Discussion – 


Diarrhea and Cancer: How and What to Eat

Many people living with cancer experience diarrhea — either as a side effect of treatment or a symptom of their cancer. Diarrhea can cause daily disruptions and lifestyle changes, but with preventative and nutrition-based management strategies, it can often be improved.

What is diarrhea?

Diarrhea is defined, in relation to your normal bowel habits, as having more frequent, loose, or watery bowel movements (or “stools”). Diarrhea can range from mild to severe — meaning you might experience anywhere from 1-7 or more extra trips to the bathroom compared to your “norm.”

What causes diarrhea?

Diarrhea during cancer is usually caused by one or a combination of the following:

  • Treatments, including chemotherapy, immunotherapy, and or radiation therapy
  • A specific type of cancer — pancreatic cancer, colon cancer, and ovarian cancer are particularly likely to cause diarrhea
  • Changes in diet due to cancer symptoms or treatment side effects, like eating more/less or eating different foods
  • Antibiotics or medications you are taking
  • Anxiety or stress
  • Other medical conditions that may be pre-existing or that arise alongside cancer or cancer treatment

Managing diarrhea with nutrition-based strategies

For many people living with cancer, paying close attention to what, when, and how you eat can decrease the frequency and severity of cancer-related diarrhea.

  1. Eat a diet that’s low in fiber (less than 10 grams per day). High-fiber diets (one rich in fruits, veggies, whole grains, nuts, seeds, and legumes) are often thought of as “healthy,” though may not be the best choice if you’re dealing with diarrhea. Fiber (in large or small amounts) can irritate the intestines, so try to limit your intake to 10 grams of fiber or less per day if you’re experiencing moderate to severe diarrhea. Once diarrhea subsides, you can gradually increase your fiber again. (For examples of low-fiber foods, see the chart below.)
  2. Choose bland, easy-to-digest foods. If you’re experiencing diarrhea, shift your diet to include mainly foods that are blander and easy to digest. Choosing all-natural, minimal-ingredient foods like what you might eat when you have the stomach flu can help ensure you’re not irritating your digestive system with high-fat, greasy, harsh, spicy, or complex foods that can worsen diarrhea. Make sure the foods you choose represent a wide variety of food groups so that you’re getting well-balanced nutrition. (For examples of bland, easy-to-digest foods, see the chart below.)
  3. Eat small, frequent, slow, and strategically timed meals. Rather than eating three large meals, try eating 5-6 smaller meals and/or snacks throughout the day. Smaller amounts of food are sometimes easier for your body to digest and can help avoid overwhelming your digestive system (which in turn triggers diarrhea). Change up your behaviors around meals and snacks to further aid digestion: adjust the timing of your meals and snacks to figure out what works for you and avoid eating too close to bedtime. Also, avoid eating quickly and make sure that you are thoroughly chewing your food before you swallow it.
  4. Avoid extreme temperatures. Eating foods that are extremely hot or extremely cold can irritate your digestive system and leave you at risk of having diarrhea. Stick to a small, happy medium range of temperatures instead.
  5. Avoid non-food irritants. Certain substances are more likely to cause digestive irritation and diarrhea. Avoid tobacco, alcohol, and sugar-free products that contain sorbitol, mannitol, or xylitol.
  6. Stay hydrated. Diarrhea can cause dehydration. Avoid this dangerous side effect by drinking at least 8 cups of fluid each day — sipping them slowly to avoid overwhelming your digestive system. Except for alcohol, all fluids count towards your daily goal including water, juice, electrolyte beverages (like Pedialyte or Gatorade), broth, carbonated beverages, herbal teas, and anything that melts (like juice bars, popsicles, or crushed ice).
    Good to know: to prevent dehydration after an episode of diarrhea, aim to drink at least 8 ounces of fluid in the 1-2 hours after to replenish the liquid your body lost. Avoid caffeinated beverages whenever possible, as these can also lead to dehydration.

What to eat

Below is a list of foods we recommend in the various food groups for patients experiencing diarrhea. Eliminating “avoid” foods may help in relieving or preventing diarrhea.

FOOD GROUPWe recommend eating…Foods that are typically easy to digestWe recommend avoiding…
Foods that are more likely to irritate your stomach
FruitsThe following fruits are allowed if they are cooked, peeled, or canned:

  • Apples
  • Cherries
  • Blueberries
  • Peaches
  • Nectarines
  • Pears
  • Plums
  • Pineapple
  • Apricots
  • Fruit Cocktail

The following fruits can be eaten raw:

  • Applesauce
  • Avocado
  • Bananas
  • Melons – cantaloupe, honeydew, watermelon (without the seeds)
All raw fruits except those listed as recommended:

  • Dried fruits
  • Fruits with skins
  • Fruits with seeds that can’t be removed – strawberries, raspberries, blackberries, kiwi
  • Prune juice


VegetablesThe following vegetables are allowed if they are cooked, peeled and seeds are removed:

  • Asparagus tips
  • Beets
  • Butternut squash
  • Carrots
  • Cucumbers
  • Eggplant
  • Green beans
  • Mushrooms
  • Potatoes
  • Sweet potatoes
  • Spaghetti squash
  • Summer squash
  • Zucchini
  • Wax beans
  • Tomatoes
  • Artichokes
  • Legumes (kidney, black, pinto, chickpeas, lentils)
  • Broccoli
  • Brussels sprouts
  • Cauliflower
  • Cabbage
  • Green leafy vegetables (greens, spinach, etc)
  • Peas
  • Corn
  • Peppers
  • Onions
  • Salads
Bread and CrackersRefined flour breads, including the following:

