For most cases of acute diarrhea, a combination of oral rehydration, the right over-the-counter medication, and gentle food choices will resolve symptoms within one to three days. The two main OTC options are loperamide (sold as Imodium) and bismuth subsalicylate (the active ingredient in Pepto-Bismol), and each works differently depending on your situation.
Loperamide: The Fastest Symptom Relief
Loperamide is the most effective OTC option for slowing down frequent, watery stools. It works by reducing the speed at which your intestines push food through, giving your body more time to absorb water. It also tightens the anal sphincter, which directly helps with the urgency that makes diarrhea so disruptive.
The standard adult dose is two capsules (4 mg) to start, then one capsule (2 mg) after each loose stool, up to a maximum of 16 mg (eight capsules) in a day. Most people find their symptoms improve within hours of the first dose. For children between 2 and 12, dosing is based on weight and age, so check the package carefully or ask a pharmacist.
One important rule: don’t take loperamide if you have a fever or blood in your stool. In those cases, your body may be trying to flush out a bacterial infection, and slowing that process down can make things worse.
Bismuth Subsalicylate for Milder Symptoms
Bismuth subsalicylate (Pepto-Bismol, Kaopectate) is a gentler option that also helps with the nausea and cramping that often come alongside diarrhea. It works by coating the lining of your stomach and intestines, reducing inflammation and limiting the amount of fluid your gut secretes. It’s a solid choice for traveler’s diarrhea or mild stomach bugs where you’re uncomfortable but not housebound.
Because it contains a salicylate (the same family of compounds as aspirin), it should not be given to anyone under 16. In rare cases, salicylates can trigger a serious condition called Reye’s syndrome in children, which causes dangerous brain swelling. Adults taking blood thinners should also avoid it. And don’t be alarmed if your tongue or stool turns black temporarily; that’s a harmless side effect of the bismuth.
Rehydration Matters More Than You Think
The biggest risk from diarrhea isn’t the diarrhea itself. It’s dehydration. Every loose stool pulls water and essential salts out of your body, and if you’re not replacing them, you can quickly end up feeling dizzy, exhausted, and far sicker than the original bug warrants.
Oral rehydration solutions (like Pedialyte or store-brand equivalents) are the gold standard because they contain the right ratio of sugar, sodium, and potassium to help your intestines absorb water efficiently. Plain water is better than nothing, but it doesn’t replace lost electrolytes. Sports drinks work in a pinch, though they contain more sugar than ideal. Avoid coffee, alcohol, and sugary sodas, all of which can pull more water into your intestines and make diarrhea worse.
For young children, the World Health Organization recommends zinc supplementation alongside rehydration: 20 mg per day for 10 to 14 days (10 mg per day for infants under six months). Zinc shortens the duration of diarrhea episodes and reduces their severity. This recommendation is especially relevant in developing countries where diarrhea-related dehydration is a leading cause of childhood illness, but it’s worth discussing with your pediatrician regardless of where you live.
What to Eat (and What to Skip)
You may have heard of the BRAT diet: bananas, rice, applesauce, and toast. It was the standard advice for decades, but it’s no longer recommended as a strict protocol. The American Academy of Pediatrics specifically advises against it for children because it lacks protein, calcium, vitamin B12, and fiber, and sticking to it for more than 24 hours can actually slow recovery by depriving the gut of the nutrients it needs to heal.
The current guidance is simpler: eat as tolerated. Start with bland, soft foods if that’s all your stomach can handle, but move back to a normal diet as soon as you feel up to it. Good early choices include plain rice, boiled potatoes, crackers, chicken broth, and baked chicken. Avoid greasy, spicy, or heavily seasoned foods until your gut settles. Dairy can be tricky because diarrhea sometimes temporarily reduces your ability to digest lactose, so if milk makes things worse, hold off for a few days.
Probiotics: Helpful but Strain-Specific
Probiotics can shorten a bout of diarrhea, but the benefit depends heavily on which strain you take. Lactobacillus rhamnosus GG is the best-studied strain for acute diarrhea, with clinical trials showing it reduces diarrhea duration by roughly 19 hours compared to no treatment. Saccharomyces boulardii, a beneficial yeast sold under brand names like Florastor, is commonly recommended as well, though clinical data on its effectiveness has been more mixed.
If you want to try a probiotic, look for products that list specific strains on the label rather than just genus names. Take them alongside your other treatments, not instead of rehydration or medication. They’re generally safe for most adults and older children, but people with compromised immune systems should check with a doctor first.
When Diarrhea Needs More Than OTC Treatment
Most diarrhea clears up on its own within a few days. But certain signs suggest something more serious is going on. Seek medical attention if you notice blood in your stool, a persistent fever, severe abdominal pain, or if diarrhea lasts more than a few days without improvement. Waking up at night specifically because of diarrhea (rather than just having it during the day) and unintentional weight loss are also warning signs that point toward something beyond a simple stomach bug.
Some groups are at higher risk for complications: adults over 65, pregnant women, anyone with a weakened immune system, and people who recently took antibiotics. Antibiotic use is a particularly important detail to mention to your doctor, because up to 85% of patients with C. difficile infections (a serious, sometimes dangerous cause of diarrhea) report antibiotic exposure within the previous 28 days. If your diarrhea started during or shortly after a course of antibiotics, that changes the treatment approach entirely.
Bacterial infections like Salmonella, Shigella, and Campylobacter sometimes require prescription antibiotics, but your doctor will only prescribe them after confirming what’s causing the problem. Taking antibiotics for viral diarrhea does nothing and can increase your risk of future antibiotic-resistant infections.