Herceptin (trastuzumab) is a brand-name solution for IV infusion that’s prescribed for certain types of cancer. As with other drugs, Herceptin can cause side effects, such as heart problems that may last long term.

Herceptin is approved by the Food and Drug Administration (FDA) for use in adults in certain situations to treat:

  • breast cancer that’s HER2-positive
  • breast cancer that’s HER2-positive and metastatic
  • stomach cancer that’s HER2-positive and metastatic
  • a type of digestive system cancer called gastroesophageal junction adenocarcinoma that’s HER2-positive and metastatic

Your doctor will order a genetic test to see if your cancer is treatable with Herceptin. For treating breast cancer, your doctor may prescribe Herceptin alone or in combination with other drugs. For treating stomach cancer, they may prescribe Herceptin with other cancer medications.

Read on to find out about potential common, mild, and serious side effects.

These are just a few of the more common side effects reported by people who took Herceptin in clinical studies. These side effects can vary depending on which condition the drug is treating.

More common side effects in people receiving Herceptin for breast cancer that’s HER2-positive include:

More common side effects in people receiving Herceptin for breast cancer that’s HER2-positive and metastatic include:

More common side effects in people receiving Herceptin for stomach cancer or gastroesophageal junction adenocarcinoma that’s HER2-positive and metastatic include:

  • neutropenia (low levels of white blood cells)
  • diarrhea
  • fatigue
  • anemia (low levels of red blood cells)
  • stomatitis (swelling or sores inside your lips, mouth, throat, or cheeks)

* Herceptin has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA.
† To learn more about this side effect, see the “Side effect specifics” section below.

Mild side effects can occur with Herceptin use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Herceptin’s prescribing information.

Mild side effects that have been reported with Herceptin include:

These side effects may be temporary, lasting a few days or weeks. But if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the FDA approves a drug, it tracks side effects of the medication. If you develop a side effect while receiving Herceptin and want to tell the FDA about it, visit MedWatch.

* To learn more about this side effect, see the “Side effect specifics” section below.

Herceptin may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Herceptin’s prescribing information.

If you develop serious side effects while receiving Herceptin, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported include:

  • Blood clots. Symptoms can include:
    • chest pain
    • loss of strength in an arm or leg
    • pain or swelling in your arms or legs
    • shortness of breath
  • Tumor lysis syndrome (the release of harmful substances into your blood due to cancer cells breaking down). Symptoms can include:
  • Neutropenia. Symptoms can include:
  • Anemia. Symptoms can include:
    • dizziness
    • fatigue
    • skin or gums that appear pale
  • Thrombocytopenia (low levels of platelets, which are a type of blood cell). Symptoms can include:
    • bleeding that lasts for a long time or won’t stop on its own
    • bruising easily, which may cause brown, purple, or red bruises
    • nosebleeds
  • Kidney problems, such as kidney damage or kidney failure. Symptoms can include:
    • dark-colored urine
    • dizziness
    • itching
    • making less urine than usual
    • fluid retention
  • Peripheral neuropathy (damage to your nerves). Symptoms can include:
    • numbness, pain, or tingling, such as in your arms, legs, hands, or feet
  • Boxed warnings:
    • heart problems*†
    • lung problems*†
    • infusion reaction*†
    • harm to a fetus*‡
  • Allergic reaction.†

* Herceptin has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA.
† To learn more about this side effect, see the “Side effect specifics” section below.
‡ For more information, see “Pregnancy and breastfeeding while receiving Herceptin” in the “Precautions for Herceptin” section below.

Long-term side effects

Most of the side effects Herceptin may cause are usually temporary. They typically last a few days or weeks.

But Herceptin may cause long-term side effects as well. For example, some heart problems due to the drug may not go away. (Herceptin has a boxed warning about heart problems. To learn more, see “Boxed warnings” in the “Side effect specifics” section below.)

If you have side effects from Herceptin that bother you, become severe, or don’t go away, be sure to talk with your doctor.

Herceptin may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Is hair loss one of Herceptin’s side effects?

People receiving Herceptin in clinical trials didn’t report hair loss as a side effect.

But some of the drugs that you may take with Herceptin can cause hair loss. (Herceptin may be used alone or in combination with other medications.)

