For most adults with acute diarrhea, loperamide (sold as Imodium) is the fastest-acting option to reduce symptoms. Bismuth subsalicylate (Pepto-Bismol) is a good alternative, especially when nausea or stomach upset accompanies loose stools. Beyond medication, staying hydrated and avoiding certain foods matters just as much as what you take from the pharmacy.
Loperamide: The Go-To for Acute Diarrhea
Loperamide works by slowing the movement of your intestines, giving your body more time to absorb water from stool. It also tightens the anal sphincter, which helps with the urgency that makes diarrhea so disruptive. Most people notice a difference within an hour of taking it.
The standard adult dose is two capsules (4 mg) after the first loose stool, then one capsule after each subsequent loose stool. The maximum is eight capsules (16 mg) in a single day. If your diarrhea hasn’t improved within two days, stop taking it and see a doctor.
Loperamide is not appropriate for every situation. If you have a fever above 102°F or blood in your stool, skip it. These signs suggest an infection that your body needs to clear, and slowing your gut can make things worse. It’s also not safe for children under five. The WHO warns that antimotility drugs like loperamide can be harmful and even fatal in infants if used improperly, because they delay the elimination of infection-causing organisms.
Bismuth Subsalicylate: Better for Infectious Diarrhea
Bismuth subsalicylate, the active ingredient in Pepto-Bismol, takes a different approach. Rather than slowing your gut, it reduces the amount of fluid your intestines secrete, fights bacteria, and calms inflammation. This makes it a better choice when diarrhea comes with nausea, cramping, or the suspicion that something you ate is to blame. It also has direct antibacterial effects against some of the organisms that cause food poisoning and traveler’s diarrhea.
There are some important restrictions. Don’t take it if you’re allergic to aspirin, since the active ingredient is chemically related to aspirin. Avoid it during pregnancy or while breastfeeding. If you take blood thinners like warfarin, it increases bleeding risk. And don’t combine it with aspirin, as this raises the chance of salicylate toxicity, which can show up as ringing in the ears or easy bruising. Children and teenagers recovering from chickenpox or the flu should also avoid it because of the risk of Reye’s syndrome. It may temporarily turn your tongue and stool black, which is harmless.
Hydration Is the Real Priority
Diarrhea pulls water and electrolytes out of your body fast. When you’re losing more fluid than you’re drinking, dehydration sets in, and that’s what actually makes most people feel terrible. Oral rehydration solutions, which contain a precise balance of salt and sugar, are the single most effective treatment for diarrhea-related dehydration. You can buy premade versions (like Pedialyte or generic equivalents) or mix your own following WHO guidelines.
For mild cases, water, broth, and diluted fruit juice can keep you going. Avoid drinks that can pull more water into your gut and worsen symptoms: regular soda, full-strength fruit juice, and anything with high fructose content. Sports drinks are okay in a pinch but contain more sugar and less sodium than ideal rehydration solutions.
What to Eat (and Avoid) While Recovering
You don’t need to starve yourself or follow a strict BRAT diet (bananas, rice, applesauce, toast). Most experts no longer recommend restrictive diets during acute diarrhea. Eating your normal diet, or close to it, actually helps your gut recover faster. That said, some foods will make things worse.
Sugars are a major trigger. Fructose, found naturally in fruits like peaches, pears, cherries, and apples, stimulates your intestines to release water and electrolytes. More than 40 to 80 grams of fructose per day can cause diarrhea on its own. For reference, a single 16-ounce cola contains close to 30 grams. Artificial sweeteners like sorbitol, mannitol, and xylitol, common in sugar-free gum, candy, and some medications, are even worse offenders.
Other foods to limit while your gut is irritated:
- Dairy products. Lactose in milk, soft cheese, and ice cream is hard to digest even under normal circumstances. Diarrhea can temporarily reduce your ability to break down lactose, compounding the problem.
- Caffeine. Coffee, tea, chocolate, and many sodas speed up your digestive system, which is the opposite of what you need right now.
- Fried and fatty foods. When fats aren’t fully absorbed in the upper gut, they reach the colon and get broken down into fatty acids that trigger fluid secretion.
- High-FODMAP foods. Onions, garlic, beans, lentils, wheat, and rye contain poorly absorbed sugars that can worsen loose stools.
Probiotics: Modest but Real Benefits
Certain probiotics can shorten the duration of acute diarrhea, though they won’t stop it immediately. The yeast probiotic Saccharomyces boulardii has the strongest evidence. In a controlled trial, children taking it recovered in about three days compared to four days in the placebo group. That one-day difference is modest, but it’s consistent across multiple studies. Lactobacillus-based probiotics also show similar small benefits. Probiotics are most useful alongside other treatments, not as a replacement for hydration or medication.
Treating Diarrhea in Children
Children need a different approach than adults. The WHO and UNICEF recommend three things: oral rehydration salts, zinc supplements, and continued feeding. Zinc supplementation at 20 mg per day for 10 to 14 days (10 mg for infants under six months) reduces the severity and duration of diarrhea episodes. This is particularly important in developing countries but is supported by evidence globally.
Over-the-counter antidiarrheal medications designed for adults are generally not safe for young children. Loperamide can be dangerous for children under five. Adsorbent remedies like kaolin and activated charcoal don’t meaningfully reduce fluid loss. Antibiotics are ineffective against most causes of childhood diarrhea and can increase bacterial resistance over time. The priority is always to prevent dehydration, maintain nutrition, and let the illness run its course.
For children, watch closely for signs that need medical attention: diarrhea that doesn’t improve within 24 hours, no wet diapers for three or more hours, fever above 102°F, bloody or black stools, or a sunken appearance around the eyes, cheeks, or abdomen. Skin that stays pinched when you press and release it is a sign of significant dehydration.
Signs That Diarrhea Needs Medical Attention
Most diarrhea resolves on its own within a few days. But certain symptoms mean something more serious is going on. Adults should see a doctor if diarrhea lasts more than two days without improvement, if stools are bloody or black, if fever exceeds 102°F, or if signs of dehydration appear: excessive thirst, dry mouth, little or no urination, dizziness, or dark-colored urine. Severe diarrhea, defined as more than 10 bowel movements a day or fluid losses clearly outpacing what you can drink, is a medical concern at any point.