What Ingredients Are in Pepto Bismol? A Complete Pharmacological Breakdown

October 10, 2025 •

2 min read

Pepto Bismol has been a trusted over-the-counter remedy for over 100 years for common stomach ailments. But what ingredients are in Pepto Bismol that provide its multi-symptom relief? This article delves into the pharmacology of its active and inactive components.

Quick Summary

An in-depth look at the active and inactive ingredients in Pepto Bismol. This analysis covers the pharmacological action of bismuth subsalicylate and the function of each component for treating nausea, heartburn, indigestion, upset stomach, and diarrhea.

Key Points

Active Ingredient: The primary active component is bismuth subsalicylate, which has anti-inflammatory, antisecretory, and antimicrobial properties.
Inactive Ingredients: Inactive ingredients serve functions like preservation, coloring, flavoring, and maintaining consistency.
Mechanism of Action: The salicylate part reduces inflammation and fluid secretion, while bismuth has antimicrobial effects.
Common Side Effect: Temporary darkening of the tongue and stool can occur.
Reye's Syndrome Warning: Pepto Bismol must not be given to children or teenagers with flu-like symptoms or chickenpox due to the risk of Reye's syndrome.
Allergy Alert: Individuals allergic to salicylates, including aspirin, should not take this medication.
Drug Interactions: It can interact with blood thinners, and medications for diabetes, gout, and arthritis.

The Primary Active Ingredient: Bismuth Subsalicylate

The key active ingredient in Pepto Bismol is bismuth subsalicylate. In the original liquid formula, each 30 mL dose contains 525 mg of this compound. Bismuth subsalicylate works in several ways after being broken down into bismuth and salicylic acid in the gastrointestinal tract. The salicylate component helps reduce the flow of fluids and electrolytes into the bowel, which is beneficial for diarrhea. It does this by inhibiting the formation of prostaglandins, which are involved in inflammation and gut motility. The bismuth part has antimicrobial effects against bacteria and viruses that can cause stomach issues. Additionally, the salicylate has anti-inflammatory properties that can help calm an irritated intestine. Together, these actions allow Pepto Bismol to treat nausea, heartburn, indigestion, upset stomach, and diarrhea.

A Deep Dive into the Inactive Ingredients

Inactive ingredients are crucial for the product's form and taste. For a comprehensive list of inactive ingredients in the original liquid formula, refer to {Link: DailyMed https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=67006e82-870d-8d63-e053-2991aa0a02d1}. These ingredients serve various purposes such as preservation, coloring, flavoring, and maintaining the product's consistency.

Pharmacological Action and Common Side Effects

A common, non-harmful side effect is the temporary darkening of the tongue and stool. This is caused by the bismuth reacting with sulfur compounds in the body.

Comparison Table: Pepto Bismol vs. Alternatives


Medication	Active Ingredient	Primary Use	Mechanism of Action
Pepto Bismol	Bismuth Subsalicylate	Diarrhea, Heartburn, Nausea, Indigestion	Antisecretory, antimicrobial, and anti-inflammatory.
Imodium	Loperamide	Diarrhea	Slows down gut movement, allowing more water to be absorbed from the stool.
Tums	Calcium Carbonate	Heartburn, Indigestion	Neutralizes stomach acid directly.
Pepcid	Famotidine	Heartburn, Acid Reflux	An H2 antagonist that reduces the amount of acid produced by the stomach.

Safety, Side Effects, and Precautions

Precautions should be taken when using Pepto Bismol. Children and teenagers recovering from chickenpox or flu-like symptoms should not use it due to the risk of Reye's syndrome. Those with salicylate allergies (like aspirin) should avoid it. It should not be used if you have ulcers, bleeding problems, or bloody/black stools. Interactions can occur with certain medications; consult a healthcare provider if taking blood thinners or medications for diabetes, gout, or arthritis. Medical advice is recommended before use during pregnancy or breastfeeding.

Conclusion

Pepto Bismol is effective due to its active ingredient, bismuth subsalicylate, which offers multiple benefits. Inactive ingredients ensure the product's quality. Caution is needed due to its salicylate content, especially regarding Reye's syndrome and potential drug interactions. Always check the product label and consult a healthcare professional. An authoritative source for drug information is the National Library of Medicine's DailyMed site.

Frequently Asked Questions

The main active ingredient in Pepto Bismol is bismuth subsalicylate. It provides relief by acting as an anti-inflammatory, antimicrobial, and antisecretory agent.

This is a temporary and harmless side effect. It happens when the bismuth in the medicine mixes with the small amount of sulfur in your saliva and digestive tract, forming bismuth sulfide, which is black.

No. Pepto Bismol contains salicylates, which are in the same drug family as aspirin. You should not take it if you have a known allergy to aspirin or other salicylates.

Inactive ingredients serve various functions such as providing color, acting as thickeners, and functioning as preservatives. A detailed list of these ingredients can be found at {Link: DailyMed https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=67006e82-870d-8d63-e053-2991aa0a02d1}.

Pepto Bismol should not be given to children or teenagers 12 and under, especially if they have or are recovering from chickenpox or flu-like symptoms, due to the risk of Reye's syndrome, a rare but serious illness.

Pepto Bismol (bismuth subsalicylate) treats diarrhea, heartburn, indigestion, and nausea with anti-inflammatory and antimicrobial actions. Imodium (loperamide) is primarily for diarrhea and works by slowing down the movement of the gut.

The original liquid formula of Pepto Bismol is sweetened with sucralose, an artificial sweetener, and does not contain sugar. Different formulations may vary.