Side Effects of Immunotherapy

Approved by the Cancer.Net Editorial Board, 05/2022

Immunotherapy is a type of cancer treatment. It uses substances made by the body or in a laboratory to boost the immune system and help the body find and destroy cancer cells.

This article will help you understand the possible side effects for different types of immunotherapy, including immune checkpoint inhibitors and chimeric antigen receptor (CAR) T-cell therapy.

Side effects can appear as signs or symptoms. Signs are changes that can be measured, like blood pressure or body temperature. Symptoms are changes that you can feel in your body.

Learn more about the basics of immunotherapy and how it works.

Why does immunotherapy cause side effects?

Immunotherapy treats many types of cancer effectively. Like other cancer treatments, they are powerful medications that can cause changes within the body or to how you feel, called side effects. These side effects are different for everyone. They depend on the specific type of immunotherapy you receive, the type of cancer you have, its location, your general health, and other factors.

Immunotherapy may also cause the immune system to attack healthy cells. This can cause side effects, also called "immune-related adverse effects." These may happen at any time during treatment or sometimes even after stopping immunotherapy.

Different types of immunotherapy cause different side effects. That's why it is important to talk with your doctor about the type of immunotherapy used for your cancer, the goals of treatment, the potential side effects of your immunotherapy, and signs and symptoms to watch for.

Are there ways to prevent or treat immunotherapy side effects?

Your health care team can help you prevent or relieve many treatment side effects. Preventing and treating side effects is an important part of your overall cancer treatment. This is called palliative care or supportive care.

Before immunotherapy begins, ask your health care team what side effects are likely. During treatment, let them know about any new or worsening health problems as soon as possible. This includes health problems you may not think are serious or caused by immunotherapy. It is easier for your health care team to effectively treat a side effect when the problem first appears. Knowing what to watch for and early recognition of symptoms is important. Your doctor may recommend pausing immunotherapy or treating side effects to prevent them from becoming severe.

Side effects of immunotherapy can be mild, moderate, or even life-threatening. Doctors grade side effects on a scale of 1 to 4, with 1 being mild and 4 being the most severe. How your doctor treats your side effects will depend on how severe they are.

Mild side effects. For mild side effects, your treatment will likely continue and you will be monitored for changes in your symptoms.

Moderate to severe side effects. Your doctor may pause the treatment and they may prescribe a type of medication called a corticosteroid (like prednisone or others) to calm the immune system. Sometimes, other medications may also be given after a corticosteroid. If the side effects are relieved, your doctor may try to start immunotherapy again or adjust your treatment plan, especially if you were given a combination of medications. If side effects do not go away or get worse, your doctor may decide to stop treatment with immunotherapy.

If a side effect becomes severe, you may need to get medical care at a place not familiar with your cancer treatment. For example, you may need to go to an emergency room. Be sure to tell the health care team there that you are on immunotherapy. If possible, give them the name of the drug, your oncologist, and the cancer center where you receive immunotherapy. Keep this information in your wallet or phone in case you need it quickly. Download and print Cancer.Net's foldable wallet card to organize this information. You can also download Cancer.Net's mobile app to keep track of this information.

The most common side effects depend on what kind of immunotherapy you are receiving. This article will describe common side effects caused by:

Always let your cancer care team know when you experience a new or worsening medical problem during immunotherapy, even if those symptoms are not listed below.

What are the most common side effects of immune checkpoint inhibitors?

Immune checkpoint inhibitors are immunotherapy treatments that prevent cancer cells from blocking the immune system. Common pathways that these inhibitors affect are the PD-1/PD-L1 and CTLA-4 pathways. Examples of immune checkpoint inhibitors for cancer include:

  • Atezolizumab (Tecentriq)

  • Avelumab (Bavencio)

  • Cemiplimab (Libtayo)

  • Dostarlimab (Jemperli)

  • Durvalumab (Imfinzi)

  • Ipilimumab (Yervoy)

  • Nivolumab (Opdivo)

  • Pembrolizumab (Keytruda)

Side effects from immune checkpoint inhibitors are usually caused by the immune system attacking normal body parts in addition to cancer cells. This is a process called inflammation. Side effects of immune checkpoint inhibitors may affect the following parts of the body.

Skin. Skin problems, like rash and itching, are most common in people with melanoma and non-small cell lung cancer, but people with any kind of cancer can develop skin problems related to treatment with an immune checkpoint inhibitor.

Gastrointestinal (GI) tract. Problems with the GI tract, also called the digestive tract, are some of the most common side effects related to immune checkpoint inhibitors. These include inflammation of the colon, which is called colitis, resulting most often in diarrhea. Less common side effects include swallowing problems, nausea and vomiting, and pain in the upper abdomen.

