Nursing care
Immune checkpoint inhibitors: colitis, pneumonitis, endocrine and skin toxicities
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated October 2026
Short answer
Immune checkpoint inhibitors such as pembrolizumab release the brakes on T cells so they attack cancer, but the activated immune system can inflame any organ. Colitis, pneumonitis, hepatitis, thyroid, adrenal and pituitary problems, type 1 diabetes and serious skin reactions can appear at any time, even after treatment ends. Nurses teach patients to report new symptoms early.
Why immunotherapy toxicity is different
Checkpoint proteins such as PD-1 normally restrain T cells and prevent autoimmunity. Tumours exploit this pathway to hide. Antibodies like pembrolizumab block the restraint, allowing T cells to attack cancer cells. The trade-off is immune-mediated inflammation in healthy tissue, so the toxicities look like autoimmune diseases rather than the cell-killing effects of chemotherapy.
This changes the nursing frame. Chemotherapy problems follow a predictable nadir, whereas immune-related effects can start weeks or months into treatment, or after it has stopped, and can involve several organs. Management also differs: the drug may be withheld or stopped and systemic corticosteroids or hormone replacement given, decisions that depend on early recognition.
Colitis, hepatitis and pneumonitis
Immune-mediated colitis presents with diarrhoea, increased stool frequency, abdominal pain, or blood or mucus in stools. Patients may assume it is a minor stomach upset and treat it with over-the-counter antidiarrhoeals, so teaching should say clearly that new diarrhoea needs a call to the oncology team. Untreated, frequent stools can quickly lead to dehydration and electrolyte loss.
Pneumonitis presents with new or worsening cough, breathlessness, chest pain or reduced oxygen saturation, and may be mistaken for infection or disease progression. Hepatitis may show as rising liver enzymes, jaundice, dark urine or right upper abdominal pain. The label advises baseline and periodic liver enzymes and creatinine. Kidney inflammation, or nephritis, can also occur.
Endocrine effects that can be permanent
The thyroid, adrenal glands, pituitary and pancreas can all be affected. Hypothyroidism is the commonest endocrine effect in the pembrolizumab label, and hyperthyroidism also occurs. Fatigue, weight change, cold or heat intolerance and palpitations are reported, and thyroid function is monitored. Unlike colitis, endocrine damage often requires lifelong hormone replacement.
Adrenal insufficiency and hypophysitis, inflammation of the pituitary, may present with profound fatigue, headache, nausea, low blood pressure or visual changes and can progress to adrenal crisis. Type 1 diabetes can develop suddenly, sometimes as diabetic ketoacidosis, so excessive thirst, frequent urination, vomiting or confusion require urgent assessment and a blood glucose check.
Skin reactions, infusion care and teaching
Rash and itching are common, but the label also describes severe reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis. Blistering, peeling, mouth sores or skin pain with fever need urgent review. Infusion reactions can occur during administration, so the nurse monitors vital signs and symptoms as for any monoclonal antibody infusion. The label also warns that patients who receive an allogeneic stem cell transplant before or after a PD-1 blocker can develop more severe graft-versus-host disease, so transplant history belongs in the assessment.
Teaching is the main safety tool because many toxicities start at home. Give the patient a written list of symptoms to report and an after-hours number, and ask them to tell any emergency or primary care clinician they have received immunotherapy, so new symptoms are not treated in isolation. Contraception is advised because the drug can harm a fetus.
A hypothetical clinic call scenario
Picture a patient who finished a course of pembrolizumab two months ago and phones the clinic with five or six loose stools a day for three days and cramping. The options are to recommend an over-the-counter antidiarrhoeal and fluids, reassure them that immunotherapy effects stop when treatment ends, arrange same-day assessment through the oncology team, or advise a bland diet for a week.
Arranging same-day assessment is the best response because this pattern suggests immune-mediated colitis, which can occur after treatment stops and may need corticosteroids. An antidiarrhoeal can mask worsening inflammation, the reassurance is false, and diet changes delay care. This is a study scenario, not a real exam question.
Sources and further reading
DailyMed: Keytruda (pembrolizumab) prescribing information. PD-1 blockade, immune-mediated pneumonitis, colitis, hepatitis, endocrinopathies, nephritis and severe skin reactions, timing after discontinuation, corticosteroids, hormone replacement, monitoring and contraception.
National Cancer Institute: Immunotherapy side effects. Side effects occurring during and after treatment, organ inflammation and the importance of reporting symptoms promptly.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our med-surg practice questions are the closest set to what this page covers.
One question from the med-surg set
A client with chronic obstructive pulmonary disease has an oxygen saturation of 88% on 2 L/min via nasal cannula and is alert with no distress. What should the nurse do first?
Rationale
In COPD a saturation of 88–92% is the therapeutic target, not an emergency, and this client is alert with no distress. The first action is the independent nursing intervention that is least invasive and most likely to help: sit them up and reassess. Turning the oxygen up to 6 L/min risks blunting the hypoxic drive, and calling rapid response or drawing an ABG escalates ahead of an assessment you have not finished.
Answer: B
Common questions
Can immunotherapy side effects start after treatment has finished?
Yes. Immune-mediated reactions can begin during treatment or after it ends, so patients should keep reporting new symptoms and tell other clinicians they received immunotherapy.
How is checkpoint inhibitor colitis usually managed?
Depending on severity, the drug may be withheld or stopped and systemic corticosteroids started. Early reporting of diarrhoea allows treatment before dehydration and serious complications develop.
Which endocrine effect often needs lifelong treatment?
Hypothyroidism, adrenal insufficiency, hypophysitis and type 1 diabetes may be permanent and need ongoing hormone replacement or insulin.
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