Loperamide (sold as Imodium) is the fastest over-the-counter option for stopping diarrhea. In clinical trials, it controlled symptoms significantly faster than bismuth subsalicylate (Pepto-Bismol) and reduced the number of unformed stools within the first 24 hours. But medication is only one piece. What you eat, drink, and avoid in the hours after symptoms start all affect how quickly you recover.
Loperamide vs. Bismuth Subsalicylate
These are the two main OTC medications for acute diarrhea, and they work differently. Loperamide slows the muscle contractions in your intestines, giving your body more time to absorb water from stool. The result is firmer stools and fewer trips to the bathroom. In a head-to-head comparison, loperamide provided faster relief and kept diarrhea under control for longer periods than bismuth subsalicylate at standard doses.
Bismuth subsalicylate works by reducing inflammation in the gut lining and has mild antibacterial properties. It’s a reasonable choice for milder symptoms or when diarrhea comes with nausea, since it helps settle the stomach too. But if speed is your priority, loperamide is the stronger option.
There are situations where you should not take loperamide. The FDA specifically warns against using it when diarrhea comes with a high fever (above 102°F), blood or black color in the stool, or when symptoms are caused by certain bacterial infections like Salmonella or C. diff. In these cases, diarrhea is your body’s way of flushing out the infection, and slowing that process down can make things worse. Loperamide is also not recommended for children under 2 years old.
Hydration Matters More Than You Think
Diarrhea pulls water and essential minerals out of your body fast. Even if your stools improve quickly, dehydration can leave you feeling weak, dizzy, and nauseous for much longer than necessary. Replacing fluids is not optional during a bout of diarrhea.
Plain water alone isn’t ideal because it doesn’t replace the sodium and potassium you’re losing. Oral rehydration solutions like Pedialyte or Oralyte contain a precise balance of sugar, sodium, potassium, and citrate that helps your intestines absorb fluid more efficiently. These work better than sports drinks like Gatorade, which tend to have too much sugar and not enough sodium for true rehydration. If you can’t get a rehydration solution, sipping broth is a decent backup since it contains both sodium and water.
What to Eat (and What to Skip)
The classic BRAT diet (bananas, rice, applesauce, toast) is fine for the first day or two, but there’s no reason to limit yourself to just those four foods. Any bland, easy-to-digest food will work. Good options include brothy soups, oatmeal, boiled potatoes, crackers, and unsweetened dry cereals. As your stomach settles, adding foods with actual nutritional value helps your body recover faster: cooked carrots, sweet potatoes without skin, avocado, skinless chicken or turkey, fish, and eggs all provide protein and nutrients without irritating your gut.
What you avoid matters just as much as what you eat. These foods and drinks tend to make diarrhea worse or last longer:
- Caffeine and alcohol, which both speed up intestinal contractions
- Dairy products, including milk, yogurt, cheese, and ice cream
- Sugary foods like candy, cakes, and desserts
- Fried and greasy foods
- Acidic foods like citrus, tomato sauce, and vinegar-based dressings
- High-fiber roughage like leafy greens, fruit skins, popcorn, nuts, seeds, and beans
Soluble Fiber Can Help Firm Things Up
This sounds counterintuitive, since most people associate fiber with loosening stools. But soluble fiber, particularly psyllium husk, forms a gel when mixed with water. That gel slows down intestinal movement when things are moving too fast, which is exactly what happens during diarrhea. It essentially acts as a natural thickener for loose stool.
The effective dose in studies is around 25 grams per day (about 5 teaspoons), taken with plenty of water, roughly 500 mL per dose. Starting with a smaller amount and building up is more practical for most people, especially if your stomach is already upset. Psyllium is widely available as a powder you mix into water. Just make sure you’re drinking enough fluid alongside it, since psyllium absorbs a large amount of water and could worsen dehydration if you don’t compensate.
Probiotics for Shorter Recovery
Probiotics won’t stop diarrhea in its tracks the way loperamide does, but they can shorten how long an episode lasts. The best-studied strain for acute diarrhea is Saccharomyces boulardii, a beneficial yeast rather than a bacterium. In clinical trials, people taking it recovered in about 3.6 days compared to 4.8 days without it. That’s roughly a full day shaved off recovery time.
S. boulardii is available over the counter in capsule form. It’s most useful when diarrhea is caused by an infection or follows a course of antibiotics. Starting it early in the illness gives the best results.
Diarrhea in Children
The rules change significantly for kids. Anti-diarrheal medications like loperamide and bismuth subsalicylate should not be given to young children with acute diarrhea. International pediatric guidelines are clear on this: these drugs don’t prevent dehydration or improve nutrition, and some carry risks of serious side effects in small children.
The priority for children is preventing dehydration with oral rehydration solutions and continued feeding. Zinc supplementation is also recommended: 10 mg per day for infants under 6 months and 20 mg per day for older children, continued for 10 to 14 days. The tablet can be dissolved in a small amount of clean water or breast milk for infants. For children, watch for diarrhea lasting more than 24 hours without improvement, fever above 102°F, or blood in the stool, all of which need medical evaluation.
Signs That Diarrhea Needs Medical Attention
Most acute diarrhea resolves within a few days on its own or with the strategies above. But certain warning signs mean something more serious may be going on. For adults, these include diarrhea lasting more than two days with no improvement, a fever above 102°F, and stools that are bloody or black. For children, the threshold is lower: seek care if diarrhea doesn’t improve within 24 hours or if any of those same red flags appear. Signs of significant dehydration, like very dark urine, dizziness when standing, or no tears when a child cries, also warrant prompt attention.