastuzumab), either through the vein (IV) or injected under the skin (subcutaneously). Let your provider know if this is bothersome so they can manage it appropriately.
You’ll need regular monitoring of your heart while receiving Herceptin (trastuzumab) and for a few years after your last dose. This is because Herceptin (trastuzumab) can cause heart failure and other heart problems. Make sure to let your provider know right away if you experience any new or worsening shortness of breath, cough, swelling of your legs or feet, sudden weight gain, racing heartbeat, dizziness, or fainting. These can be signs of heart failure and you might need to stop taking this medication.
If you’re a female who can get pregnant, you should use birth control while receiving Herceptin (trastuzumab) and for 7 months after the last dose. This medication can cause harm to an unborn baby. Let your provider know right away if you become pregnant during Herceptin (trastuzumab) treatment.
Herceptin (trastuzumab) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk factors: Receiving Herceptin (trastuzumab) with other heart-damaging anticancer medications
Herceptin (trastuzumab) can cause new or worsening heart failure and affect how well your heart pumps blood through your body. Your risk of heart problems is higher if you’re receiving Herceptin (trastuzumab) with other heart-damaging anticancer medications. Make sure your provider has your full medical history, so they can closely monitor your heart through imaging using an echocardiogram or a MUGA scan. You’ll need to get this scan before starting treatment, about every 3 months while receiving Herceptin (trastuzumab), and a few more times after you complete treatment. Let your care team know if you experience any signs and symptoms of heart failure, including shortness of breath, dry cough, irregular heartbeats, chest pain, or weight gain.
Herceptin (trastuzumab) can cause infusion reactions, most commonly fever and chills. They can also include nausea, vomiting, pain, headache, dizziness, rash, and weakness. These reactions are usually mild and tolerable, but in rare cases, they can be serious. They can also happen during or several hours after the infusions. Alert your provider or get medical help right away if you experience any throat tightness, trouble breathing, fast heartbeat, fever, chills, hives, flushing, dizziness, or chest pain.
Risk factors: History of lung problems | Cancer tumors in the lung
Rare, but serious, lung problems, including inflammation of the lungs and fluid buildup in the lungs, have happened in people receiving Herceptin (trastuzumab). This can be related to signs of an infusion reaction. Let your provider know if you have difficulty breathing, cough, or fatigue during your treatment.
Herceptin (trastuzumab) can harm an unborn baby. This medication can affect the amount of amniotic fluid surrounding your baby in the womb. This can potentially cause developmental abnormalities and even death. Because of this risk, if you’re a female who can get pregnant, you should use birth control while receiving Herceptin (trastuzumab) and for 7 months after the last dose. Let your provider know right away if you become pregnant during this time.
In studies, people receiving Herceptin (trastuzumab) in combination with bone marrow-suppressing chemotherapy had more serious decreases in their white blood cell, red blood cell, and platelet levels compared to those receiving chemotherapy alone. This raises the risk of developing infections and bleeding or bruising. Let your provider know as soon as possible if you experience fevers, chills, or bleeding and bruising that doesn’t stop or go away. You might need to stop this medication.
Herceptin (trastuzumab) is given by a healthcare provider as an injection into a vein (IV) or as an injection under the skin (subcutaneous, SQ).
When given IV, the dose depends on your body weight. Your healthcare provider will determine the appropriate dose for you each time you receive the medication.
HER2-positive, breast cancers
IV injection: The typical dose is 4 mg/kg of bodyweight IV for the first injection, and then 2 mg/kg given once a week. It can also be given as 8 mg/kg for the first injection, and then 6 mg/kg every 3 weeks thereafter.
SQ injection (Herceptin Hylecta brand only): Herceptin Hylecta for injection under the skin contains trastuzumab and hyaluronidase. The typical dose is 600 mg/10,000 units (trastuzumab/hyaluronidase) given under the skin every 3 weeks. The SQ injection is a flat dose and isn’t dependent on weight.
HER2-positive, metastatic stomach cancer: The typical dose is 8 mg/kg IV for the first injection, and then 6 mg/kg every 3 weeks thereafter.
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
By signing up, I agree to GoodRx's Terms and Privacy Policy, and to receive marketing messages from GoodRx.
Research prescriptions and over-the-counter medications from A to Z, compare drug prices, and start saving.