Skip to Main Content

Welcome to

Together is a new resource for anyone affected by pediatric cancer - patients and their parents, family members, and friends.

Learn More


What is diarrhea?

Diarrhea is a condition where stools become loose or watery and occur more often. A person may have cramping or lose control of bowel movements.

In general, diarrhea may be defined as passing more than 3 loose stools in 24 hours.

Diarrhea is a common side effect in children who are living with serious illnesses. It can have different causes including chemotherapy, antibiotics, and infection. In some cases, diarrhea can lead to serious health problems such as dehydration, malnutrition, and metabolic imbalances.

Ways to manage diarrhea include anti-diarrhea medicines and changes to diet. It is also important to make sure your child stays hydrated by drinking liquids or receiving IV fluids.

If diarrhea is caused by a virus or bacteria, treatment of the infection may be needed. If diarrhea is caused by treatment such as chemotherapy, your child’s care team may modify the treatment schedule until symptoms improve.

Causes of diarrhea in children with serious illnesses

  • Antibiotics and other medicines
  • Bone marrow transplant
  • Chemotherapy
  • Effects of their medical conditions
  • Infection
  • Radiation therapy
  • Stress and anxiety
  • Surgery

Assessment of diarrhea

Assessment of diarrhea considers:

  • Number of episodes per day
  • Appearance of stool
  • Loose
  • Liquid
  • Watery
  • Incontinence
  • Waking during the night
  • Getting in the way of daily activities

The care team might you to describe what your child’s stools look like using a chart. They will also evaluate other signs and symptoms such as:

  • Fever
  • Pain and cramping
  • Weakness or dizziness
  • Rectal bleeding or blood in stools
  • Nausea and vomiting
  • Weight and hydration

Lab tests may check blood counts, electrolyte levels, and kidney function.

Stool may be tested to look for viruses or bacteria. Common sources of infection with diarrhea are:

  • Rotavirus
  • Adenovirus norovirus
  • Salmonella
  • Campylobacter
  • Shigella
  • Clostridioides difficile

Diarrhea due to infection may need different treatment.

The care team will also evaluate other possible reasons for diarrhea such as medicines, diet, and situational factors.

Less often, assessment of diarrhea may include imaging tests to view the gastrointestinal tract.

Diarrhea and constipation are common problems in children with serious illnesses such as cancer.

Health problems from diarrhea

Diarrhea can be life-threatening. Possible health problems due to diarrhea include:

  • Dehydration
  • Malnutrition
  • Electrolyte imbalances
  • Kidney failure

In some cases, chemotherapy and other treatments may be delayed until symptoms improve.

Causes of diarrhea

Nutrients and water are absorbed as food moves through the digestive tract. Waste is passed out of the body as stool. The intestines secrete digestive fluids and mucous to help break down and move contents.

Bacteria are also found in the digestive tract and help break down food.

Sometimes, stools become too watery if fluids are not absorbed or if secretions increase. Medicines can also change the balance of bacteria in the intestines. An increase in movement of the intestines can also cause stool to pass through more quickly.

A change or imbalance in one or more of these digestive processes can trigger diarrhea.

Factors that may lead to diarrhea in children with serious illnesses may include:

Chemotherapy-induced diarrhea

Diarrhea is a common side effect of chemotherapy. This is sometimes called chemotherapy-induced diarrhea or CID. Chemotherapy may cause diarrhea in different ways.

Chemotherapy can damage the mucous membrane lining the intestines. Certain drugs can also change the fluid balance in the intestines. Fluid may not be absorbed properly, or extra fluid or mucous may be secreted.

Chemotherapy can also interfere with absorption of nutrients or change the way digestive enzymes work in the intestines.

Medicines that can cause diarrhea

Medicines with High Risk of Diarrhea Medicines with Moderate Risk of Diarrhea
Busulfan Cyclophosphamide
Capecitabine Daunorubicin
Dasatinib Etoposide
Docetaxel Interferon
Fluorouracil (5-FU) Melphalan
Idarubicin Methotrexate
Imatinib Nivolumab
Irinotecan Paclitaxel
Mycophenolate Topotecan
Pazopanib Vincristine

Diarrhea can be a side effect of other common medicines used in pediatric cancer patients. This may occur for different reasons. Some medicines cause an imbalance of “good” and “bad” bacteria in the stomach and intestines. Other medicines can affect the breakdown of food or how much fluid is absorbed or produced.

Medicines that may cause diarrhea include antibiotics such as:

  • Ampicillin
  • Amoxicillin,
  • Amoxicillin-clavulanate
  • Cefixime
  • Clindamycin
  • Erythromycin

Stool softeners, laxatives, antacids with magnesium, potassium chloride, and proton pump inhibitors may also cause diarrhea.

Radiation therapy and diarrhea

Radiation to the abdomen, back, or pelvis can cause diarrhea. Radiation triggers cell death in fast-growing cells, like the cells that line the intestines. This is known as radiation enteritis.

Symptoms include nausea, vomiting, cramping, fatigue, and diarrhea. Stools may be watery or contain blood or mucous.

