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Potential side effects of biological therapy for breast cancer

Side effects can occur with any type of treatment for breast cancer, but not everyone has them or experiences them in the same way. Side effects of biological therapy will depend mainly on the:

  • type of drug(s)
  • dose
  • woman’s overall health

Side effects can happen any time during biological therapy. Some may happen during, immediately after, or a few days or weeks after biological therapy. Most side effects go away after biological therapy is over. Late side effects can occur months or years after biological therapy. Some side effects may last a long time or be permanent.

It is important to report side effects to the healthcare team. Doctors may also grade (measure) how severe certain side effects are. Sometimes biological therapy needs to be adjusted if side effects are severe.

Only the main side effects shared by most biological therapies used for breast cancer are mentioned here. For more detailed information on specific drugs, go to sources of drug information.

Headache

A headache is one of the most common side effects of biological therapy for breast cancer. The healthcare team may recommend mild pain medications, such as acetaminophen (Tylenol), to help relieve a headache. Any headache that does not improve with medication, or dizziness with the headache, should be reported to the doctor.

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Diarrhea

Diarrhea is an increase in the number and looseness of stools. It is a common side effect biological therapy for breast cancer.

Many factors increase the risk of diarrhea, including the type and dose of biological therapy used. Diarrhea is often worse when combinations of drugs are given. Diarrhea occurs soon after biological therapy starts and can continue for up to 2 weeks after treatment has ended.

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Nausea and vomiting

Not all biological therapy drugs used to treat breast cancer cause nausea and vomiting, but many do. Individual drugs vary in their effects, but nausea and vomiting are more likely when combinations of drugs are given.

Nausea and vomiting can occur within the first few hours after biological therapy drugs are given and usually last about 24 hours. However, delayed nausea and vomiting may continue for a few days after treatment. Some women may have anticipatory nausea after having a few treatments, where they feel nauseated even before treatment is given because they expect to be sick.

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Skin rash

A skin rash can occur with several biological therapies used for breast cancer. The skin may be red, dry and itchy.

Using a moisturizer recommended by the healthcare team can help relieve the rash. Protect the skin by staying out of the sun. If going outside, use sunscreen and wear a hat, long-sleeved shirts and pants.

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Flu-like symptoms

Flu-like symptoms are a common side effect of several biological therapies used for breast cancer. Symptoms include:

  • fever
  • chills
  • muscle and joint aches or pain
  • nausea
  • vomiting
  • loss of appetite (anorexia)

These symptoms often occur immediately following treatment but lessen with time. Giving the injection before bedtime and taking other medications, such as acetaminophen (Tylenol), can help reduce these side effects and allow some people to sleep through them. Women should check with their doctor or healthcare team if these symptoms persist or are bothersome. Flu-like symptoms usually go away with continued therapy, once the body gets used to the drug.

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Fatigue

Fatigue is a common, temporary problem that can occur with certain biological therapy drugs used to treat breast cancer. It is often related to the dose of biological therapy drug being given and usually goes along with flu-like symptoms.

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Allergic reaction

An allergic reaction (hypersensitivity) can occur when any type of drug is given, but it is generally a rare side effect of biological therapy drugs used to treat breast cancer. Signs of an allergic reaction can include:

  • difficulty breathing
  • wheezing
  • coughing
  • skin rash or hives (may be itchy)

A severe allergic reaction (anaphylaxis) may also occur. The woman is closely monitored for allergic reactions, especially when drugs are first given. Medications and other treatments (such as oxygen therapy) are given if a severe allergic reaction occurs.

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Constipation

Constipation is a decrease in the normal number of bowel movements. The stools become hard, dry and difficult to pass. Many factors increase the risk of constipation, including the type of biological therapy drug used, medications given to relieve nausea and vomiting, and decreased fluid intake. Constipation usually occurs 3–7 days after the biological therapy drug is given.

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Muscle and joint pain

Some biological therapy drugs used for breast cancer can cause muscle and joint pain. It is often related to the dose of biological therapy drug being given and often goes along with flu-like symptoms. The healthcare team may suggest a mild pain medication, such as acetaminophen (Tylenol), to help relieve the pain, along with rest. Light exercise may also help improve pain and stiffness.

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Swelling, redness or rash at injection site

Some biological therapy drugs used to treat breast cancer are given by injection. The area around the injection site can become swollen or red, or a rash can appear shortly after the injection.

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Loss of appetite

Nausea and vomiting, fatigue or a buildup of waste products as cancer cells die from treatment can cause loss of appetite. Some women lose interest in food completely and don’t eat, even though they know they need to. This can lead to weight loss and malnutrition. Maintaining good nutrition during and after biological therapy is important to help recover from treatment.

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Sore mouth

A sore mouth (also called stomatitis or oral mucositis) may be a side effect of some biological therapies used to treat breast cancer. It occurs more often when higher doses of drugs are used.

Painful mouth sores, ulcers in the mouth and mouth infections can also develop. Thorough, regular mouth care can help prevent a sore mouth and reduce infection. The healthcare team will give instructions about how often to clean and rinse the mouth and what to use. Medicines or special oral solutions may be needed to relieve pain.

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Change in blood pressure

A woman’s blood pressure may be lowered or raised depending on the biological therapy drug used. This is not a common side effect. Blood pressure is monitored, especially when the drug is first started. Getting up slowly may help prevent dizziness. Dizziness that occurs when a woman is standing should be reported to the doctor.

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Heart damage

Both trastuzumab (Herceptin) – especially when combined with anthracycline drugs – and lapatinib (Tykerb) may cause heart damage, including congestive heart failure and irregular heart beat.

Heart function tests are done before treatment starts and then regularly during treatment with these biological therapy drugs:

Heart damage caused by trastuzumab may be reversible after treatment is stopped. Heart damage caused by anthracycline drugs is usually permanent.

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Note: Other side effects may occur. For more detailed information on specific drugs, go to sources of drug information.

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