What should you know about side effects of immunotherapy for melanoma?

Immunotherapy helps the immune system recognise and attack cancer, but that immune activity can sometimes affect normal tissues. Possible effects include tiredness, itching or rash, diarrhoea, cough, shortness of breath, joint pain, changes in thyroid function, or inflammation of the liver, bowel, lungs or other organs.

Symptoms may begin during treatment or after a dose has finished. Their severity is not reliably shown by how you feel at first, and a mild change can become more serious if it is ignored. The side effect may also have another cause, so the team may use an examination and blood tests to investigate.

Keep a record of new symptoms, their start date and any change after treatment. Contact the oncology team promptly rather than waiting for the next appointment. Do not start steroids, anti-diarrhoea medicines, supplements or other treatments for a suspected immune reaction without advice, because the right response depends on the affected organ and its severity.

Carry your immunotherapy treatment information when seeking care. Tell every clinician that you are receiving immunotherapy, including if you attend another hospital. The team may pause treatment, arrange tests or prescribe treatment to calm inflammation; this does not mean the cancer plan has been abandoned.

Seek urgent medical help for severe breathlessness, chest pain, confusion, fainting, severe weakness, blood in the stool or vomit, yellowing of the skin, severe abdominal pain, uncontrolled diarrhoea, a seizure or a rapidly spreading blistering rash. Contact the treatment team promptly for persistent diarrhoea, new cough, fever, marked thirst, reduced urine, unusual headaches or visual changes.

Which symptoms should I report the same day? Who should I call outside clinic hours? Could my current medicines mask or worsen an immune reaction? What tests will monitor my thyroid, liver, kidneys and other organs, and when can treatment safely resume after a side effect?