When you have diarrhea, certain foods, drinks, and even common medications can make things significantly worse. The short list: cut back on greasy foods, dairy, caffeine, alcohol, spicy dishes, high-fiber foods, and anything sweetened with sugar alcohols. But knowing *why* these things cause problems helps you make smarter choices until your gut recovers.
Greasy and High-Fat Foods
Fat is one of the strongest triggers for intestinal contractions. When you eat a high-calorie, greasy meal, your body releases more digestive hormones to break it down. Those hormones stimulate stronger contractions in both your small intestine and colon, a process called the gastrocolic reflex. In a healthy gut, this just keeps things moving. When you already have diarrhea, it pushes loose stool through even faster.
Skip fried foods, fast food, fatty cuts of meat, rich sauces, and buttery dishes until your symptoms settle. Even foods you’d normally tolerate fine, like avocado or cheese, can be too much fat for an irritated gut to handle comfortably.
Dairy Products
Even if you’re not normally lactose intolerant, a bout of diarrhea can temporarily change that. The cells lining your small intestine produce lactase, the enzyme that breaks down the sugar in milk. When those cells are damaged or inflamed from an infection or illness, lactase production drops. This is called secondary lactose intolerance, and it means milk, ice cream, soft cheese, and other high-lactose dairy can cause bloating, cramping, and more diarrhea until your gut heals.
Yogurt is sometimes better tolerated because fermentation breaks down some of the lactose. Hard aged cheeses like cheddar and parmesan contain very little lactose and are less likely to cause problems. But if dairy seems to make things worse, avoid it entirely for a few days and reintroduce it gradually.
Coffee and Alcohol
Coffee speeds up your colon, and this effect has little to do with caffeine. Research shows that both regular and decaffeinated coffee stimulate colonic contractions within minutes of drinking them. Coffee also increases gastric acid and other digestive secretions, which adds more fluid to an already overactive digestive tract. If you’re dealing with diarrhea, even your morning decaf can keep things moving too fast.
Alcohol irritates the gut lining and can pull water into the intestines, worsening loose stools. Beer and wine also contain fermentable sugars that feed gut bacteria and produce gas. Save both coffee and alcohol for when your symptoms have fully resolved.
Spicy Foods
The compound that makes chili peppers hot, capsaicin, binds to pain receptors throughout your digestive tract. These receptors respond to capsaicin the same way they respond to heat, triggering stronger intestinal contractions and speeding up digestion. The result is faster transit, looser stools, and sometimes a burning sensation on the way out because those same pain receptors line the rectum. When your gut is already inflamed, capsaicin adds fuel to the fire.
High-Fiber Foods (Especially Insoluble Fiber)
Fiber is normally a good thing, but the type matters when you have diarrhea. Insoluble fiber, the kind found in whole grains, wheat bran, nuts, seeds, and dried fruits, increases the speed at which food passes through your digestive tract. When your intestines are already irritated, even a normal amount of insoluble fiber can be too much.
Soluble fiber is a different story. Found in oatmeal, bananas, and white rice, it absorbs water and can help firm up loose stools. You don’t need to avoid all fiber, just focus on soluble sources and cut back on raw vegetables, whole wheat bread, bran cereals, and nuts until your gut calms down.
Sugar Alcohols and Artificial Sweeteners
Sugar alcohols are one of the sneakiest causes of diarrhea because most people don’t realize they’re eating them. Sorbitol, xylitol, mannitol, maltitol, and erythritol show up in sugar-free gum, mints, candy, protein bars, and diet drinks. Your body can’t fully digest them, so they sit in your intestines and ferment, drawing water into the bowel and producing gas.
The FDA actually requires products containing sorbitol or mannitol to carry a warning that “excessive consumption can cause a laxative effect.” When you already have diarrhea, even small amounts can make things noticeably worse. Check ingredient labels on anything marketed as “sugar-free” or “no sugar added.”
Common Pain Relievers
If you’re reaching for ibuprofen (Advil, Motrin) or naproxen (Aleve) to manage a fever or body aches that came along with your stomach bug, think twice. These belong to a class of drugs called NSAIDs, and their most common side effects are gastrointestinal. They irritate the stomach and intestinal lining, and in an already inflamed gut, they can worsen diarrhea, cause stomach pain, and in severe cases contribute to erosion of the lining. Acetaminophen (Tylenol) is generally easier on the stomach and a better option while your gut is recovering.
What You Should Eat Instead
You may have heard of the BRAT diet: bananas, rice, applesauce, and toast. While these foods are easy on the stomach, most experts no longer recommend sticking to such a restrictive list. The National Institute of Diabetes and Digestive and Kidney Diseases advises that once you feel like eating, you can return to your normal diet in most cases. Children should continue their usual age-appropriate foods, and infants should keep breastfeeding or having formula.
The practical approach is simple: eat what you can tolerate, lean toward bland and low-fat options, and avoid the specific triggers listed above. White rice, plain chicken, broth, bananas, and cooked carrots are all gentle choices. Small, frequent meals tend to sit better than large ones because they trigger a milder gastrocolic reflex.
Staying Hydrated Matters More Than Food
What you drink during diarrhea matters at least as much as what you eat. Every loose stool pulls water and electrolytes out of your body, and dehydration is the main danger of prolonged diarrhea. Water alone isn’t enough if you’re losing a lot of fluid. Oral rehydration solutions, diluted broths, and electrolyte drinks help replace sodium and potassium.
Avoid sugary sodas and fruit juices with high fructose content. The excess sugar can pull more water into the intestines through the same osmotic effect that makes sugar alcohols problematic. If plain water is all you have, sipping it steadily throughout the day is better than drinking large amounts at once.
Signs That Need Medical Attention
Most diarrhea resolves on its own within a couple of days. But certain symptoms signal something more serious. For adults, seek care if diarrhea lasts more than two days without improvement, you develop a fever above 102°F, you see blood or black color in your stool, or you notice signs of dehydration like dark urine, dizziness, excessive thirst, or very little urination.
For children, the timeline is shorter. Diarrhea that doesn’t improve within 24 hours, no wet diaper in three or more hours, a sunken appearance around the eyes or cheeks, or skin that stays “tented” when pinched are all reasons to get medical help promptly. Severe diarrhea, defined as more than 10 bowel movements a day or fluid loss that clearly exceeds what someone is drinking, warrants urgent attention at any age.