The fastest over-the-counter option for stopping diarrhea is loperamide (sold as Imodium), which slows intestinal movement and can reduce symptoms within an hour. Bismuth subsalicylate (Pepto-Bismol) is another common choice that works more gently. Beyond those two standbys, what you should take depends on the cause, how long it’s lasted, and whether you’re dealing with certain warning signs.
Loperamide: The Fastest OTC Option
Loperamide works by slowing down the muscles in your intestines, giving your body more time to absorb water from food and stool. The standard approach for adults is to take two tablets (4 mg) after the first loose bowel movement, then one tablet (2 mg) after each subsequent loose stool. The maximum depends on the formulation: up to 8 capsules (16 mg) per day for the prescription-strength version, or 4 tablets (8 mg) per day for the standard over-the-counter product.
Loperamide is not appropriate in every situation. If you have a high fever or blood in your stool, these can be signs of a bacterial infection like dysentery, and slowing your gut down can trap the infection inside. In those cases, your body is using diarrhea as a defense mechanism, and suppressing it can make things worse. Stick to loperamide only for uncomplicated, watery diarrhea.
Bismuth Subsalicylate: A Gentler Alternative
Bismuth subsalicylate, the active ingredient in Pepto-Bismol and Kaopectate, can ease diarrhea along with nausea and stomach upset. It’s a milder option than loperamide and works well for traveler’s diarrhea and general stomach bugs.
The important thing to know is that bismuth subsalicylate contains a compound related to aspirin. That means you should avoid it if you have a bleeding disorder, stomach ulcers, kidney disease, gout, or an aspirin allergy. It’s also off-limits for children under 12, and children or teenagers recovering from the flu or chickenpox should not take it due to the risk of Reye’s syndrome. If you’re already taking aspirin or any other salicylate-containing product, combining it with bismuth subsalicylate can push you toward an overdose.
Probiotics Can Shorten an Episode
Probiotics won’t stop diarrhea as quickly as loperamide, but they can meaningfully shorten how long it lasts. A large Cochrane review of clinical trials found that probiotics reduced the average duration of diarrhea by about 30 hours and lowered the risk of diarrhea persisting past three days by roughly a third.
Not all probiotic strains are equally useful. The ones with the strongest evidence for diarrhea are Lactobacillus rhamnosus GG (often labeled LGG) and the yeast Saccharomyces boulardii. LGG appeared particularly effective against rotavirus diarrhea in children, reducing stool frequency to nearly zero by day three compared to an average of two loose stools per day in the control group. Saccharomyces boulardii is widely available as a supplement (Florastor is a common brand). Look for products listing one of these specific strains rather than a generic “probiotic blend.”
Hydration Matters More Than Food Choices
The biggest immediate risk from diarrhea isn’t the diarrhea itself. It’s dehydration. Replacing lost fluids and electrolytes is the single most important thing you can do, regardless of what else you take. Water alone isn’t ideal because you’re also losing sodium and potassium. Oral rehydration solutions (like Pedialyte or Drip Drop) are designed for exactly this purpose. Broth, diluted fruit juice, and coconut water can also help.
You may have heard of the BRAT diet (bananas, rice, applesauce, toast) as a go-to for diarrhea. It’s a popular recommendation, but no clinical trials have ever tested whether it actually works. What research does show is that resuming a normal, balanced diet as soon as possible leads to shorter illness, lower stool output, and better nutritional recovery compared to restrictive diets. The BRAT diet provides roughly 300 fewer calories per day than a normal toddler’s diet and is extremely low in fat, fiber, and protein. Eating bland foods is fine if that’s all you can tolerate, but there’s no reason to limit yourself to only those four foods.
Prescription Antibiotics for Traveler’s Diarrhea
Most diarrhea is caused by viruses and resolves on its own. But traveler’s diarrhea caused by certain bacteria can be treated with a prescription antibiotic. Rifaximin is FDA-approved specifically for traveler’s diarrhea caused by non-invasive E. coli strains, taken three times a day for three days. It works locally in the gut and isn’t absorbed much into the bloodstream.
Like loperamide, rifaximin should not be used when diarrhea involves fever or bloody stools, which suggest a more invasive infection that requires a different antibiotic. If symptoms worsen or don’t improve within 24 to 48 hours on rifaximin, that’s a sign the cause is something else entirely.
Zinc for Children
For children with acute diarrhea, the World Health Organization recommends zinc supplementation: 20 mg per day for 10 to 14 days for children over six months, and 10 mg per day for infants under six months. Zinc has been shown to reduce both the duration and severity of diarrhea episodes and helps prevent recurrence in the following weeks. This is particularly relevant in developing countries where zinc deficiency is common, but it’s a safe and inexpensive addition to oral rehydration for any child with persistent diarrhea.
Herbal Remedies Have Limited Evidence
Peppermint oil has some clinical support for reducing gut spasms and slowing gastric motility, which is why it’s sometimes used for irritable bowel syndrome. Enteric-coated peppermint oil capsules (the coating prevents the oil from releasing in your stomach and causing heartburn) have been tested in randomized trials for IBS-related symptoms. Beyond peppermint, very few herbal preparations have been tested in controlled human trials for diarrhea. Many traditional remedies show promise in animal studies, but that’s a long way from proven effectiveness in people.
Signs That Need Medical Attention
Most diarrhea clears up within a couple of days. Certain symptoms, however, signal something more serious. In adults, these include diarrhea lasting more than two days without improvement, bloody or black stools, fever above 102°F (39°C), severe abdominal or rectal pain, and signs of dehydration like excessive thirst, very dark urine, dizziness, or little to no urination.
In children, the timeline is tighter. Seek care if diarrhea doesn’t improve within 24 hours, if there’s no wet diaper in three or more hours, or if the child becomes unusually sleepy or irritable. Physical signs of dehydration in children include sunken eyes or cheeks and skin that stays pinched instead of springing back when released. More than 10 bowel movements a day, or fluid losses clearly outpacing what your child can drink, qualifies as severe diarrhea regardless of other symptoms.