Diarrhea and Cancer Treatment

What diarrhea isExplain▾

Diarrhea means having bowel movements (stools) more often than normal. The stool may also be soft, loose, or watery. It is a common side effect of many cancer treatments, such as chemotherapy, immunotherapy, and radiation therapy.

When you have severe diarrhea, your body does not absorb enough water and nutrients. This can lead to serious problems such as dehydration—not having enough water in the body. Dehydration can be life-threatening, so tell your doctor or nurse if you have diarrhea.

Your doctor will find the cause and recommend ways to feel better, which may include medicines and foods that help decrease or stop diarrhea.

What causes itExplain▾

Frequent diarrhea can be a sign of some cancers or a side effect of treatment. Causes in people with cancer include:

• Certain types of cancer, especially cancers that form in the abdomen or digestive tract.
• Chemotherapy, which can destroy healthy cells that line the digestive tract along with cancer cells.
• Immunotherapy, especially immune checkpoint inhibitors, which can inflame the colon (colitis) and lead to diarrhea.
• Radiation therapy aimed at the abdomen, pelvis, or rectum, which can damage healthy digestive tissue.
• Surgery to the esophagus, stomach, gallbladder, or bowel.
• Targeted therapy, a common cause of diarrhea for many of these drugs.
• Bone marrow or stem cell transplant, from the medicines and radiation used, or from graft-versus-host disease.

Other causes include stress and anxiety, some medicines (such as antibiotics), certain supplements and herbal products, infections, and conditions like irritable bowel syndrome.

Symptoms and gradesExplain▾

Signs and symptoms of diarrhea include soft, loose, or watery stools, going more often than normal, an urgent hard-to-control need to go, belly pain or cramps, and excess gas. Some people also have blood or mucus in the stool, feel dizzy, have a fever, or lose weight.

Your doctor will talk with you to figure out the severity, or grade, of your diarrhea. Grade is based on how many bowel movements you have compared with your normal number.

• Grades 1 and 2 (up to six extra bowel movements a day) can usually be managed at home.
• Grades 3 and 4 (seven or more extra bowel movements a day) can be life-threatening and may need treatment in a hospital.

How it is diagnosedExplain▾

Finding the cause is important so you can get relief before it interferes with treatment or causes dehydration. Your doctor may ask how many bowel movements you've had, what they were like, and what you've been eating and drinking. They will do a physical exam and may use stool tests, blood tests, a urine test, or a digital rectal exam.

Ways to treat and control itExplain▾

Treatment depends on the cause and grade. Your doctor may suggest diet changes and prescribe medicines. You may receive fluids through a vein (IV) to replace what you lost. If chemotherapy is causing severe diarrhea, your doctor may lower your dose or pause it until you feel better.

Everyday tips:

• Drink lots of fluids. Clear liquids such as water or broth replace fluids and minerals. Room-temperature liquids are easiest on the stomach. Ask your team how much to drink.
• Eat small meals. Frequent small meals or snacks may be easier than three large ones.
• Choose low-fiber foods such as white bread, pasta, and canned fruit.
• Eat foods high in sodium and potassium such as boiled potatoes, soup, bananas, applesauce, and crackers.
• Avoid foods that can make it worse, including alcohol, dairy, spicy foods, caffeine, dried beans, fatty foods, fruit juices, and sugar-free gum or candy.
• Keep your bottom clean and dry. Warm water and baby wipes help, and a warm, shallow sitz bath can soothe irritation.
• Keep a record of your bowel movements to share with your team.

MedicinesExplain▾

For severe diarrhea during treatment, your doctor may prescribe loperamide (Imodium) or a combination of diphenoxylate and atropine (Lomotil). They may also suggest probiotics or fiber supplements. Check with your doctor before taking these or any other medicines and supplements.

Getting supportExplain▾

Diarrhea can be hard to deal with, both physically and emotionally. Ask your health care team for support. If you are caring for someone with diarrhea, you can help by encouraging fluids, keeping helpful foods on hand, tracking bowel movements, and asking the team when to call.