Symptoms and Emergency Warning Signs

When you are undergoing immunotherapy, your body is in a state of high activity. While this helps fight cancer, it can also lead to immunotherapy-induced hypophysitis (IIH), where the immune system attacks the pituitary gland. The most dangerous consequence of this attack is the loss of cortisol, a vital hormone that helps your body manage stress, maintain blood pressure, and regulate blood sugar ^[1][2].

Without enough cortisol, you can slide from “feeling unwell” into a life-threatening medical emergency called an adrenal crisis ^[3][4].

The Challenge: Symptoms That “Hide”

One of the most difficult parts of IIH is that its early symptoms often look exactly like the side effects of cancer or chemotherapy. Many patients and even some doctors may mistake these warning signs for general “cancer fatigue” ^[5][6].

You should be highly suspicious of IIH and contact your oncology team immediately for blood tests if you notice a cluster of these symptoms appearing or worsening together ^[7]:

• Profound Weakness: A feeling of being “drained” that does not improve with rest ^[7].
• Persistent Nausea or Loss of Appetite: A new or worsening “queasiness” or simply having no desire to eat ^[5][6].
• Headaches: New or unusual headaches, which may be caused by inflammation in the pituitary gland ^[8].
• Dizziness: Feeling lightheaded, especially when you stand up quickly ^[8][9].

While a mild, stable skin rash from immunotherapy is generally not an emergency, immune-related skin reactions can become urgent. If a rash includes blistering, peeling, severe pain, mouth or eye involvement, or facial swelling, you must seek urgent medical care.

Emergency Red Flags: The Adrenal Crisis

An adrenal crisis occurs when your body’s cortisol levels drop so low that your vital systems begin to fail. This is a life-threatening emergency that requires immediate medical intervention, usually in the form of intravenous (IV) fluids and steroids ^[3][10].

Seek emergency care immediately (call an ambulance, do not drive yourself) if you experience any of the following “Red Flag” symptoms:

• Persistent Vomiting or Diarrhea: If you cannot keep your oral medications or fluids down, an adrenal crisis is imminent ^[11][12].
• Confusion or Altered Mental State: Feeling unusually drowsy, disoriented, or “foggy” ^[13].
• Extreme Low Blood Pressure (Hypotension): You may feel severely faint or actually collapse. This often does not improve even if you drink plenty of water ^[2][13].
• Fainting or Syncope: Any loss of consciousness, even brief, is a major red flag ^[14].
• High Fever: A high fever acts as a severe physical stressor that rapidly depletes your body’s cortisol, often precipitating an adrenal crisis. Any fever requires prompt clinical evaluation ^[15][14].
• Vision Changes: Sudden visual loss, double vision, or rapidly worsening headaches require urgent assessment, as they can indicate the pituitary gland is swelling and pressing on the optic nerves ^[16].

What Happens in the Body During a Crisis?

During an adrenal crisis, your body loses its ability to maintain balance. Doctors will look for specific signals in your bloodwork:

• Hyponatremia: Dangerously low levels of sodium in your blood ^[1][7].
• Hypoglycemia: Dangerously low blood sugar levels ^[17].
• Potassium Differences: Unlike primary adrenal insufficiency where the adrenal glands themselves are damaged and potassium levels spike, IIH involves the pituitary gland. Because the pituitary doesn’t strongly control the hormone that regulates potassium, your potassium levels will often be normal. A normal electrolyte panel does not mean you are safe ^[7].

Don’t Wait for “Proof”

If you are in an emergency room and suspect an adrenal crisis, it is vital to tell the staff: “I am on immunotherapy, I have adrenal insufficiency, and I may be having an adrenal crisis.”

Guidelines state that if a crisis is suspected, doctors should start treatment with life-saving steroids immediately—they should not wait for blood test results to confirm the diagnosis before giving you the medication you need ^[3][18]. Delaying treatment to wait for a “perfect” lab result can be fatal ^[2].

If you have an emergency injectable kit at home and are experiencing the “Red Flags” listed above, use it as instructed by your doctor while someone else calls for an ambulance ^[11].