Other drugs that you may take with Herceptin and can cause hair loss as a side effect include:

If you’re concerned about hair loss during your treatment with Herceptin and other drugs, talk with your doctor or pharmacist. They may be able to suggest ways to help prevent or lessen this side effect.

How long do Herceptin side effects last?

Most side effects Herceptin may cause are usually temporary, lasting a few days or weeks.

But Herceptin may cause some long-term side effects. For more information, see “Long-term side effects” above.

To learn more about how long Herceptin side effects may last for you, talk with your doctor.

Are there lab tests to check for side effects caused by Herceptin?

Yes, your doctor may order lab tests, such as blood and urine tests, to check for certain side effects during your Herceptin treatment.

These side effects can include:

  • anemia
  • thrombocytopenia
  • neutropenia
  • kidney problems, such as kidney damage or kidney failure
  • heart problems,* such as high blood pressure or heart failure

Your doctor can give you more information about the lab tests they’ll order while you receive Herceptin.

* Herceptin has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section above.

Learn more about some of the side effects that Herceptin may cause.

Boxed warnings

Herceptin has several boxed warnings. A boxed warning is a serious warning from the FDA.

Heart problems: Herceptin use can cause heart problems, including heart failure, high blood pressure, and arrhythmia. Receiving Herceptin with medications called anthracyclines can increase this risk. Examples of anthracyclines include doxorubicin and daunorubicin (Cerubidine).

Lung problems: Herceptin can cause serious lung problems, but this is rare. The problems may include shortness of breath, fluid buildup in your lungs, and lung inflammation called interstitial pneumonitis. Herceptin is given as an IV infusion. This administration method may cause lung problems. (To learn more, see “Infusion reaction” below.)

Symptoms of serious lung problems can include shortness of breath, cough, and chest pain or tightness.

Infusion reaction: Herceptin is given as an IV infusion, which is an injection that’s slowly dripped into your vein over time. It’s possible to have a reaction to the infusion. The reactions can include symptoms such as low blood pressure and angioedema (swelling under your skin, usually caused by an allergic reaction).

In rare cases, anaphylaxis can occur. This is a life threatening allergic reaction. Symptoms can include:

What you can do

Here’s some information about managing the boxed warnings of Herceptin mentioned above.

How to manage heart and lung problems: Your doctor will make sure your body is healthy enough for treatment with Herceptin before you start. This typically includes having tests to check your heart and lung function before and during your Herceptin treatment. Be sure to tell your doctor about any heart or lung conditions you may have.

If you notice any of the following symptoms of serious heart or lung problems while receiving Herceptin, talk with your doctor immediately:

  • shortness of breath
  • cough
  • fluid retention in your ankles, legs, or face
  • weight gain of more than 5 pounds (about 2.3 kilograms) over 24 hours
  • dizziness
  • loss of consciousness

If you have heart problems while receiving Herceptin, your doctor will likely have you stop taking the drug.

How to manage infusion reactions: If you have an infusion reaction while receiving Herceptin, your doctor may recommend medications, such as diphenhydramine (Benadryl), to take before your next infusion. These may help prevent infusion reactions if you have had one previously. In other situations, your doctor may recommend a treatment other than Herceptin.

Fatigue

You may have fatigue as a side effect of Herceptin. This was commonly reported by people who received the drug in clinical studies. Most people who had this side effect had mild fatigue.

With fatigue, you lack energy even if you get a good night’s sleep.

What you can do

If you have fatigue while receiving Herceptin, talk with your doctor. They may recommend a remedy, such as meditation, yoga, or other exercise. These have shown some ability to treat fatigue caused by breast cancer treatment.

Other ways to help manage fatigue due to Herceptin include:

  • eating a nutritious, balanced diet
  • going to bed at the same time every night and waking up at the same time every morning
  • organizing your day and planning activities for when you have the most energy
  • joining a support group

Depression

Depression is a more common side effect of treatment with Herceptin. This side effect was reported by people who received the drug in clinical studies.

Symptoms of depression can include:

  • loss of interest or pleasure from activities you usually enjoy
  • feelings or thoughts of guilt or worthlessness
  • fatigue
  • sleep problems
  • depressed mood

What you can do

If you feel that you have depression during your Herceptin treatment, talk with your doctor.

A cancer diagnosis can bring on a variety of emotions and may lead to depression in some people. Your doctor can suggest ways to help you manage depression while you’re receiving treatment for cancer.

