• Digestive Disorders

Loperamide vs. Bismuth for Diarrhea: What’s the Difference?

Published: October 21, 2025
Updated: October 21, 2025
4 mins

It’s not uncommon to eat something that makes your stomach feel funny. Diarrhea causes more frequent loose or watery bowel movements. You can easily treat most cases of diarrhea that last less than a week. Within one to two days, symptoms tend to subside on their own. Some people may also experience abdominal pain, fatigue, and nausea. 

Diarrhea is most commonly caused by consuming contaminated foods, having lactose intolerance, or gastrointestinal conditions like Crohn’s disease and irritable bowel syndrome.

Fortunately, most cases of upset stomach subside over time as your digestive system processes any triggers. You can find many options for OTC (over-the-counter) medications for adults with upset stomach, indigestion, and diarrhea. It’s normal to see changes in your stool, but diarrhea is a common condition that can be a more imposing health condition that can interrupt daily life.

Loperamide and bismuth subsalicylate are popular OTC medications for treating diarrhea. You may recognize them by their brand names, Imodium® (loperamide) and Pepto-Bismol® (bismuth subsalicylate).

What is Loperamide?

Loperamide is an antidiarrheal medication used to treat diarrhea lasting less than two weeks in children over the age of 2 and adults. You can take loperamide in capsule, tablet, or liquid form. Dosages range from 2 to 8 mg (milligram) doses. You can take loperamide on an as-needed basis.

It works by slowing the movement of muscles in the intestines. Taking loperamide helps the body absorb fluids more easily. Generally, health experts suggest taking the recommended dosage on the label each time you have a loose bowel movement.

Side effects of loperamide

When taking loperamide, you may experience the following side effects:

• Nausea

• Constipation

• Dry mouth

• Abdominal pain

• Dizziness

• Drowsiness

What is Bismuth Subsalicylate?

Pepto-Bismol (bismuth subsalicylate) is a medication used to treat diarrhea, upset stomach, and heartburn. Like loperamide, bismuth subsalicylate is available in capsule, tablet, or liquid form. Liquid Pepto-Bismol dosages range from 10 to 30 mL (milliliter) dosages. Health experts recommend taking the medication after having a loose or watery bowel movement.

Bismuth subsalicylate reduces intestinal inflammation, fluid in the bowels, and kills harmful microorganisms that may worsen diarrhea. Health experts recommend drinking lots of water while taking bismuth subsalicylate.

Side effects of bismuth subsalicylate

You may experience the following side effects while taking Pepto Bismol (bismuth subsalicylate):

• Ringing in the ear

• Nausea

• Dark urine

• Black stool

• Bitter taste in your mouth

Is Loperamide Better than Bismuth Subsalicylate?

Which medication works best for you depends on several factors, like other medications you’re taking, health conditions you have, and your lifestyle. Pepto-Bismol may be a better option if you’re also experiencing an upset stomach or heartburn.

Past studies have suggested that loperamide is slightly more effective than bismuth subsalicylate at reducing the frequency of bowel movements. However, new research is needed to confirm which medication is more effective.

Other Medication Options for Diarrhea

Health experts only recommend taking loperamide and bismuth subsalicylate for no longer than seven days. The following medications work for the treatment of chronic diarrhea:

• Clonidine

• Somatostatin

• Aloestron

• Antimicrobials

Foods to Avoid When You Have Diarrhea

Paying attention to what you eat can help you know how to prevent diarrhea in the future. When you have diarrhea, the following foods may further exacerbate symptoms:

• Fried foods

• Pizza

• Dairy products

• Caffeine

• Alcoholic beverages

For those with chronic diarrhea, a healthcare provider may recommend major changes to your diet. Food allergies and digestive conditions can lead to diarrhea. A healthcare provider may ask you to keep a journal of everything you eat and drink while having diarrhea to get a better idea of what could be causing your symptoms.

Who Should Not Take Loperamide or Bismuth Subsalicylate?

If you’re experiencing chronic diarrhea, a healthcare provider can prescribe you something stronger than OTC medications. You may also want to consult a healthcare provider before taking either medication if you are only on certain prescriptions.

For example, loperamide may negatively interact with the following medications:

• Itraconazole (Sporanox)

• HIV medications

• Ritonavir (Norvir)

Bismuth subsalicylate may worsen symptoms when taken at the same time as the following medications:

• Blood thinners

• Diabetic medication

• Arthritis medication

A healthcare provider may not recommend taking OTC antidiarrhetic medications if you have a history of kidney disease.

Tips for Managing Diarrhea at Home

Stay hydrated: Health experts recommend staying hydrated when you have diarrhea. Some people with diarrhea may experience dehydration due to a loss of fluid.

Keep your hands clean: When you have diarrhea, it’s important to keep your hands clean to avoid spreading any infections that may cause diarrhea. After using the restroom and before handling any food, wash your hands for at least 20 seconds.

Carefully prepare your food: Food poisoning is a common cause of diarrhea. Proper storage of foods, especially raw meat, can help prevent your chances of having diarrhea. Thoroughly cook meats at a safe temperature to reduce the risk of food contamination.

When to See a Healthcare Provider

OTC medications are not recommended for those with bloody stools or who have been experiencing diarrhea for longer than a week. Diarrhea that lasts for too long is often a sign of an infection. Prescription medications can help your body manage chronic diarrhea and retain hydration.

Where Can I Learn More About Digestive Health?

Typically, acute (short-term) diarrhea is easily treated with OTC medications. However, more severe cases require guidance from a licensed healthcare provider. With LifeMD, a qualified provider can help you with the next steps to finding relief.

Get started today with finding relief for diarrhea and other gastrointestinal concerns.