Will Pepto make me stop having diarrhea? A detailed look at how it works

October 13, 2025 •

3 min read

According to the National Institutes of Health, bismuth subsalicylate is effective for treating diarrhea, especially traveler's diarrhea. The question of, 'Will Pepto make me stop having diarrhea?', can therefore be answered with a qualified 'yes' for many instances of mild to moderate diarrhea.

Quick Summary

Pepto-Bismol's active ingredient, bismuth subsalicylate, helps to relieve diarrhea by reducing inflammation, slowing fluid movement, and fighting certain bacteria. It is an effective short-term treatment for adults and children over 12, but has specific precautions and potential side effects.

Key Points

Active Ingredient: Pepto-Bismol's active ingredient is bismuth subsalicylate (BSS), which helps treat diarrhea.
Multiple Actions: BSS works by reducing inflammation, slowing fluid movement, and fighting certain bacteria in the gut.
Not for Children: Pepto-Bismol is not recommended for children under 12 due to the risk of Reye's syndrome.
Temporary Side Effects: A temporary and harmless darkening of the tongue and stool can occur when taking Pepto-Bismol.
Usage Duration: Treatment should not exceed two days without a doctor's consultation, and specific usage instructions must be followed.
Consult a Doctor: Seek medical advice if symptoms last more than two days, worsen, or if you have a fever, bloody stool, or hearing issues.

How Pepto-Bismol Works to Control Diarrhea

Pepto-Bismol, containing bismuth subsalicylate (BSS), addresses diarrhea through multiple actions. It works to alleviate symptoms and restore intestinal balance.

Mechanism of Action Explained

BSS has antimicrobial properties that target certain bacteria that can cause diarrhea. This can be particularly helpful in cases of bacterial infections like some forms of traveler's diarrhea. Additionally, BSS has an anti-secretory effect, reducing the flow of fluids and electrolytes into the intestine. By inhibiting inflammation-inducing prostaglandins, BSS aids in fluid reabsorption and firming stool. Pepto-Bismol also coats the stomach and intestinal lining, creating a protective layer that soothes irritation and provides relief from symptoms such as nausea and general upset stomach. The liquid formulation can offer this coating effect quickly.

Important Usage Instructions

Proper usage is essential for effective and safe use. Follow the instructions on the product packaging or as directed by a healthcare professional.

Shake liquid well before use.
Use the provided measuring cup for liquid doses.
Swallow caplets whole with water.
Limit use as directed and do not exceed the recommended duration.

Who Should Not Take Pepto-Bismol

While safe for many adults, Pepto-Bismol should be avoided in certain situations due to the salicylate component, similar to aspirin.

Children under 12 should not use Pepto-Bismol due to the risk of Reye's syndrome.
Individuals with allergies to aspirin or salicylates should avoid this medication.
Pepto-Bismol can interact with certain medications, including blood thinners, diabetes medications, and some arthritis or gout drugs. Consult a healthcare provider if you are taking other medications.
Do not use if you have a fever, a bleeding disorder, stomach ulcers, or blood or mucus in your stool.
Use is not recommended during pregnancy, especially in the last trimester.

Pepto-Bismol vs. Loperamide (Imodium): A Comparison

Pepto-Bismol is one of several over-the-counter options for diarrhea relief. Loperamide (Imodium A-D) is another common choice, but it works differently.


Feature	Pepto-Bismol (Bismuth Subsalicylate)	Loperamide (Imodium A-D)
Mechanism of Action	Coats stomach, reduces inflammation, has antimicrobial effects.	Slows down bowel movements, allowing for more water absorption.
Symptom Relief	Diarrhea, nausea, heartburn, indigestion, upset stomach.	Specifically targets diarrhea symptoms.
Speed of Relief	Typically works within 30-60 minutes, though can take up to 4 hours for severe symptoms.	Can work within 1-3 hours.
Best For	Mild, non-bloody diarrhea, travelers' diarrhea, or stomach upset with multiple symptoms.	Controlling acute or chronic diarrhea.
Potential Side Effects	Temporary darkening of tongue and stool, constipation, tinnitus.	Constipation, dizziness, drowsiness.
Age Restriction	Not for children under 12.	Can be used in children as young as 2 with a prescription.

When to See a Doctor

Most cases of diarrhea improve within a day or two with supportive care. However, medical attention is needed if you experience any of the following:

Symptoms persist or worsen after 2 days.
Development of a high fever.
Bloody or mucus-filled stools.
Ringing in the ears (tinnitus) or hearing loss.
Signs of dehydration, including reduced urination, extreme thirst, or dizziness.

Conclusion

Pepto-Bismol can be effective in treating mild to moderate diarrhea by coating the stomach, reducing inflammation, and fighting certain bacteria. It's a suitable option for adults and older children experiencing diarrhea and related symptoms. However, it is not recommended for children under 12 due to the risk of Reye's syndrome and should not be used for more than two days without medical advice. If symptoms are severe, persistent, or you have other health concerns, consult a healthcare professional for appropriate treatment guidance. The National Institutes of Health provides further information on its active ingredient.

Frequently Asked Questions

Pepto-Bismol typically starts providing relief from diarrhea within 30 to 60 minutes. For severe symptoms, it may take up to 4 hours for a noticeable improvement.

No, it is not. You should not use Pepto-Bismol for more than two days for diarrhea without consulting a healthcare professional. Prolonged use could indicate an underlying issue that requires a proper medical diagnosis.

The harmless and temporary blackening of the tongue and stool is caused by the bismuth in the medication reacting with trace amounts of sulfur in your saliva and digestive tract. This is not a cause for concern.

No, Pepto-Bismol is not for children under 12. The salicylate in the medication, which is similar to aspirin, can put them at risk for Reye's syndrome, a rare but serious illness.

Pepto-Bismol works by coating the stomach and fighting certain bacteria, while Imodium slows down the movement of your gut to allow for more water absorption. Pepto also treats other symptoms like nausea and indigestion, while Imodium is more specific to diarrhea.

If your diarrhea does not improve within two days, you should stop taking Pepto-Bismol and consult a doctor. Other reasons to see a doctor include a fever, bloody stool, or signs of dehydration.

The most common side effects are mild and include temporary darkening of the tongue and stool. Less common but potential side effects can include constipation, nausea, and ringing in the ears (tinnitus).