  • White bread
  • Sour dough
  • Light rye without seeds
  • French bread without seeds on the crust
  • Potato bread
  • Oatmeal bread
  • White flour bagels, English muffins pita bread and tortillas
  • Crackers made with white flour, like saltines, Ritz, oyster crackers, soda crackers, rice cakes, original (plain) Melba toast
  • Bread products made with bran; whole wheat and other whole grains; cracked or sprouted wheat; and breads made with dried fruit, seeds, or nuts.
  • Doughnuts
  • Croissants
Cereals, Rice and PastaLow fiber cereals, including the following:

  • Rice and Corn Chex
  • Cornflakes
  • Special K without dried fruit
  • Puffed rice
  • Rice Krispies
  • Cheerios
  • Oat Squares
  • Oatmeal
  • Cream of Wheat or Rice
  • Farina
  • Grits
  • White riceRegular pasta, orzo, couscous
  • High fiber cereals made with whole grains, bran, nuts, seeds (including flaxseeds), berries and dried fruits; granola; wheat germ.
  • Brown or wild rice
  • Quinoa, barley, farro, amaranth
  • Whole grain pasta and couscous
  • Lean beef or pork (loin, round, or flank cuts, or 90% lean)
  • Skinless chicken or turkey
  • Fish and shellfish
  • Lamb
  • Veal
  • Liver
  • Eggs
  • Creamy nut butter (peanut, almond, cashew, sunflower)
  • Low fat cheese
  • Tofu
  • Chicken and turkey skin
  • Fatty meats
    Fatty luncheon meats, like bologna, mortadella, salami.
  • Hot dogs
  • Bacon and sausages
  • Whole nuts and seeds
  • Chunky nut butters
Milk and Milk Products
  • 1% low fat or non-fat milk
  • 1% low fat or nonfat regular or Greek yogurt
  • Reduced fat cheese with 6-7 grams of fat per ounce, such as American cheese, light cheddar, feta cheese, goat cheese, Babybel and Laughing Cow
  • Pudding
  • Soy and other plant-based beverages (almond, cashew, rice, coconut, and pea protein milks)
  • Cream
  • Creamed soups
  • Chocolate and other flavored milks
  • Whipped cream

*Some people find that they need to avoid dairy products altogether when they have diarrhea because their body has a hard time tolerating the lactose contained in those products.

FatsSmall amounts of vegetable oil, tub spreads (Smart Balance, Olivio, Earth Balance), butter and mayonnaise (may need to experiment but to assess tolerance so start small).
  • Fried foods
  • Gravy
  • Shortening
  • Large amounts of oil, tub spread, butter or mayonnaise
DessertsLow fat desserts like angel food cake, vanilla wafers, and others with less than 3 grams of fat per serving, gelatin, pudding, sherbet, and sorbet.High fat desserts like frosted cakes, coffee cake, pie, ice cream, higher fat cookies, and desserts made with nuts, seeds, coconut, dried fruit, or fruits with skins
Spices and CondimentsMild spices like salt, ginger, dried thyme, rosemary, or chives.  Black pepper as tolerated.Cayenne pepper, chili powder, chili peppers, garlic, and spicy sauces.

More ways to manage diarrhea

In addition to changing what and how you eat, you might also try one or more of the following to prevent and manage diarrhea during cancer:

  • Medication: Your doctor or the Iris Care Team may be able to prescribe an anti-diarrheal (or help you determine if you should buy one over the counter)
  • Symptom tracking: Tracking your cancer-related symptoms can help you and your doctor better understand the cause of your diarrhea and try new management strategies based on that information.

Communicating with your care team

Even if mild, cancer-related diarrhea can have a major impact on quality of life. In severe cases, diarrhea can be dangerous and can cause dehydration, electrolyte problems, weight loss and infections amongst other potential issues. If you’re having any of the following symptoms, contact your Iris nurse or call your doctor immediately to get help and advice on the next steps:

  • A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher
  • Moderate to severe abdominal cramping, pain, straining or bloating that’s causing discomfort or major life disruptions
  • Dizziness or confusion (this could indicate significant dehydration)
  • Dark urine (this means your urine is concentrated, and could indicate significant dehydration)
  • Black or bloody stools
  • If dietary measures and medications do not improve the diarrhea

Given the potential for life-threatening complications, it’s important to communicate with your care team about any new or worsening diarrhea throughout your cancer — no matter how mild it may seem. Consider tracking your diarrhea along with any other symptoms/side effects so that you have concrete information to share with your doctor about timing and severity. Your medical team will monitor your weight and electrolytes to determine if you’d benefit from any extra supportive care, treatment changes or additional medications.

More resources for managing diarrhea during cancer:


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Reviewed by the Iris Clinical Editorial Board
This article meets Iris standards for medical accuracy. It has been fact-checked by the Iris Clinical Editorial Board, our team of oncology experts who ensure that the content is evidence based and up to date. The Iris Clinical Editorial Board includes board-certified oncologists and pharmacists, psychologists, advanced practice providers, licensed clinical social workers, oncology-certified nurses, and dietitians.


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