Immunotherapy Colitis: What to Ask

This page is for people getting immunotherapy who have diarrhea or other bowel changes. Immunotherapy colitis is inflammation (swelling and irritation) of the colon. It can happen with immune checkpoint inhibitors, a type of immunotherapy. Diarrhea during immunotherapy may have more than one cause. The team may need to check for infection, for medicines, for diet changes, or for cancer-related issues too.

This page is a planning aid. It cannot diagnose the cause of a symptom, and it does not replace the instructions from your oncology team.

Diarrhea on immunotherapy is not the same as a stomach bug. The first thing your team will ask is how many loose stools you are having a day. Count them against your normal, not against zero. NCI says the grade of diarrhea is based on how many bowel movements you have per day compared with your normal number.

• Call 911 or go to the nearest emergency department if… you pass black or tarry stools, you vomit blood or coffee-ground material, you have heavy bleeding, or you are confused or hard to wake. NCI lists black or bloody stools as a sign of colitis from immunotherapy.
• Call 911 or go to the nearest emergency department if… you have severe abdominal pain, a rigid or very tender abdomen, you are vomiting and cannot keep fluids down, or you are light-headed and passing little urine or cannot urinate at all.
• Call your care team right away, day or night, if… you have more loose stools than your usual, diarrhea that wakes you at night, or blood or mucus in your stool. Ask your team ahead of time what number of extra stools they want a call about.
• Call your care team right away, day or night, if… you have a fever of 100.4°F (38°C) or higher, chills, a sore throat, mouth sores, or burning when you urinate. This applies most if you are also on chemotherapy or your white blood cell count is low. A normal temperature is not a reason to wait. Also call right away for abdominal pain or cramping that keeps building, or for dizziness or light-headedness.

NCI says your oncologist may advise you to call first about these symptoms, or to seek emergency care. Ask ahead which applies to you. Side effects can start at different times. Ask how long after treatment they can occur. Tell any clinician you see that you have had immunotherapy, even if it was a while ago. Check with your team before you take any medicine for diarrhea.

Bowel inflammation can lead to dehydration, bleeding, pain, or treatment interruptions. It may also mean you need medicines that calm immune inflammation. The care team needs timing, stool pattern, related symptoms, and treatment history.

Many treatment side effects are easier to handle when the team hears about them early. If your team already gave you an urgent call plan, use that plan first.

• Stool frequency compared with your usual baseline.
• Blood, mucus, severe cramping, fever, dizziness, or signs of dehydration.
• The immunotherapy drug name and your most recent infusion date.
• Recent antibiotics, laxatives, stool softeners, supplements, or diet changes.
• Fluid intake, weight change, and whether symptoms are improving or worsening.

• What is the most likely cause in my situation, and what else needs to be ruled out?
• Which symptoms or changes mean I should call right away for my exact treatment?
• What information should I track before I call or come in?
• Could this affect treatment timing, dose, or supportive medicines?
• Who should I contact after hours, and what should I say first?

The plan may include stool testing, blood work, or hydration. It may include medicines, holding immunotherapy, steroid treatment for selected cases, or gastroenterology input.

Ask what result or symptom pattern would change the plan. Ask what can be watched, and what should not wait until the next routine visit.

• Do not assume a symptom is "just treatment" without checking the plan your team gave you.
• Do not assume the same symptom means the same thing for every cancer treatment.
• Do not start a new over-the-counter medicine, supplement, or major diet change without asking the care team while symptoms are active.

Helpful next pages include Diarrhea During Cancer Treatment and Immune-Related Side Effects. Also see Immunotherapy Pneumonitis: What to Ask, Immunotherapy Hepatitis: What to Ask, and What Is Immunotherapy? Cancer and the Immune System.