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Side effects of immunotherapy

Like all treatments, checkpoint inhibitors can cause side effects. These are sometimes called immune-related adverse effects (IRAEs).

Immunotherapy side effects are different to the side effects of other cancer treatments and need to be managed differently.

When to expect side effects

You may have side effects within days of starting treatment, but more commonly they occur several weeks or months after starting treatment. In some rare cases, new side effects can appear months after finishing treatment.

Most people have mild side effects. Side effects are likely to be more severe if you are having higher doses or a combination of immunotherapy drugs, or if you are having immunotherapy with other cancer treatments. 

Common and rare side effects of immunotherapy

Checkpoint inhibitors trigger an immune response that can lead to redness, swelling or pain (inflammation) anywhere in the body. Side effects will depend on which part of the body becomes inflamed. Examples of common and rare side effects are below. The side effects you have will depend on the drug and how your body responds. While some people have serious side effects, others have just one or two mild side effects. 

Fatigue – tiredness that does not go away with rest, caused by inflammation throughout your body

Dry eyes – could be inflammation of the eyes or tear glands

Changes in weight and body temperature – could be inflammation causing the thyroid to work too fast (hyperthyroidism, leading to weight loss and feeling warm) or too slow (hypothyroidism, leading to weight gain and feeling cold)

Skin rash and itching – could be dermatitis, which makes skin red, bumpy and itchy

Diarrhoea, abdominal pain and bloating – could be inflammation of the bowel (colitis)

Pain in the joints – could be inflammation of the joints (arthralgia), especially if you already have arthritis or a similar condition

Headache or blurred vision – could be inflammation of the pituitary gland (hypophysitis) or the membranes around the brain and spinal cord (meningitis)

Breathlessness, coughing, fainting or chest pain – could be a lung or heart problem – rare but serious

Yellowing of the eyes, severe abdominal pain and dark urine – could be inflammation of the liver (hepatitis)

Excessive thirst or urination – could be inflammation of the pancreas affecting the production of insulin

Reduced urination or blood in the urine – could indicate problems in the kidneys – very rare but serious

Muscle pain – could be inflammation of the muscles (myositis)

Confusion, seizures – could be nerve problems – very rare but serious

Other rare side effects can occur, and some side effects can be life-threatening. Let your treatment team know about any new or worsening side effects during or after treatment. Do not try to treat side effects yourself. Most immunotherapy side effects can be managed and reversed if they are reported early.

Managing side effects

Because immunotherapy works differently from other cancer treatments, it’s important to work closely with your treatment team to monitor any side effects and how the cancer responds.

Before starting immunotherapy, discuss the potential side effects with your cancer specialist. Ask which side effects to watch out for or report, who to report them to, and who to contact after hours. You can read about the side effects of specific checkpoint inhibitors at eviq.org.au.

Before treatment begins, you will usually have some tests to check that you are well enough to have immunotherapy. Throughout treatment, the team will regularly test your blood and ask you questions to check for early signs of side effects. New side effects can appear months after having immunotherapy, so ask your cancer specialist how long you need to keep watching for side effects.

Reporting side effects

Side effects can be better managed if reported early, so it is important to let your cancer care team know about new or worsening symptoms, even if they seem minor or you’re not sure if they are related to your treatment. If left untreated, side effects can become serious and may even be life-threatening.

Sometimes it can be tricky to know whether your symptoms are related to the cancer or the treatment. Make sure to discuss this with your cancer care team.

Because immunotherapy is a newer cancer treatment, general practitioners (GPs) and other health professionals may not yet be familiar with the side effects. Your team may give you a card with information about your immunotherapy treatment and potential side effects. You can show this card to other health professionals you see and ask them to consult with your cancer specialist. Do not start any new medicines, including anti-inflammatory steroids, herbal therapies or over-the-counter medicines, until your cancer specialist has been consulted. If you become unwell, even years later, it is important to tell any health professionals you see that you have had immunotherapy.

Treating side effects

Side effects are graded on a scale of 1–4. Your doctor will tell you how to manage mild to moderate side effects (grades 1–2). For example, you may be given a moisturising cream to treat a skin rash. Moderate to severe side effects (grades 2–4) are often treated with steroid tablets, such as prednisolone. In some cases of severe side effects (grades 3–4), people may need to stay in hospital and/or have intravenous steroids or other medicines, and immunotherapy may be stopped until the side effects are better controlled.

If side effects become too severe, you may have to stop immunotherapy permanently. In this case, the immunotherapy that you have already received may have “trained” your immune system to recognise cancer cells, so you may continue to benefit.

Although there is a risk of severe side effects, it may be reassuring to know that many people experience only mild side effects. 

If you have had immunotherapy, it is important to check with your cancer specialist before having vaccinations, including for flu or COVID-19. 

Featured resource

Understanding Immunotherapy

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This information is reviewed by

This information was last reviewed July 2021 by the following expert content reviewers: Dr Jenny Lee, Medical Oncologist, Chris O’Brien Lifehouse, NSW; Prof Michael Boyer, Medical Oncologist and Chief Clinical Officer, Lung and Thoracic Cancer, Chris O’Brien Lifehouse, and Central Clinical School, The University of Sydney, NSW; A/Prof Christine Carrington, Senior Consultant Pharmacist Cancer Services, Princess Alexandra Hospital, QLD; Dr Inês Pires da Silva, Medical Oncology Fellow, Melanoma Institute Australia and Westmead and Blacktown hospitals, NSW; Sandra Donaldson, 13 11 20 Consultant, Cancer Council WA; Sherry Gilbert, Consumer; Marilyn Nelson, Consumer; Julie Teraci, Skin and Melanoma Cancer Nurse Coordinator, WA Cancer and Palliative Care Network, North Metropolitan Health Service, WA; Helen Westman, Lung Cancer Nurse Coordinator, Cancer and Palliative Care Network, Royal North Shore Hospital, NSW.