Allergic reaction

As with most drugs, Herceptin can cause an allergic reaction in some people. This side effect was somewhat rare in clinical studies.

Symptoms can be mild or serious and can include:

  • rash
  • itching
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep receiving Herceptin. But if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Here’s some information about precautions to be mindful of before you start Herceptin treatment.

Boxed warnings

Herceptin has boxed warnings about the following:

  • heart problems
  • lung problems
  • infusion reactions
  • harm to a fetus

A boxed warning is the most serious warning from the FDA.

For details about heart and lung problems and infusion reactions, see “Boxed warnings” in the “Side effect specifics” section above. To learn more about harm to a fetus, see “Pregnancy and breastfeeding while receiving Herceptin” in the “Precautions for Herceptin” section below.

Other precautions

Be sure to talk with your doctor about your health history before you use Herceptin. This drug may not be the right treatment if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Neutropenia caused by chemotherapy: In clinical studies, neutropenia was more likely to be a side effect in people who received Herceptin plus chemotherapy than people who received chemotherapy alone. Before receiving Herceptin, be sure your doctor knows whether chemotherapy has caused neutropenia for you in the past. If it has, you may be more likely to have this side effect from Herceptin.

Allergic reaction: You should not use Herceptin if you’ve ever had an allergic reaction to Herceptin or any of its ingredients. Talk with your doctor about other treatment options that might be better for you.

Alcohol with Herceptin

Alcohol isn’t known to interact with Herceptin. But consuming alcohol could worsen certain side effects of Herceptin or increase your risk of them. Examples of these side effects include:

  • headache
  • diarrhea
  • fluid retention
  • heart problems,* such as high blood pressure or heart failure

Talk with your doctor about how much alcohol, if any, is safe for you to drink while receiving Herceptin.

* Herceptin has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA. To learn more, see “Boxed warnings” in the “Side effect specifics” section above.

Pregnancy and breastfeeding while receiving Herceptin

Here’s some information about pregnancy, breastfeeding, and Herceptin.

Pregnancy

Herceptin should not be used during pregnancy. Be sure to use birth control while using Herceptin and for at least 7 months after the last dose of the drug. Herceptin may harm a fetus, and this could include pregnancy loss. In fact, Herceptin has a boxed warning about this risk. This is the most serious warning from the FDA.

If you can become pregnant, your doctor will have you take a pregnancy test before you start receiving Herceptin. This is to make sure you’re not pregnant when you start treatment.

The manufacturer of Herceptin, Genentech, has a pregnancy monitoring program to gather information on the use of the drug during pregnancy. If you become pregnant during your Herceptin treatment or within 7 months of your last dose, consider calling Genentech at 888-835-2555.

If you’re pregnant or planning a pregnancy, talk with your doctor. They can suggest treatments other than Herceptin.

Breastfeeding

It’s unknown whether it’s safe to breastfeed during Herceptin treatment. It’s also unknown whether the drug is present in human breast milk.

If you’re breastfeeding or thinking about it, talk with your doctor. They can review the risks and benefits of Herceptin treatment and advise you on alternative feeding options for your child.

If you’d like to learn more about Herceptin, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from treatment with the drug.

Mild side effects of Herceptin may last a few days or weeks. But if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

You should also talk with your doctor if you develop serious side effects. For more information, see the “Serious side effects of Herceptin” section above.

Keep in mind that Herceptin is not safe to receive while pregnant. If you become pregnant during your treatment, talk with your doctor immediately.

Other resources

Besides talking with your doctor, you might want to do some research on your own. These articles might help:

  • More information on Herceptin: For details on other aspects of Herceptin, refer to this article.
  • Cost: If you’d like to learn about Herceptin and cost, see this article.
  • Drug comparison: To learn how Herceptin compares with other medications, read the “Herceptin vs. Kadcyla,” “Herceptin vs. Tykerb,” and “Herceptin vs. Herceptin Hylecta” sections of this article.
  • Dosage: For information about the dosage of Herceptin, view this article.
  • A look at your condition: For details on cancer, visit our cancer hub. To learn more about breast cancer, see our list of breast cancer articles and this article about Herceptin for breast cancer. If you’d like more information on stomach cancer, talk with your doctor.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.