Two over-the-counter medications handle most cases of acute diarrhea: loperamide (sold as Imodium) and bismuth subsalicylate (sold as Pepto-Bismol). They work differently, and the right choice depends on your symptoms and what’s causing the problem. Probiotics and simple dietary adjustments can also help, especially alongside medication.
Loperamide: The Go-To for Frequent Loose Stools
Loperamide slows the movement of your bowel and reduces the flow of fluids into your intestines, which means fewer trips to the bathroom and firmer stools. It’s the most effective OTC option for stopping diarrhea quickly. The maximum over-the-counter dose for adults is 8 mg per day. Most products come in 2 mg capsules or tablets, so that’s a maximum of four in 24 hours.
There are situations where you should not take loperamide. If you have bloody stool with a fever, those can be signs of a bacterial infection that your body needs to clear, and slowing your gut down could make things worse. You should also avoid it if your diarrhea started after a course of antibiotics, since antibiotic-associated diarrhea can involve dangerous bacteria. People having an inflammatory bowel disease flare-up (ulcerative colitis or Crohn’s) should skip it as well.
Bismuth Subsalicylate: Better for Nausea and Mild Cases
Bismuth subsalicylate takes a different approach. It coats the walls of your digestive tract and binds to bacteria or toxins so they pass out in your stool. It also reduces inflammation in the intestine and limits fluid loss. This makes it a solid choice when your diarrhea comes with nausea, cramping, or general stomach upset, since it treats multiple symptoms at once.
Two quirks to know: it can temporarily turn your tongue dark and make your stools look grayish-black. Both are harmless and go away once you stop taking it. However, bismuth subsalicylate contains a compound related to aspirin, so it should not be given to children or teenagers who have or are recovering from the flu or chickenpox due to the risk of Reye’s syndrome.
Probiotics as a Supplement to Treatment
Probiotics won’t stop diarrhea as fast as loperamide, but they can shorten how long it lasts. They work by replenishing the beneficial bacteria in your gut. A large meta-analysis of randomized trials in children found that Saccharomyces boulardii reduced diarrhea duration by about 1.25 days compared to placebo and cut the risk of diarrhea lasting two or more days by roughly 78%. Lactobacillus reuteri showed similar results, reducing duration by about 0.84 days. Lactobacillus GG (often labeled LGG) also shortened recovery time.
These findings were strongest in children, but probiotics are widely used by adults too. You can take them alongside loperamide or bismuth subsalicylate. Look for products containing Saccharomyces boulardii or Lactobacillus strains, as these have the most evidence behind them.
What to Eat (and What to Skip)
You may have heard of the BRAT diet: bananas, rice, applesauce, and toast. It used to be standard advice, but it’s no longer recommended as a strict regimen. It lacks calcium, vitamin B12, protein, and fiber, and following it for more than a day or two can actually slow your recovery. The American Academy of Pediatrics specifically advises against it for children because the nutritional gaps can delay gut healing.
Instead, eat soft, bland foods when you can tolerate them, then return to a normal, balanced diet as soon as you feel up to it. Your body needs nutrients to recover. The priority during diarrhea is staying hydrated. Water, broth, and oral rehydration solutions all work. Avoid caffeine and alcohol, which can worsen dehydration.
Traveler’s Diarrhea
If you’re traveling internationally and develop diarrhea, the approach depends on severity. Mild cases respond well to loperamide or bismuth subsalicylate alone. Moderate to severe cases, especially with fever or bloody stool, typically call for prescription antibiotics. Many travel medicine doctors prescribe antibiotics in advance so you can self-treat if needed. The CDC recommends azithromycin as first-line treatment, particularly in Southeast Asia where other antibiotics face resistance. Loperamide can be combined with antibiotics for faster relief but should not be used alone when you have fever or bloody diarrhea.
When Prescription Medication Is Needed
If OTC options aren’t enough, doctors can prescribe stronger medications that work similarly to loperamide but at higher doses or through different mechanisms. These are reserved for severe diarrhea and are used alongside fluid and electrolyte replacement. Prescription options are not appropriate when diarrhea is caused by an active infection, since trapping bacteria in the gut can be harmful.
Signs That Need Medical Attention
Most diarrhea resolves within a day or two, but certain symptoms signal something more serious. For adults, contact a doctor if diarrhea lasts more than two days, if you’re passing six or more loose stools per day, or if you notice blood, pus, or black tarry stools. Severe abdominal pain, frequent vomiting, or high fever also warrant a call.
For children, the timeline is shorter: diarrhea lasting more than one day needs medical attention, and any fever in infants is a red flag. Watch for signs of dehydration in both adults and children: extreme thirst, dark urine, urinating much less than usual, dizziness, or feeling unusually tired. In infants, no wet diapers for three or more hours, no tears when crying, or a sunken soft spot on the skull are urgent warning signs.