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Side effects of biological therapy

Side effects can occur with any type of treatment, 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)
  • the dose
  • how the drug is given
  • the person’s overall health

Side effects can happen any time during, immediately after or a few days or weeks after biological therapy. Most side effects go away when treatment is finished. However, some side effects may continue after treatment is over because it takes time for healthy cells to recover from the effects of biological therapy drugs. Late side effects can occur months or years after treatment. Some side effects may last a long time or be permanent. Many biological therapies do not cause long-term problems.

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

The following are the most common side effects that people tend to experience with biological therapy. Some people may experience all, some or none of these side effects. Others may experience different side effects.

Flu-like symptoms

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

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

These symptoms often occur immediately after treatment but lessen with time. Giving the injection before bedtime and taking other medicines, such as acetaminophen (Tylenol), can help reduce these side effects and allow some people to sleep through them. People should check with their doctor or healthcare team if these symptoms do not go away 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 makes a person feel more tired than usual and can interfere with daily activities and sleep. Fatigue is a common, temporary problem that can occur with certain biological therapy drugs. It is often related to the dose of biological therapy drug given and usually goes along with flu-like symptoms.

Fatigue is often described in younger children as:

  • feeling weak or tired
  • having a blank look
  • feeling sad
  • having difficulty with body movements, such as using their arms and legs or opening their eyes

Fatigue is often described by adolescents as:

  • sleepiness
  • being physically and mentally tired
  • feeling “not themselves”
  • lack of energy

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Swelling, redness or rash at injection site

Many biological therapy drugs are given by injection. The area around the injection site can become swollen or red. A rash can appear shortly after the injection.

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Changes in brain function

Changes in brain function can sometimes occur with biological therapy, including:

  • changes in cognitive functioning, including concentration and reasoning
  • changes in emotions, including depression, irritability and mood swings
  • short-term or long-term memory loss
  • balance and coordination problems

How biological therapy affects mental, emotional and neurological function is not really known. The severity of these changes depends on the amount of drug given. These symptoms will continue as long as the biological therapy is given. Symptoms often disappear after treatment stops. Some people may need medicines to manage these changes.

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Bone marrow suppression

Bone marrow suppression is a condition in which one or more of the main types of blood cells are decreased.

  • A low white blood cell count (neutropenia or leukopenia) increases the risk of infection.
  • A low platelet count (thrombocytopenia) increases the risk of bruising and bleeding.
  • A low red blood cell count (anemia) causes fatigue, paleness and malaisemalaiseA general feeling of discomfort or illness..

Biological therapy may affect the bone marrow’s ability to make blood cells, especially white blood cells and platelets. The person’s blood will be checked regularly to make sure these blood cell levels stay within a normal range. Therapy may have to be stopped for a while if the levels go too low, to allow the number of cells to return to normal.

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Skin changes

Some biological therapy drugs can cause skin changes, including redness, itching, dryness and peeling. These can occur during therapy and for some time afterward. Tell the healthcare team if you experience these skin changes. They can suggest moisturizers and creams and may prescribe medicines to relieve the itchiness.

Lumps (nodules) can develop under the skin at the site of subcutaneous injections. These usually go away after treatment ends. It is important to pick a different site for every injection so that each site has a chance to heal as much as possible before the next injection.

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Sore mouth

A sore mouth (also called stomatitis or oral mucositis) occurs because of biological therapy’s effect on cells inside the mouth. Many drugs can cause a sore mouth. It occurs more often when higher doses of drugs are used. A sore mouth can develop within 2 weeks of starting biological therapy. It quickly improves on its own after treatment is finished.

Painful sores, ulcers or infection can develop in the mouth, throat or gums. 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. Pain medicines or special oral solutions may be needed to relieve pain.

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Bone pain

Bone pain is a common side effect of colony-stimulating factors. The increased production of blood cells in the bone marrow causes more pressure in the middle of the bone. Bone pain usually goes away after the person’s body adjusts to the drug.

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Change in blood pressure

A person’s blood pressure may be lowered or raised depending on the biological therapy drug given. This is not a common side effect. The healthcare team will check your blood pressure, especially when biological therapy first starts. Getting up slowly may help prevent dizziness. Dizziness that occurs when someone is standing should be reported to the doctor.

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Allergic reaction

An allergic reaction (hypersensitivity) can occur when any type of drug is given, but it is a rare side effect of biological therapy drugs. 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 person is closely monitored for allergic reactions, especially when drugs are first given. Medicines and other treatments (such as oxygen therapy) are given if a severe allergic reaction occurs.

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Liver problems

Some biological therapies may cause an increase in certain liver enzymes. Slight increases in these enzymes often do not cause any symptoms and are only detected by routine blood tests. It is not known why biological therapy causes an increase in liver enzymes. Often, the enzyme levels go down as the person’s body adjusts to the drug. They usually return to normal soon after the treatment ends.

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Capillary leak syndrome

Capillary leak syndrome occurs when fluid in the small blood vessels (called capillaries) leak out into the surrounding tissue. Normally, fluid moves back and forth through the vessel walls in a controlled way. But, in capillary leak syndrome, more fluid leaks into the tissue than the tissue can hold. This causes an increase in weight, a drop in blood pressure, increased heart rate, difficulty breathing and kidney problems. Large amounts of fluid can build up in the tissues (edema), organs (effusions) and the abdominal cavity (ascites).

Capillary leak syndrome usually occurs when a biological therapy drug (especially high-dose interleukin) is first given, and it can happen quickly. The healthcare team watches closely for any signs of capillary leak syndrome. They will give medicines and other treatments, such as oxygen therapy, if this side effect occurs.

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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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