Muscles and skeleton. Problems with the muscles, joints, and bones may occur in people receiving immune checkpoint inhibitors. This can result in arthritis-type pain, swelling in joints, and muscle cramping.

Kidneys. Damage to the kidneys or kidney failure is uncommon, but it sometimes does occur in people receiving an immune checkpoint inhibitor. This is usually first noticed by your health care provider when they review your lab results from blood/urine tests.

Nerves. Immune checkpoint inhibitors may cause nervous system side effects that impact your brain, senses, or even movements. There can be pain and sensation changes called neuropathy. These are rare but possibly severe side effects.

Blood. Immunotherapy may cause lowered blood counts, which may lead to bleeding, anemia, and other problems.

Lungs. Immune checkpoint inhibitors may cause pneumonitis, which is inflammation of the lungs that can cause a cough or trouble breathing. Pneumonitis is uncommon but may be serious.

Endocrine system. The endocrine system controls the hormones that help the body regulate many important functions, like blood pressure, energy, and the ability to respond to stresses like infections and injuries. The thyroid gland is an important part of the endocrine system. It may be triggered to become either more or less productive by immune checkpoint inhibitor treatment. There are rare cases where people can develop a type of diabetes due to the effect of immune checkpoint inhibitors on the pancreas, called checkpoint inhibitor-associated diabetes (CIADM), which is similar to type 1 diabetes. The adrenal gland is another part of the endocrine system. Immune checkpoint inhibitors can cause adrenal insufficiency, where the adrenal glands stop producing normal hormones to keep up the blood sugar and regulate electrolytes. Treatments for endocrine disorders from the above organs usually involve replacement of the hormone that is low (thyroid hormone, insulin, or adrenal hormones like mineralocorticoids).

Heart and blood vessels. Immunotherapy may affect the heart and blood vessels. These side effects are rare, but they are often very serious and can be life-threatening.

Eyes. Treatment with immune checkpoint inhibitors may cause inflammation of the tissues of the eyes. These side effects are uncommon overall, but may be more common among people who receive a combination of immune checkpoint inhibitors.

Reproductive organs. Immunotherapy may affect fertility, which is the ability to conceive a child. Patients of reproductive age should take steps to avoid conception during treatment and for at least 5 months after treatment ends; talk with your doctor for specific guidance for you.

Reactions during the infusion. When an immunotherapy drug is given through a vein, it is called an infusion. People receiving immune checkpoint inhibitors usually do not have a reaction when the infusion is given. If an infusion reaction does happen, the symptoms are often mild and go away on their own. There can occasionally be more severe cases that require adjusting the speed of the infusion, giving medications for pain or other symptoms, or pausing treatment.

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What are the most common side effects of CAR T-cell therapy?

CAR T-cell therapy is a type of immunotherapy that returns adjusted immune cells back into the body to find and destroy cancer cells. Examples of CAR T-cell therapy include:

  • Axicabtagene ciloleucel (Yescarta)

  • Brexucabtagene autoleucel (Tecartus)

  • Idecabtagene vicleucel (Abecma)

  • Lisocabtagene maraleucel (Breyanzi)

  • Tisagenlecleucel (Kymriah)

The most common side effects related to CAR T-cell therapy are described below and result from immune system changes that commonly involve more than 1 body part.

Cytokine release syndrome (CRS). CAR T cells release proteins called cytokines into the blood. This process can send the immune system into overdrive, leading to a syndrome called cytokine release syndrome or CRS. It may show up between 2 and 21 days after treatment begins. Some cases can be serious and cause problems with many organs in the body, requiring medical treatment. A medication called tocilizumab (Actemra) and a steroid may be given. The symptoms of CRS include:

  • Fever

  • Fast heartbeat

  • Nausea

  • Headache

  • Rash

  • Shortness of breath

  • Low blood pressure

If you are receiving CAR T-cell therapy and experience the symptoms of CRS, contact your health care team right away.

Immune effector cell-associated neurotoxicity syndrome (ICANS). ICANS is a syndrome that affects a person's nervous system. It is the second most common side effect of CAR T-cell therapy. ICANS can cause many symptoms, including:

  • Confusion

  • Behavioral changes

  • Inability to speak or understand speech, which is called aphasia

  • Attention, thinking, and memory problems

  • Muscle weakness

  • Muscle jerks and twitching

  • Headache

  • Seizures

Treatment for ICANS includes corticosteroids and supportive care.

Infections. Infections are common after CAR T-cell therapy. They most often happen soon after the infusion because infection-fighting immune cells may be weakened. Symptoms of infection include fever, nausea, fatigue, headache, weakness, and a general feeling of discomfort.

Bone marrow suppression. CAR T-cell therapy may lower the function of your bone marrow, the body's factory for blood cells. This can lower the number of cells produced and released by your bone marrow, resulting in anemia, thrombocytopenia, leukopenia, and neutropenia.

