What is the best medicine for upset stomach and diarrhea?

October 7, 2025 •

4 min read

Viral gastroenteritis, a common cause of stomach issues, typically resolves on its own within a few days. While often self-limiting, understanding what is the best medicine for upset stomach and diarrhea can provide faster relief and help manage symptoms effectively.

Quick Summary

This guide explores effective over-the-counter and supportive treatments for upset stomach and diarrhea. Key medications like loperamide and bismuth subsalicylate are reviewed, along with vital hydration strategies and dietary adjustments for relief.

Key Points

Loperamide (Imodium) for Targeted Diarrhea Relief: Use loperamide specifically to slow down intestinal movement and reduce diarrhea frequency.
Bismuth Subsalicylate (Pepto-Bismol) for Multi-Symptom Relief: This medication addresses diarrhea, upset stomach, nausea, and indigestion simultaneously.
Stay Hydrated with Oral Rehydration Solutions (ORS): Counteract dehydration caused by fluid loss with electrolyte-rich solutions like Pedialyte, which are more effective than plain water or sugary drinks.
Stick to a Bland Diet (BRAT): Ease digestive strain by eating gentle foods like bananas, rice, applesauce, and toast while avoiding fatty, spicy foods and dairy.
Know When to See a Doctor: Seek medical advice for prolonged symptoms (more than 48 hours), high fever, bloody stools, or signs of severe dehydration.
Avoid Bismuth Subsalicylate in Children: Do not give bismuth subsalicylate to children or teens recovering from viral illnesses due to the risk of Reye's syndrome.

Understanding the Causes of Upset Stomach and Diarrhea

Identifying the root cause of your symptoms is the first step toward effective treatment. The causes can range from minor issues to more serious underlying conditions.

Common causes include:

Infections: Viral infections like gastroenteritis (stomach flu) and norovirus are frequent culprits. Bacterial infections, often from contaminated food or water (food poisoning), can also cause these symptoms.
Medications: Many prescription and over-the-counter drugs, especially antibiotics, can disrupt the natural balance of gut bacteria, leading to diarrhea.
Food Intolerances: Conditions like lactose intolerance (difficulty digesting the sugar in dairy) or fructose malabsorption can trigger digestive distress.
Digestive Disorders: Chronic issues such as Irritable Bowel Syndrome (IBS), Crohn's disease, or ulcerative colitis often involve recurrent episodes.
Traveler's Diarrhea: Exposure to new bacteria or parasites in unfamiliar regions can cause temporary but significant gastrointestinal upset.

Over-the-Counter Medications for Symptom Relief

For mild to moderate cases, several over-the-counter (OTC) medications can provide relief. The two most common types are loperamide and bismuth subsalicylate, which work through different mechanisms.

Loperamide (Imodium)

Loperamide primarily targets diarrhea by slowing down the movement of the intestines. By doing so, it allows your body more time to absorb water and electrolytes, resulting in less frequent and firmer stools.

Key features of loperamide:

Mechanism: An opioid receptor agonist that slows gut motility.
Primary Use: Effective for controlling acute, non-specific diarrhea and traveler's diarrhea.
Speed: Can start relieving symptoms within an hour.
Safety: Not recommended for children under 2 without a doctor's guidance. Caution is advised in cases of fever or bloody stools, as it can prolong the illness if caused by an infection.

Bismuth Subsalicylate (Pepto-Bismol, Kaopectate)

Bismuth subsalicylate is a multi-symptom reliever for a range of digestive issues, including diarrhea, upset stomach, heartburn, and nausea. Its multifaceted action includes decreasing fluid flow, reducing inflammation, and acting as a mild antibacterial agent.

Key features of bismuth subsalicylate:

Mechanism: Antisecretory and antimicrobial properties.
Primary Use: Broad relief for nausea, indigestion, and diarrhea.
Side Effects: Can cause a temporary and harmless darkening of the tongue and stool.
Safety: Should not be given to children or teenagers recovering from viral illnesses (like the flu or chickenpox) due to the risk of Reye's syndrome.

Supportive Treatments: Hydration and Diet

Regardless of the cause, staying hydrated is the most crucial step in managing upset stomach and diarrhea, as significant fluid and electrolyte loss can lead to dehydration.

