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Immune-Related Side Effects of Immunotherapy: What to Watch For
By Dr. Gajendra Kumar Himanshu
Immune-related side effects occur when the immune system is activated by cancer treatment and begins attacking healthy tissues along with cancer cells. They can affect the skin, colon, liver, lungs, thyroid, heart, kidneys or nervous system. They can range from mild to serious, so it is important to report any new symptom to your oncology team quickly.
In this blog, we discuss the immune-related side effects of immunotherapy, why they happen and what symptoms patients should look out for during and after treatment. We cover common organ-related reactions, warning signs that should be treated as an emergency, how doctors monitor for these problems and how immune-related side effects are managed.
Why It Is Important to Know the Side Effects of Immunotherapy
Immunotherapy helps the immune system recognise and fight cancer cells. Immune checkpoint inhibitors are increasingly used to treat many cancers, including lung, breast, bladder, kidney, liver, cervical and several others. However, the stronger immune response can sometimes harm healthy organs and tissues.
These side effects are called immune-related adverse events, or irAEs. They may occur during treatment and, in some cases, even after treatment has ended. Some are mild and easy to treat, while others can become serious or life-threatening if they are not treated promptly.
Patients should not assume that a new symptom is simply a normal part of cancer treatment. Reporting changes early gives doctors a better chance of identifying the cause and starting the right treatment.
What Are the Most Common Immune-Related Side Effects?
Symptoms differ depending on the organ or body system involved. Some reactions happen more often than others.
Skin Problems
Skin reactions are among the more frequent side effects of immune checkpoint inhibitors. Patients may develop a rash, itching, redness or other skin changes. More serious reactions can include blistering or sores.
Any new or worsening rash should be reported to the treatment team. This is particularly important for a rapidly spreading rash, or one that occurs with discomfort, blistering or other symptoms.
Digestive Problems
Colitis is inflammation of the intestine that may cause diarrhoea and abdominal pain. Dark or bloody stools can indicate more severe inflammation of the colon and need medical attention as soon as possible.
Patients should tell their oncology team about any new diarrhoea rather than managing it themselves, because it may be caused by an infection, another medicine or immune-related inflammation.
Liver Inflammation
Immunotherapy can cause hepatitis, or inflammation of the liver. Compared with some other side effects, liver inflammation may cause few symptoms at first and may be detected initially through abnormal liver blood tests. Some people may experience tiredness, nausea, abdominal discomfort, dark urine, yellowing of the skin or eyes, or increased bruising.
This is why regular blood tests and ongoing monitoring are important.
Lung Inflammation
Pneumonitis is inflammation of the lungs and can cause a persistent cough, shortness of breath or chest discomfort. It is less common, but it can be dangerous or life-threatening.
Breathing symptoms should never be ignored, particularly in patients receiving immunotherapy.
Hormonal Side Effects
Inflammation caused by the immune response can affect organs that make hormones, such as the thyroid, pituitary and adrenal glands. The symptoms can be mistaken for ordinary tiredness or other effects of treatment.
Thyroid Problems
Inflammation of the thyroid may first make the gland overactive and then underactive. Common symptoms include weight changes, sweating, sensitivity to heat or cold, constipation, dry skin, weakness or tiredness.
Doctors frequently check thyroid hormone levels during immunotherapy so that problems can be picked up before they become serious.
Pituitary and Adrenal Problems
Inflammation of the pituitary gland can cause headaches and fatigue. Inflammation of the adrenal gland can cause weakness, loss of appetite, weight loss or abdominal pain. These conditions may need hormone replacement and careful medical supervision.
Less Common but More Serious Side Effects
Immunotherapy can trigger inflammatory reactions in the heart, kidneys, pancreas and nervous system, although these are rare.
Affected Area | Possible Immune-Related Effect | Symptoms to Watch For |
|---|---|---|
Heart | Myocarditis, or inflammation of the heart muscle | Chest pain, shortness of breath, irregular heart rhythms or reduced heart function |
Kidneys | Nephritis, or inflammation of the kidneys | Reduced urine output or blood in the urine |
Nervous system | Rare neurological inflammation or other immune-related effects | Numbness, weakness, confusion, seizures or other changes in nerve or brain function |
These side effects are less common but can be serious. New or worsening symptoms should be medically evaluated promptly.
When Should You Call Your Doctor?
Patients should report new or worsening symptoms rather than waiting until the next appointment. Seek urgent medical attention for symptoms such as severe diarrhoea, difficulty breathing, chest pain, yellowing of the skin or eyes, extreme weakness, confusion, seizures or a marked reduction in urine output.
How urgent the situation is depends on the symptom and its severity. Your oncology team should explain which symptoms are safe to monitor at home and which are signs of an emergency.
How Are Immune-Related Side Effects Diagnosed?
Doctors first review the symptoms, the medicines being used and when they were given. Blood tests, urine tests, imaging or other investigations may be ordered to identify which organ is affected and to rule out other causes such as infection or cancer progression.
Regular monitoring during immunotherapy is important, because several immune-related problems, particularly liver and hormonal ones, may cause few symptoms at first.
How Are Immune-Related Side Effects Managed?
Treatment depends on the organ involved and the severity of the reaction. Doctors may temporarily stop immunotherapy and prescribe corticosteroids or other medicines to calm down an overactive immune response. Serious reactions may require specialist treatment or admission to hospital.
Patients should not stop their prescribed immunotherapy or start steroids on their own. The treating oncology team should decide whether to pause, restart or permanently stop treatment.
Can Side Effects Appear After Immunotherapy Has Finished?
Yes. Immune-related side effects can arise during treatment and can also appear after treatment has been completed. This is why patients should continue to mention their history of immunotherapy when seeking medical care, even if the last dose was some time ago.
For more information regarding immunotherapy, visit the National Cancer Institute.
Consult Today
If you are receiving immunotherapy and develop a new or worsening symptom, speak to your oncology team early so they can assess whether it is treatment-related and needs prompt attention. At Oncare Cancer Hospital, patients can discuss the side effects of immunotherapy with the specialist team and receive advice on monitoring, investigations and treatment based on their particular cancer and therapy.
Disclaimer
This blog is for educational purposes only and does not replace professional medical advice, diagnosis or treatment. Any new or persistent symptom during immunotherapy requires individual evaluation to determine its cause. Consult a qualified doctor for personalised advice.
Frequently Asked Questions
Immune-related side effects are problems that develop when the activated immune system starts attacking healthy tissues. They may affect the skin, colon, liver, lungs, thyroid, heart, kidneys and nervous system.
Common side effects include rash, itching, diarrhoea and fatigue. However, because immunotherapy can cause inflammation in many organs, symptoms vary from person to person.
Most can be managed if they are identified early. However, some reactions, such as severe pneumonitis, myocarditis, hepatitis or inflammation affecting the brain, can be serious or life-threatening.
Yes, this can happen. Immune-related side effects may occur during treatment or after immunotherapy has been stopped. If new problems arise, patients should tell their healthcare providers about their previous immunotherapy.
Written and Verified by:
Dr. Gajendra Kumar Himanshu Exp: 10 Yr
Medical Officer
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