What to Eat After Diarrhea During Treatment

The diarrhea has stopped, or at least slowed. You are wrung out, and you are hungry for the first time in a day. What you eat in the next few hours decides whether the gut settles or starts again.

The rule is simple: go back in stages, and start with liquid. What follows is the order most oncology guidance uses, with the reasons attached.

The NCI booklet Eating Hints suggests drinking only clear liquids for 12 to 14 hours after a bout of diarrhea. Clear means you can see through it.

Its general clear-liquid list: water, weak caffeine-free tea, clear carbonated drinks, fruit-flavored drinks, sports drinks, bouillon, clear fat-free broth, gelatin, popsicles, and fruit ices made without fruit pieces or milk. Clear apple juice is on that list too, but the same booklet's diarrhea section says to avoid apple juice because it is high in sorbitol, so leave that one out for now.

How much matters as much as what. MedlinePlus advises 8 to 10 glasses of clear fluid a day while diarrhea lasts, plus at least one cup after every loose bowel movement. That last rule is the one people skip, and it is the one that keeps you out of the infusion chair.

Diarrhea strips out sodium and potassium along with fluid. Water alone puts back one of the three.

NCI advises clear liquids such as water or broth to replace both fluids and electrolytes, and notes that room temperature liquids are easiest on the stomach. Eating Hints points to drinks with sodium and potassium in them, naming bouillon, fat-free broth, and sports drinks such as Gatorade or Propel.

Food carries electrolytes too. NCI names peeled and boiled potatoes, soup, bananas, applesauce, and crackers.

Oral rehydration solution is a stronger option, and it is worth knowing about before you need it. NIDDK explains that these solutions contain glucose as well as electrolytes, and can be bought ready-made or mixed at home. The same source adds an important caution: people with a weakened immune system, older adults, and people with diabetes or kidney disease should talk with a doctor before drinking them. That covers most people in cancer treatment, so ask in advance.

Bananas, rice, applesauce, toast. The acronym is decades old, and its logic holds up better than its name.

Every item on that list is low in fiber, bland, starchy, and easy to absorb. Bananas and potatoes bring potassium back. None of them ask much of an irritated bowel.

What BRAT gets wrong is stopping there. Four foods will not carry you for long, and they bring almost no protein. NIDDK puts it plainly: when your appetite returns, you can most often go back to your normal diet even if you still have some diarrhea. So treat BRAT as the first rung, not the whole ladder.

NCI publishes an actual low-fiber list for people with diarrhea from cancer or its treatment, and it is broader than four foods.

• Mains: skinless baked, broiled, or grilled chicken or turkey, fish, eggs, white bread, white rice, noodles, peeled potatoes, cooked refined cereals
• Fruit and vegetables: cooked carrots, cooked string beans, mushrooms, canned peaches, canned pears, applesauce, fruit juice, vegetable juice
• Snacks and sweets: saltines, graham crackers, animal crackers, ginger snaps, vanilla wafers, angel food cake, custard, gelatin, sherbet, sorbet, yogurt
• Fats: butter, oil, mayonnaise, salad dressing without seeds

MedlinePlus adds a sense of scale. A prescribed low-fiber diet often caps intake at something like 10 to 15 grams of fiber a day, with your own number set by your provider or dietitian. Off the list go beans and legumes, whole grains, most raw fruit and vegetables, all skins, nuts and seeds, and the tough connective tissue in meat.

Not all fiber behaves the same way, which is why blanket advice about fiber confuses people.

MedlinePlus describes soluble fiber as fiber that attracts water and turns to gel during digestion, which slows digestion down. Insoluble fiber does the opposite: it adds bulk and appears to speed food through the stomach and intestines.

When stool is loose, the gel-forming kind is the one you want. The catch is that many soluble fiber foods, such as beans, lentils, nuts, and seeds, are also off-limits on a low-fiber plan. That leaves a narrow but useful set: oatmeal, bananas, and applesauce all appear on the diarrhea food lists above.

Powdered soluble fiber supplements are widely used for this, but do not start one on your own. Ask your team whether it fits your situation and your medicines.

NCI's list of things to avoid during diarrhea: alcohol, milk and dairy products, spicy foods, caffeinated drinks, dried beans, high-fat foods, fruit juices, and sugar-free gum or candies.

MedlinePlus adds fried and greasy foods, carbonated drinks, and the gas-producing vegetables: broccoli, peppers, beans, and corn. It suggests dropping dairy only if it seems to make your symptoms worse.

Once ordinary food is staying down, the problem flips. A few days of clear liquids and white toast leaves you short on protein at exactly the moment your body is repairing gut lining.

Add protein back gently: eggs, skinless chicken, fish, plain yogurt, smooth peanut butter on white bread. Eat small and often rather than sitting down to one large plate. Keep the fluids going for another day after stools normalize.

Food safety deserves an extra look here, since your gut is already irritated and treatment lowers your infection defenses. Refrigerate perishable food within 2 hours, or 1 hour above 90°F. Reheat leftovers to 165°F. Eating Hints specifically says to skip leftover rice, and to eat refrigerated leftovers within 3 days.

Call your oncology team the same day if:

• You have seven or more bowel movements a day above your usual number. NCI grades this as severe and says it can be life-threatening.
• Diarrhea has continued past 24 hours. Eating Hints says to contact your doctor at that point.
• Your temperature reaches 100.4°F (38°C) or higher. With low white blood cells this is an emergency.
• You cannot keep fluids down for 24 hours, or you are barely passing urine.
• There is blood or mucus in the stool, or the stool looks black.
• You feel dizzy or lightheaded when standing.

Two warnings about over-the-counter antidiarrheal medicine, both from NIDDK. Do not take one if you have bloody stools or a fever. And see a doctor if the diarrhea gets worse or lasts more than 2 days while you are taking it.

• Which of my treatments or medicines is driving this, and can anything be changed?
• Do you want me on a specific low-fiber plan, and for how many days?
• Is an antidiarrheal medicine safe for me, and what dose?
• Should I be using an oral rehydration solution instead of sports drinks?
• Would a soluble fiber supplement help in my case?
• What number of stools in a day means I call you rather than wait?

Read next: Managing Diarrhea During Cancer Treatment, Staying Hydrated During Cancer Treatment, Fiber During Cancer Treatment: What to Ask, Food and Fluid Plan for Chemo Day, and Food Safety During Cancer Treatment.

• https://www.cancer.gov/publications/patient-education/eatinghints.pdf
• https://www.cancer.gov/about-cancer/treatment/side-effects/diarrhea
• https://www.cancer.gov/about-cancer/treatment/side-effects/nutrition/low-fiber-foods
• https://www.niddk.nih.gov/health-information/digestive-diseases/diarrhea/treatment
• https://medlineplus.gov/ency/patientinstructions/000121.htm
• https://medlineplus.gov/ency/patientinstructions/000200.htm
• https://medlineplus.gov/ency/article/002470.htm
• https://www.foodsafety.gov/keep-food-safe/4-steps-to-food-safety
• https://www.cancer.gov/about-cancer/treatment/side-effects/infection