Hemophagocytic lymphohistiocytosis (HLH). In HLH, immune cells called histiocytes and white blood cells build up in the skin, spleen, and liver and destroy other blood cells. This is an uncommon side effects of CAR T-cell therapy. Signs and symptoms are very similar to those of infections (see above).

B-cell aplasia. B cells, also called B lymphocytes, are immune cells in the body. Sometimes CAR T cells will attack healthy B cells, resulting in low numbers of B cells in the body. When this happens, it is called B-cell aplasia. This increases the risk for infections (see above).

Disseminated intravascular coagulation (DIC). CAR T-cell therapy may affect the proteins of the blood that control the thickness and thinness of your blood. This can result in bleeding and/or clotting problems and can be serious.

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What are the most common side effects of other types of immunotherapy?

Below you'll find a list of some of the most common signs and symptoms that may affect someone taking immunotherapy. This is not a complete list. Talk with your doctor about what you should watch for based on the specific medications you are prescribed.

Many side effects and their related symptoms will go away on their own or can be treated effectively over time. However, there are some that can be very serious and need medical attention right away. Talk with your health care team about which side effects you can expect and how to manage them.

  • Cough

  • Breathing problems

  • Blood in urine or dark urine

  • Pain, swelling, or weakness in muscles or joints

  • Stiff neck

  • Swollen lymph nodes

  • Diarrhea

  • Constipation

  • Pain

  • Enlarged spleen or liver

  • Bleeding or bruising easily

  • Sweating more

  • Feeling faint or passing out

  • Headaches

  • Confusion

  • Difficulty concentrating

  • Rash, itching, and blisters

  • Yellow skin or eyes, called jaundice

  • Numbness or tingling

  • Cold hands and feet

  • Trouble walking

  • Seizures

  • Fast heartbeat

  • More sensitive to light

  • Weight gain or weight loss

  • Changes to the eyes, such as dryness or redness

  • Changes in vision, such as blurry or double vision

  • Hair loss or extra hair growth

  • Swelling

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Coping with side effects of immunotherapy

Everyone's experiences with immunotherapy is different. Side effects vary from person to person, even when given the same type of treatment. Before your treatment, ask your health care team which physical side effects are possible and what to watch for. You may also experience emotional side effects. Seeking out mental health support to help with anxiety and stress is important.

Ask your health care team about ways to take care of yourself during and after the treatment period, including getting enough rest, eating well, and staying hydrated.

Continue talking with the health care team during and after treatment. Always tell your health care team when side effects first appear, worsen, or continue. That will allow your health care team to help you feel better as quickly as possible.

What care is needed after immunotherapy ends?

It is important to continue getting care for side effects after immunotherapy ends. Many side effects will go away when you finish treatment. But some effects can last beyond the treatment period. Other effects may appear months or years later. Your health care team can help you watch for and manage late or long-term side effects.

Work with your doctor to create a survivorship care plan after you finish treatment with immunotherapy. This is an important tool to help you watch for new or worsening side effects in the future.

Questions to ask the health care team

Consider asking your health care team these questions if immunotherapy is recommended as a part of your cancer treatment plan.

  • What side effects can I expect from the type of immunotherapy you are recommending for me? When will they likely begin?

  • How can these side effects be managed?

  • Who should I tell when a side effect appears or gets worse?

  • Are there specific side effects I should tell the health care team about right away?

  • What is the best way to contact my health care team about side effects? What about after hours or on weekends?

  • What are the potential long-term effects of this type of immunotherapy?

  • Could this treatment affect my fertility? Should I talk with a fertility specialist before treatment begins?

  • Could this treatment affect my sex life? Do I need to take steps to prevent conception during and after my treatment?

The information in this article is based on ASCO recommendations on managing side effects related to treatment with immune checkpoint inhibitors and CAR T-cell therapy. Note that these links take you to a different ASCO website.

Related Resources

What You Need to Know About Immunotherapy Side Effects

What It’s Like Taking Immunotherapy to Treat Cancer

How Does CAR-T Cell Therapy Work to Treat Cancer

Tumor-Agnostic Treatment for Cancer: An Expert Perspective

ASCO Answers Fact Sheet: Understanding Immunotherapy (PDF)

More Information

National Cancer Institute: Immunotherapy to Treat Cancer

National Comprehensive Cancer Network: Understanding Immunotherapy Side Effects (PDF)

ASCO answers; Side Effects of Immunotherapy

Download ASCO's free 1-page (front and back) fact sheet on Side Effects of Immunotherapy. This printable PDF provides an overview of side effects which may arise from immunotherapy, and how they are treated. The back side includes a symptom tracker for you to fill out with your health care team. Order printed copies of this fact sheet from the ASCO Store.