The short answer
Immunotherapy works by loosening the brakes on the immune system, and sometimes the immune system turns on healthy glands. NCI says adrenal gland inflammation may cause fatigue, muscle weakness, loss of appetite, weight loss, and abdominal pain. These symptoms are vague and easy to blame on treatment, which is why they need reporting.
NCI says adrenal gland inflammation from immunotherapy may cause fatigue, muscle weakness, loss of appetite, weight loss, and abdominal pain.
The endocrine system is one of the organ systems NCI lists as able to be inflamed by immunotherapy.
Pituitary gland inflammation is the most common endocrine problem NCI describes, and may cause headaches and fatigue.
MedlinePlus describes adrenal insufficiency as the adrenal glands not producing enough hormones.
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When to get help sooner
Call 911 if someone on immunotherapy has difficulty breathing, becomes dizzy or lightheaded and cannot stay upright, or has a reduced level of consciousness. MedlinePlus lists these among the signs of adrenal crisis and says that if adrenal crisis symptoms are present and prescribed emergency medicine is not available, go to the nearest emergency room or call 911.
Call your care team the same day about new or worsening fatigue, muscle weakness, loss of appetite, unexplained weight loss, or abdominal pain while you are receiving immunotherapy. NCI lists exactly these as possible signs of adrenal gland inflammation. Tell whoever answers that you are on immunotherapy — it changes how they think about your symptoms.
Why immunotherapy can hit a gland
Immunotherapy does not attack cancer directly. It takes the brakes off your immune system so it can do that job. The trade-off: a less restrained immune system sometimes attacks healthy tissue too.
NCI calls this inflammation. It lists where it can happen: the digestive system, the endocrine system, joints and muscles, the respiratory system, skin, blood, eyes, heart, kidneys, liver, and nervous system. The endocrine system means the hormone glands. That includes the adrenals, which sit on top of the kidneys. It also includes the pituitary, which sits under the brain.
The symptoms are frustratingly ordinary
Here is what NCI says adrenal gland inflammation may cause: "fatigue, muscle weakness, loss of appetite, weight loss, and abdominal pain."
Read that list again. See the problem. Every single item is something a person having cancer treatment might expect to feel anyway. Nobody in treatment is surprised by tiredness or a poor appetite.
That is exactly why this side effect gets missed. It does not announce itself. It hides inside complaints everyone has already decided are normal.
Do not filter your symptoms before you report them. Let the team decide what is ordinary.
The pituitary connection
NCI notes that pituitary inflammation is the most common endocrine problem tied to this treatment. It may cause headaches and fatigue.
The pituitary matters because it works as a control switch for other glands, including the adrenals. So a hormone problem after immunotherapy can start in either place. From where you sit, the response is the same either way: report the symptoms. Let blood tests find the cause.
What low adrenal hormones do
MedlinePlus explains that in adrenal insufficiency, the adrenal glands do not make enough hormones. The resulting picture includes abdominal pain, ongoing diarrhea, nausea and vomiting, darkening of the skin, extreme weakness and fatigue with slow, sluggish movement, low blood pressure, and salt craving.
The dangerous end of this is adrenal crisis. MedlinePlus describes it as abdominal pain, difficulty breathing, dizziness or lightheadedness, low blood pressure, and reduced level of consciousness. That is an emergency. Do not wait to see if it passes.
What to do with this
You are not being asked to diagnose yourself. You are being asked to notice a change and say so.
A useful habit is to describe things as differences, not labels. Try: "I am more tired than I was three weeks ago and I have stopped wanting food." That tells a nurse more than "I think I might have an endocrine problem."
Ask your team in advance which symptoms call for a phone call and which call for urgent care. NCI suggests asking this directly. Knowing the answer before you feel unwell is much easier than working it out at ten at night.
Words to know
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Common questions
How would I tell this apart from ordinary treatment tiredness?
Often you cannot, and that is the honest answer. NCI's list for adrenal inflammation — fatigue, muscle weakness, loss of appetite, weight loss, abdominal pain — overlaps heavily with how cancer treatment makes people feel anyway. That overlap is the reason to report the symptoms rather than to try to sort them out yourself. Blood tests can distinguish what you cannot.
What are the adrenal glands actually for?
MedlinePlus describes adrenal insufficiency as a disorder in which the adrenal glands do not produce enough hormones. Those hormones affect blood pressure, salt balance, and how the body handles stress, which is why low levels show up as weakness, low blood pressure, and feeling faint.
Does this mean immunotherapy has to stop?
That is a decision for your oncology team based on how you are and what the tests show, and it is not something an article can answer. NCI's advice is to ask your care team ahead of time what side effects to call about and which ones need urgent care.
Can this happen after treatment has finished?
NCI does not give a fixed window on this page, and instead lists it as something to ask about — specifically when side effects might start and how long they might last. Bring that question to your team rather than assuming the risk ends on your last infusion day.
Questions to ask your doctor
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Sources last checked: 2026-08-11 what this meansLast updated: 2026-08-11Next planned review: 2027-08-11
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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