Managing Diarrhea During Cancer Treatment

For people whose treatment is causing loose stools, here is what drives it, how to replace lost fluid, what to eat for now, and which signs are urgent.

Diarrhea means loose or watery stools that come more often than usual. Some chemotherapy drugs cause it. So can radiation to the abdomen or pelvis, some targeted therapies, and immunotherapy. Infections and certain medicines can cause it too. Diarrhea makes the body lose fluid and salts fast, which can lead to dehydration and weakness. So it is worth acting on and reporting early, rather than waiting to see if it settles.

The first priority is replacing what you are losing. Sip fluids steadily through the day. Include some that provide salts and a little sugar. Clear liquids such as water or broth, at room temperature, can help. NCI says to avoid fruit juices, alcohol, and caffeinated drinks while you have diarrhea. Call your team if you cannot keep fluids down, or if you feel dizzy and are passing little urine.

Many people do better for a while with bland, easy-to-digest, lower-fiber foods. Bananas, white rice, applesauce, toast, plain crackers, eggs, and skinless chicken are common choices. Eating smaller amounts more often is usually gentler than large meals. NCI suggests limiting high-fat foods, spicy foods, dried beans, fruit juices, sugar-free gum and candy, caffeine, and alcohol until things settle. NCI also lists milk and dairy products among foods to avoid.

It is safest not to start anti-diarrhea medicine on your own during treatment without checking first. The right approach depends on the cause. If an infection is behind it, slowing the bowel can make things worse. Your team may give you a medicine and clear instructions for when to use it. Everyone's situation is different. This is general information, not advice for you personally. Your care team can tailor it to your treatment, and so can an oncology dietitian if one is available.

Diarrhea can lead to dehydration. Report it early, even if it feels mild.

• Call 911 or go to an emergency department if you feel faint or confused, your heart is racing, or you cannot stand up without nearly passing out. Do not drive yourself.
• Ring your cancer team immediately, at any hour, if your temperature reaches 100.4°F (38°C) or higher during chemotherapy, with or without diarrhea. CDC says a fever during chemotherapy is a medical emergency, and an infection during chemotherapy can be life-threatening. If you cannot reach them, go to the emergency room and tell the staff you are on chemotherapy.
• Call 911 or go to an emergency department if severe belly pain comes with fever and diarrhea, or your belly becomes swollen and tender to touch. That combination can mean a serious bowel infection. Do not drive yourself.
• Call 911 or go to an emergency department if you see black, tarry stool or red blood in your stool, or you vomit blood or material that looks like coffee grounds. That can mean bleeding in the gut (MedlinePlus). Do not drive yourself.
• Call your care team right away, at any hour, if you cannot keep fluids down, or you have passed little or no urine for eight hours or more. If you are on chemotherapy, CDC lists diarrhea and vomiting among the signs of infection to call about right away (CDC).
• Call your care team the same day if you are on immunotherapy and have any new diarrhea. It can be a sign of bowel inflammation that needs treatment quickly.
• Call your care team within a day or two if you have more loose stools a day than usual and it is not settling, or your bottom is becoming raw and sore.

Ask your team in advance how many loose stools in a day should make you call.

• National Cancer Institute — Diarrhea and Cancer Treatment
• CDC — Fever and Cancer Treatment
• National Cancer Institute — Eating Hints: Before, During, and After Cancer Treatment
• National Cancer Institute — Nutrition During Cancer Treatment