Oral Rehydration Solutions (ORS)

ORS are specially formulated liquids containing balanced amounts of electrolytes (sodium, potassium) and glucose. They are more effective than plain water or sugary sports drinks for replacing lost fluids.

Tips for using ORS:

Take small, frequent sips, especially if vomiting is an issue.
Commercially available options include Pedialyte.
For adults, homemade solutions with water, salt, and sugar can be effective.

The BRAT Diet and Other Gentle Foods

Dietary modifications can significantly ease symptoms. Sticking to bland, easy-to-digest foods allows your digestive system to rest and recover.

Recommended foods:

BRAT diet: Bananas, rice, applesauce, and toast.
Lean protein: Plain chicken breast or fish.
Soup: Clear broths can help replace fluids and electrolytes.

Foods to avoid:

Greasy, fatty, or spicy foods.
Dairy products (milk, cheese), as temporary lactose intolerance can occur.
Caffeine and alcohol, which can worsen dehydration.
Sorbitol and other artificial sweeteners found in sugar-free products.

Medication Comparison: Loperamide vs. Bismuth Subsalicylate


Attribute	Loperamide (Imodium)	Bismuth Subsalicylate (Pepto-Bismol)
Primary Function	Slows intestinal motility to reduce diarrhea.	Decreases fluid flow, reduces inflammation, and acts as a mild antibacterial.
Main Use Case	Primarily for acute or chronic diarrhea.	Broad relief for upset stomach, diarrhea, nausea, and heartburn.
Considerations	Can prolong infection-related diarrhea; high doses carry heart risks.	Contains salicylates (aspirin-like), should be avoided in children/teens with viral illness.
Side Effects	Constipation, dizziness, fatigue.	Harmless darkening of tongue and stool.
Patient Profile	Adults seeking quick diarrhea relief; prescription for specific conditions like IBS-D.	Adults needing multi-symptom relief; general upset stomach.

When to See a Doctor

While many cases are manageable at home, certain symptoms warrant immediate medical attention. Consult a healthcare provider if you experience any of the following:

Diarrhea lasting more than two days in adults, or more than one day in a child.
Fever over 102°F.
Severe abdominal or rectal pain.
Signs of severe dehydration (excessive thirst, dry mouth, little to no urination).
Bloody, black, or mucus-filled stools.

Conclusion: Choosing the Right Treatment for You

There is no single best medicine for upset stomach and diarrhea. The most appropriate choice depends on your specific symptoms, their severity, and any underlying conditions. For isolated diarrhea, loperamide offers targeted relief. For a broader range of digestive discomfort, including nausea and indigestion, bismuth subsalicylate is a versatile option. However, these OTC treatments should always be used in conjunction with a proactive hydration strategy, such as using oral rehydration solutions, and a bland diet. For children, or if you experience severe or persistent symptoms, a doctor’s consultation is essential. Always read the package directions carefully and consult a pharmacist or doctor if you have questions about which medication is right for you, especially if you have other health conditions or are taking other medicines.

Frequently Asked Questions

Choose Pepto-Bismol if you have both diarrhea and other symptoms like an upset stomach, nausea, or heartburn. Choose Imodium if your primary symptom is diarrhea, as it is more focused on slowing intestinal movement.

For children under 12, it is best to consult a pediatrician before giving any OTC medication for diarrhea. Bismuth subsalicylate (Pepto-Bismol) is not recommended for this age group due to the risk of Reye's syndrome.

The BRAT (Bananas, Rice, Applesauce, Toast) diet is often recommended because these foods are bland and can help bind stools. While a useful short-term solution, it should not be followed for an extended period due to its limited nutritional value.

When experiencing an upset stomach, you should avoid greasy, fatty, or spicy foods, dairy products, caffeine, and alcohol, as they can irritate the digestive tract.

The most important treatment is staying hydrated. Use an oral rehydration solution (ORS), which contains a balanced mix of water, electrolytes, and sugars, to prevent dehydration.

Diarrhea can be a side effect of many medications, including antibiotics and some antacids containing magnesium. If you suspect your medication is the cause, consult your doctor.

Signs of dehydration include decreased urination, excessive thirst, dry mouth, dizziness, fatigue, and sunken eyes. If you experience these symptoms, it is crucial to rehydrate immediately and potentially seek medical care.