It takes 30 minutes to an hour for Pepto-Bismol (bismuth subsalicylate) to start working and help relieve diarrhea, upset stomach, and nausea.
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Sometimes referred to as "the pink stuff," Pepto-Bismol is an over-the-counter (OTC) medication that is safe and effective for short-term use. Side effects are generally mild and can include a black tongue, black stool, and constipation. More serious side effects can occur but are rare.
This article discusses Pepto-Bismol, how it works, and its potential side effects.
Uses for Pepto-Bismol
Pepto-Bismol is primarily used for the short-term treatment of the following digestive symptoms in adults and children age 12 and older:
- Diarrhea
- Nausea
- Stomach upset
- Indigestion
- Heartburn
- Excessive intestinal gas
- Excessive burping
- A feeling of fullness caused by eating too much
- Discomfort from drinking too much alcohol
Interestingly, researchers have found that when Pepto-Bismol is combined with antibiotics, it can be quite effective in treatingHelicobacter pylori—an infection that has been linked to peptic ulcers and gastritis.
How Pepto-Bismol Works
The scientific name for the active ingredient in Pepto-Bismol is bismuth subsalicylate.
Bismuth is a mineral that has antibacterial, antacid, and antidiarrheal effects.
Subsalicylate is a medication in the same class as aspirin.
The active ingredients of Pepto-Bismol are thought to have the following actions within the body:
- Increasing the amount of fluid that is absorbed in the intestines, therefore firming up stool
- Reducing inflammation
- Calming intestinal spasms
- Reducing the population of disease-causing bacteria and/or viruses
- Reducing excess levels of stomach acid
It can take half an hour for an hour for Pepto to "kick in." If it doesn't offer relief in that time, do not take another dose right away. Follow dosing instructions provided on the product packaging.
Pepto-Bismol Side Effects
Pepto-Bismol is considered quite safe for short-term use by adults and children age 12 or over. However, there are some side effects that you should be aware of, including:
- Blackening of the tongue
- Dark or black stool
- Constipation
These side effects are temporary and generally harmless.
Serious Side Effects
Serious side effects of Pepto-Bismol can occur, though they are rare:
- Bowel blockage: This can occur due to Pepto-Bismol-related constipation and is a particular concern in adults 65 and older.
- Reye's syndrome: The subsalicylate in Pepto-Bismol is in the aspirin family. Aspirin use in children and teenagers is associated with a risk of this potentially life-threatening illness. This risk is particularly high for those who have chickenpox, influenza (the flu), or any other type of viral infection.
Pepto Kids
Pepto Kids (calcium carbonate) is designed to treat heartburn and upset stomach in children. It does not contain bismuth subsalicylate, so it poses no risk of Reye's syndrome.
When to Call Your Healthcare Provider
Contact your healthcare provider immediately and stop taking Pepto-Bismol if you experience:
- Ringing in the ears
- Diarrhea that lasts for more than two days
- Severe vomiting
- High fever
- Any signs of an allergic reaction
If you think you have taken an overdose or are experiencing any severe symptoms, seek immediate attention by calling an ambulance.
Why Pepto Can Turn Stool Black
Before Taking Pepto-Bismol
Pepto-Bismol should be used for no more than two days . That makes it a poor choice for people who experience diarrhea, heartburn, or acid reflux that is chronic in nature.
Ask your healthcare provider about taking Pepto-Bismol before using it, as it may interact with other medications you are taking.
Drug Interactions
Pepto-Bismol can potentially interact with a wide range of medications. Let your healthcare provider know if you take any of the following before starting Pepto-Bismol:
- Arthritis or gout medications
- Blood thinners like warfarin
- Daily aspirin
- Diabetes medications
- Tetracycline antibiotics
Precautions and Contraindications
Pepto-Bismol should not be taken by anyone who:
- Is younger than 12 years of age (Pepto Kids is OK, however)
- Has the flu
- Has a fever and signs of blood in the stool
- Has chickenpox or has received the chickenpox vaccine within the past six weeks
- Is pregnant
- Is breastfeeding
- Is allergic to aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs), like Advil (ibuprofen) or Aleve (naproxen sodium)
Dosage
Pepto-Bismol is an oral medication that comes in liquid, tablet, or chewable form. Follow the directions and dosing recommendations on the product packaging carefully.
