Side Effects of Immunotherapy

Approved by the Cancer.Net Editorial Board, 05/2019

This content was last updated 1 November 2021.

Immunotherapy is a type of cancer treatment. It uses the body's natural defenses to fight cancer by improving your immune system’s ability to attack cancer cells.

There are many types of immunotherapy. Side effects for 2 types of immunotherapy are discussed on this page: immune checkpoint inhibitors and chimeric antigen receptor (CAR) T-cell therapy.

Side effects can appear as signs, such as changes in something measured like blood pressure or lab tests, and as symptoms, which are changes that you can see or feel in your body. Additional signs and symptoms that can arise from immune checkpoint inhibitors, CAR T-cells, and other types of immunotherapies, such as viral and cellular immune therapies, are also listed further down this page.

Learn more about the different types of immunotherapy

Why does immunotherapy cause side effects?

Immunotherapy treats many types of cancer effectively. But 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 type of immunotherapy, the type of cancer, 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 events.” These may occur 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, and the potential side effects of your immunotherapy.

Are there ways to prevent or treat these side effects?

Your health care team can help you prevent or relieve many 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, different, or worsening health problems as soon as possible. This includes problems that 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. Early recognition of symptoms and either pausing immunotherapy or treating side effects can 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. For mild side effects, your treatment will likely continue and you will be monitored for changes in your symptoms. If you have moderate or severe side effects, your doctor may pause the treatment and they may prescribe a type of medication called a corticosteroid 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 regimen, especially if you were given a combination of medications. If side effects do not go away or get worse, your doctor may 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 instance, 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 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.

What are common immunotherapy side effects and syndromes?

The most common side effects depend on which kind of immunotherapy you are receiving. 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.

Immune checkpoint inhibitors

Immune checkpoint inhibitors include medications that change the interactions between immune cells and cancer cells using molecules called PD-1, PD-L1, CTLA-4, and others. They include drugs such as atezolizumab (Tecentriq), avelumab (Bavencio), cemiplimab (Libtayo), dostarlimab (Jemperli), durvalumab (Imfinzi), ipilimumab (Yervoy), nivolumab (Opdivo), and pembrolizumab (Keytruda). Side effects from immune checkpoint inhibitors are usually caused by the immune system attacking normal body parts, the same way it attacks 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 tract. Problems with the gastrointestinal tract are some of the most common side effects related to immune checkpoint inhibitors. These include inflammation of the colon, which is called colitis, and 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 immune checkpoint inhibitors. This is usually first noticed by your health-care provider when they review your lab results.

  • 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 a vital part of the endocrine system, and it may be triggered to become either more or less productive by immune checkpoint inhibitor treatment. There are rare cases where people develop a type of diabetes related to immune checkpoint inhibitors, called checkpoint inhibitor-associated diabetes (CIADM), which is similar to type 1 diabetes.

  • Heart and blood vessels. Immunotherapy may affect the heart and blood vessels. These side effects are rare but 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 in the future. Patients of reproductive age should take steps to avoid conception during treatment and for at least 5 months after treatment ends.

  • Reactions during the infusion. When an immunotherapy drug is given to the patient 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.

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. This type of immunotherapy includes medications like axicabtagene ciloleucel (Yescarta), brexucabtagene autoleucel (Tecartus), idecabtagene vicleucel (Abecma), lisocabtagene maraleucel (Breyanzi), and 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 a protein called a cytokine into the blood. This process can send the immune system into overdrive, leading to a syndrome called 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, and 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 and behavioral changes; inability to speak or understand speech, which is called aphasia; problems with attention, thinking, and memory; weakness in the muscles; tremors; muscle jerks and twitching; headache; and seizures. Treatment 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 general feeling of discomfort.

  • Bone marrow suppression. CAR T-cell therapy may lower the function of your bone marrow, the body’s factory for your blood cells. This can lower the numbers 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 effect 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 of 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.

Additional signs and symptoms of side effects from different types of immunotherapies

  • 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, blisters

  • Yellow skin or eyes

  • 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

This is not a complete list of the signs and symptoms that may affect someone taking immunotherapy. 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. Also ask who to contact and what you should do if you have unexpected side effects. Learn more about when to call the doctor during cancer treatment.

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

Coping with side effects of immunotherapy

Everyone's experience 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. There can also be emotional side effects, and seeking out mental health support to help with anxiety or 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.

And, continue talking with the 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.

Questions to ask the health care team

These questions may be helpful to ask members of your health care team if immunotherapy is recommended as a part of your treatment plan. This list is provided as suggestions. You do not need to ask all of these questions. Focus on the ones that are most important to you in learning about your cancer treatment.

  • 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 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.