For a standard upset stomach with diarrhea, two over-the-counter options cover most cases: bismuth subsalicylate (the active ingredient in Pepto-Bismol) treats both nausea and diarrhea together, while loperamide (Imodium) targets diarrhea specifically and works faster. Which one to reach for depends on whether your main problem is the stomach discomfort, the diarrhea, or both.
Best OTC Options for Stomach and Diarrhea
Bismuth subsalicylate is the go-to when you have the full package: nausea, cramping, and loose stools. It coats the stomach lining and reduces inflammation in the gut, which is why it helps with that queasy, churning feeling alongside diarrhea. It comes as a liquid or chewable tablet and can be dosed every 30 minutes to an hour as symptoms continue.
Loperamide is a better choice when diarrhea is the dominant symptom. It slows the movement of your intestines, giving your body more time to absorb water from stool. In a head-to-head comparison of the two medicines in adults with acute diarrhea, loperamide significantly reduced the number of unformed bowel movements and maintained control of symptoms longer than bismuth subsalicylate. If you’re dealing with frequent, watery trips to the bathroom and need relief fast, loperamide is the stronger option. The maximum OTC dose for adults is 8 mg per day.
If your upset stomach leans more toward heartburn or acid indigestion without much diarrhea, a simple antacid (like calcium carbonate) provides the quickest relief. For acid that keeps returning, H2 blockers start working within one to three hours and suppress acid for several hours. Proton pump inhibitors are not meant for immediate relief and can take one to four days for full effect, so they’re only useful for recurring heartburn, not a sudden bout of stomach trouble.
What Not to Give Children
Bismuth subsalicylate should not be used in children younger than 12. It contains a salicylate, the same class of compound found in aspirin, and children are more sensitive to its effects, particularly when they already have a fever or have lost fluids from vomiting and diarrhea. In children recovering from the flu or chickenpox, salicylates carry a risk of Reye’s syndrome, a rare but serious condition affecting the brain and liver. If a child develops nausea or vomiting during these illnesses, that warrants a call to their pediatrician rather than an OTC remedy.
For children with diarrhea, the priority is fluid replacement rather than medication. If a child’s diarrhea hasn’t improved within 24 hours, or they develop a fever above 102°F, bloody stools, or signs of dehydration like no wet diapers for three or more hours, they need medical attention.
Fluids Matter More Than Medicine
No pill or liquid will help much if you’re not replacing what you’re losing. Diarrhea pulls water and electrolytes out of your body quickly, and dehydration is the main reason a simple stomach bug turns into something that lands people in urgent care. Signs you’re getting dehydrated include excessive thirst, dry mouth, dark urine, dizziness, and weakness.
Water alone isn’t ideal because it doesn’t replace the sodium and potassium you’re losing. Oral rehydration solutions, available at any pharmacy, are formulated with a specific balance of sugar and salt that helps your intestines absorb fluid efficiently. The sugar acts as a carrier that pulls sodium (and water along with it) across the intestinal wall. If you don’t have a commercial rehydration solution on hand, broth, diluted juice, or sports drinks can bridge the gap, though they’re not as precisely balanced.
Probiotics Can Shorten Recovery
One supplement with solid evidence behind it is Saccharomyces boulardii, a beneficial yeast available over the counter. In a controlled study of patients with acute watery diarrhea, those taking S. boulardii alongside standard rehydration recovered in an average of 3.6 days compared to 4.8 days in the group that didn’t take it. That’s roughly a full day shaved off the illness. Even more interesting, the probiotic group had about half as many diarrhea episodes over the following two months, suggesting it helps restore gut balance beyond the immediate illness.
S. boulardii is found in products like Florastor. It’s different from bacterial probiotics because, as a yeast, it isn’t killed by antibiotics, making it useful if you end up needing antibiotic treatment for your symptoms.
Eating While Your Gut Recovers
The old advice to eat only bananas, rice, applesauce, and toast (the BRAT diet) is fine for the first day or two, but it’s nutritionally limited and there’s no research showing it speeds recovery compared to simply eating bland foods more broadly. Once your stomach starts to settle, you can expand to cooked carrots, butternut squash, sweet potatoes without skin, avocado, skinless chicken or turkey, fish, and eggs. These are all easy to digest but provide the protein and nutrients your body needs to actually recover.
Avoid dairy, fried foods, caffeine, and alcohol until your stools normalize. These can all irritate an already inflamed gut or pull more water into your intestines, making diarrhea worse.
Drug Interactions to Watch For
Loperamide is processed by the liver and can interact with a surprisingly long list of medications. If you take heart rhythm drugs like amiodarone or verapamil, the seizure medications carbamazepine or phenytoin, the antibiotic clarithromycin, or HIV medications like ritonavir, loperamide levels in your body can be affected in ways that increase side effects. People with liver problems should also be cautious, since impaired liver function changes how the drug is broken down. If you’re on multiple medications, check with a pharmacist before taking loperamide.
Bismuth subsalicylate has its own interaction profile. Because it contains a salicylate, it can amplify the effects of blood thinners and shouldn’t be combined with aspirin. It can also interfere with certain arthritis medications and some diabetes drugs.
When Symptoms Point to Something Bigger
Most stomach bugs resolve within two to three days. If your diarrhea persists beyond two days without any improvement, or you notice blood or black color in your stool, those are signals that something more than a routine virus may be going on. Severe abdominal pain, signs of dehydration that aren’t improving with fluids, and high fever all warrant medical evaluation.
Traveler’s diarrhea, in particular, sometimes requires prescription antibiotics. For moderate to severe cases, especially when acquired in regions with high rates of antibiotic-resistant bacteria like Southeast Asia, doctors typically prescribe a short course of targeted antibiotics. These are most effective when started early, which is why frequent travelers are sometimes given a prescription to carry with them. Loperamide can be used alongside antibiotics to manage symptoms while the medication works.