Radiation enteritis usually improves 2-3 weeks after treatment ends, but symptoms can last 12 weeks or longer. If your child develops radiation enteritis, they may have longer lasting diarrhea or have problems with diarrhea later in life.

Factors that increase risk for diarrhea with radiation therapy include:

  • Higher dose and frequency of radiation treatments
  • Greater treatment area involving the intestines
  • Radiation given along with chemotherapy

Treatment of radiation-induced diarrhea includes using medications such as loperamide and octreotide.

Other causes of diarrhea

Managing diarrhea

Diarrhea can cause serious health problems. It is to work closely with your child’s care team to manage symptoms. Strategies to help treat diarrhea include anti-diarrhea medicines and changes in diet.

It is important to stay hydrated when dealing with diarrhea. If diarrhea is severe or your child can’t take enough fluids by mouth, they may need treatment for dehydration.

Anti-diarrhea medicines

Possible medicines for diarrhea include loperamide (Imodium®) and antibiotics.

In special cases, atropine and octreotide can be used to treat certain types of diarrhea.

Probiotics help in some cases. But your child should only use these under a care team’s supervision.

Your child’s care team will help you find the best treatment.

What to eat when you have diarrhea

Your child’s care team may suggest dietary changes including smaller meals, bland foods, and caffeine-free liquids.

Your child’s care team might also recommend the BRAT (Bananas, Rice, Applesauce, and Toast). This diet is low in important nutrients, so only follow it for a few days or as recommended by the care team.

Other foods may include oats, low-sugar cereals, crackers, pasta without sauce, and soft, peeled fruits like peaches or pears. Broth-based soups with cooked vegetables and lean meats can be a good way to restart solid foods and increase fluid intake.

Some foods can make diarrhea worse. These include spicy or greasy foods, milk and dairy products, raw fruits and vegetables, dried fruits, some fruit juices, foods high in fat or sugar, and caffeine.
If diarrhea is caused by GVHD, your child may need a special diet. Talk with your child’s care team about it.

Nutrition tips to help with diarrhea include:

  • Drink plenty of fluids. Choose water or caffeine-free and low-sugar drinks such as Pedialyte® and lower sugar sports drinks.
  • Eat smaller meals, eat slowly, and chew food well.
  • Choose mild foods that don’t upset the stomach.
  • Avoid alcohol and caffeine.
  • Limit foods high in insoluble fiber such as whole fruits and vegetables with skins or seeds.
  • Soluble fiber found in oatmeal, applesauce, bananas and some fiber supplements may help firm loose stool.
  • Avoid foods that could make gas and cramping worse. These include beans, broccoli, cauliflower, cabbage, and carbonated beverages.
  • Offer foods high in potassium like bananas, potatoes, apricots, and peaches.


  • Bananas
  • Rice
  • Applesauce
  • Toast, white bread
  • Oatmeal
  • Cream of rice or wheat
  • Noodles
  • Mashed potatoes
  • Crackers
  • Pretzels
  • Fruit without skin
  • Cooked vegetables without skin
  • Cooked eggs
  • Low-sugar yogurt
  • Ice pops or sherbet
  • Fruit-flavored gelatin


  • Greasy or fried foods
  • Spicy foods
  • Caffeine
  • Milk products (especially if lactose intolerant)
  • Raw fruits and vegetables with skin
  • Popcorn
  • Nuts and seeds
  • Bran
  • Whole grains
  • Alcohol

Find more nutrition tips to help with side effects

Tips for families

  • Diarrhea can be serious. Monitor and discuss symptoms with your care team. Watch for signs of dehydration such as thirst, dry mouth, headache, feeling dizzy, muscle cramps, not peeing enough, irritability, and lack of energy.
  • Prepare your child for the possibility of diarrhea and other side effects. Keep communication honest and open. 
  • Encourage rest to help slow bowel action. If your child is anxious or afraid, try ways to manage anxiety. Physical activity and stress can stimulate movement of the intestines.
  • Frequent stools can irritate the skin. Be sure to clean gently but thoroughly, and keep the area dry. Use a barrier cream or ointment as recommended by the care team. Diaper dermatitis can occur at any age, causing discomfort and increasing risk for infection. 
  • Older children and teens who have pain may not clean as well after going to the bathroom, which will make skin problems worse. 
  • For children with weak immune systems, any breakdown of the skin can lead to serious infection. Watch for skin changes, and discuss skin care with your doctor.
  • Carry an extra change of clothes and plastic bags for dirty items. Keep disposable gloves, cleansing wipes, and hand sanitizer on hand for cleanup. A travel-sized air freshener or deodorizer can help lessen odors.
  • Pads and underwear may be needed for accidents or incontinence. Youth and adult size products are available including liners, pull-on briefs, and diaper covers. Talk to your care team about items available from your hospital or home health company.
  • Help your child make a plan for using the bathroom at school or public places. Make sure teachers allow bathroom use at any time. Have a code word or signal to use when your child needs a bathroom immediately but might be too embarrassed to say.

does not endorse any branded product mentioned in this article.

Reviewed: September 2022