For most cases of acute diarrhea, over-the-counter medications like loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol) can provide relief within hours. But the single most important thing you can take is fluids, because dehydration is the real danger with diarrhea, not the diarrhea itself. What works best depends on the cause, your age, and how severe your symptoms are.
Over-the-Counter Medications
Loperamide is the most widely used anti-diarrheal. It works by slowing down the movements of your intestines, giving your body more time to absorb water from stool. The standard approach for adults is to take two capsules (4 mg) after the first loose bowel movement, then one capsule (2 mg) after each subsequent one. The maximum is 8 capsules (16 mg) in 24 hours for prescription use, or 4 tablets (8 mg) per day for over-the-counter versions. Most people notice improvement within the first few doses.
Bismuth subsalicylate is the other major option. It coats the lining of the gut and can help with both diarrhea and the nausea that sometimes accompanies it. Because it contains a salicylate (the same class of compound found in aspirin), it comes with a few important cautions. Don’t give it to children or teenagers who have or are recovering from the flu or chickenpox, as it carries a risk of Reye’s syndrome. If you already take aspirin, blood thinners, or other salicylate-containing medications, check labels carefully to avoid stacking doses. People with gout or bleeding disorders should also steer clear.
Loperamide is generally the better choice if your main goal is simply stopping frequent trips to the bathroom. Bismuth subsalicylate is more useful when you’re also dealing with an upset stomach. Neither should be used if you have a high fever or bloody stools, which can signal an infection that your body needs to fight off rather than slow down.
Fluids and Rehydration
Replacing lost fluids matters more than stopping the diarrhea. Every loose bowel movement pulls water and electrolytes out of your body, and if you’re losing more than you’re drinking, dehydration sets in fast. Early signs include excessive thirst, dry mouth, dark urine, dizziness, and weakness.
For mild cases, water, broth, and diluted juice work fine. For anything more persistent, oral rehydration solutions (sold as Pedialyte, DripDrop, or generic equivalents) are far more effective than water alone. The WHO-recommended formula contains a precise mix of glucose, sodium chloride, and potassium chloride designed to maximize absorption. You can also make a basic version at home with clean water, salt, and sugar, though commercial products are more reliable. Sports drinks are a common substitute but contain more sugar and less sodium than ideal.
For young children and infants, rehydration is the first priority. Breast milk or formula should continue during diarrhea episodes. The WHO recommends oral rehydration solution paired with a 10 to 14 day course of zinc supplements, which shortens the duration of diarrhea and improves recovery in children.
Probiotics That Actually Help
Not all probiotics are created equal when it comes to diarrhea. A large meta-analysis of randomized controlled trials found that Saccharomyces boulardii, a beneficial yeast, was the most effective probiotic for acute diarrhea. It shortened symptom duration by about 1.25 days compared to placebo and reduced the risk of diarrhea lasting two or more days by roughly 78%. Lactobacillus reuteri showed similar benefits, cutting duration by about 0.84 days.
Multi-strain combinations containing Lactobacillus, Bifidobacterium, and Saccharomyces species also performed well, reducing duration by about 1.2 days. Interestingly, Lactobacillus rhamnosus GG, one of the most commonly marketed probiotic strains, reduced diarrhea duration compared to no treatment but showed no clear benefit over placebo, which is a meaningful distinction.
If you’re going to try a probiotic, look specifically for Saccharomyces boulardii on the label. It’s available over the counter under brand names like Florastor. Start taking it at the onset of symptoms for the best effect.
What to Eat (and What to Skip)
The old advice to stick to bananas, rice, applesauce, and toast (the BRAT diet) is no longer the standard recommendation. The National Institute of Diabetes and Digestive and Kidney Diseases notes that most experts don’t recommend following a restricted diet or fasting during acute diarrhea. Once you feel like eating, you can return to your normal diet. Children should eat their usual age-appropriate foods.
That said, common sense still applies. Greasy, spicy, and high-fiber foods tend to make things worse. Dairy can be temporarily harder to digest because diarrhea sometimes disrupts the enzymes that break down lactose. Caffeine and alcohol both speed up gut motility, which is the opposite of what you want. Bland, easy-to-digest foods are a reasonable starting point, but you don’t need to limit yourself to four specific items.
When Antibiotics Are Needed
Most diarrhea is caused by viruses and clears on its own within a few days. Antibiotics don’t help with viral diarrhea and can actually make things worse by disrupting your gut bacteria. But bacterial infections, particularly from contaminated food or water while traveling, sometimes require antibiotic treatment.
The CDC classifies traveler’s diarrhea by severity. Moderate cases (those that disrupt your plans but don’t stop you entirely) can be treated with antibiotics or with loperamide alone, depending on the situation. Severe cases, meaning diarrhea that’s incapacitating or involves blood or fever, call for antibiotic treatment. Azithromycin is the preferred first-line option, especially in Southeast Asia or anywhere antibiotic-resistant bacteria are common. Rifaximin is another option but only works against non-invasive bacterial strains and shouldn’t be used if there’s any suspicion of Salmonella, Shigella, or Campylobacter.
You won’t be prescribing these yourself. The point is knowing that if your diarrhea involves a fever over 102°F, bloody or black stools, or severe abdominal pain, those symptoms suggest something beyond a simple stomach bug.
Red Flags by Age
For adults, diarrhea that doesn’t improve after two days warrants a call to your doctor. So do signs of dehydration: severe weakness, little or no urination, dizziness, or dark-colored urine. A fever above 102°F (39°C), bloody or black stools, and severe abdominal or rectal pain are all reasons to seek prompt medical attention. More than 10 bowel movements a day, or fluid losses that clearly outpace what you’re drinking, qualifies as severe diarrhea.
Children need closer watching because they dehydrate faster. If a child’s diarrhea hasn’t improved within 24 hours, that’s the threshold for medical attention, half the time allowed for adults. Other warning signs include no wet diaper in three or more hours, a fever above 102°F, bloody or black stools, and visible signs of dehydration like sunken eyes, sunken cheeks, or skin that stays pinched when you pull it up and release it.