Do not take this medication for more than two days.
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Liquid
Use the provided dosing cup to take liquid Pepto-Bismol. (One dose equals one dosing cup filled to the top.)
If you've lost the dosing cup, look at the label to determine the strength of the formula, which dictates how much you should take:
- Original Strength: 30 milliliters (ml)
- Ultra-Strength: 15 ml
- Pepto Diarrhea Liquid: 10 ml
Dispense the dose using a medication syringe or cup that allows you to measure out a precise dose. Never use a kitchen spoon.
Do not exceed eight doses in a 24-hour period.
Chewable Tablets
Take two Pepto-Bismol chewables at a time. Do not exceed a total of 16 tablets in 24 hours.
Pepto Kids also comes in chewable tablet form. Dosing depends on a child's weight and age:
- Under 24 pounds/under age 2: Speak with a healthcare provider
- 24-47 pounds/ages 2 to 5: 1 tablet (maximum 3 tablets in 24 hours)
- 48-95 pounds/ages 6 to 11: 2 tablets (maximum 6 tablets in 24 hours)
If your child's weight and age do not correspond with one of the above, defer to the dosage that is appropriate for their weight.
Caplets
Pepto-Bismol caplets come in several different formulations. Take only the amount indicated on the label:
- Pepto-Bismol LiquiCaps: 2 caplets
- Pepto Diarrhea LiquiCaps: 2 caplets
- Pepto-Bismol Caplets: 2 caplets
- Pepto-Bismol Ultra Caplets: 1 caplet
Do not exceed eight doses in a 24-hour period.
Do You Need to Take Pepto-Bismol With Food?
You do not need to take Pepto-Bismol with food. However, be sure to drink plenty of water to replace fluid lost from diarrhea episodes.
Summary
Pepto-Bismol is an over-the-counter medication used to relieve digestive symptoms such as diarrhea and nausea. It works in a few different ways, including increasing the amount of fluid absorbed by your intestines and reducing inflammation.
Pepto-Bismol may cause side effects like a black tongue or constipation. These side effects are usually mild. Sometimes, however, it can cause more serious side effects like ringing in the ears or Reye's syndrome in children.
Don't take Pepto-Bismol for more than two days and avoid taking if you have health conditions like an aspirin allergy, if you're taking certain medications, or you are pregnant.
Frequently Asked Questions
How long does it take Pepto-Bismol to work?
Pepto-Bismol generally starts to work within 30 minutes to an hour. If you aren't feeling relief after an hour, you can take a second dose.
What are the side effects of Pepto-Bismol?
The most common side effect of Pepto-Bismol is a black tongue or black stools. Both are harmless. Pepto-Bismol contains a non-toxic metal called bismuth that, when mixed with sulfur (a naturally occurring mineral in the body), forms a black substance called bismuth sulfide.
Can Pepto-Bismol cause severe side effects?
On rare occasions, Pepto-Bismol has been known to cause potentially serious side effects. Call your healthcare provider if you experience severe vomiting, blood in the stool, vomit that resembles coffee grounds-like vomit, or ringing in the ears after taking Pepto-Bismol.
Learn MoreWhen to See a Healthcare Provider About Vomiting
Who should not take Pepto-Bismol?
Pepto-Bismol is contraindicated for use in people with aspirin allergy, gastric ulcer, hematochezia (bloody stools), hemophilia, flu-like symptoms (for children and teens only due to the risk of Reye syndrome).
Children under age 12 should not take regular Pepto-Bismol and children under 2 shouldn't be given Pepto Kids.
Is Pepto-Bismol safe during pregnancy?
Pepto-Bismol contains bismuth subsalicylate, a drug that is generally avoided during the third trimester as it increases the risk of uterine bleeding. There remains considerable debate about the actual risk, but it may be best to avoid Pepto-Bismol just to be safe.
9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
U.S. National Library of Medicine. Label:Pepto-Bismol—bismuth subsalicylate kit.
Graham DY, Lee SY. How to effectively use bismuth quadruple therapy: The good, the bad, and the ugly. Gastroenterol Clin North Am. 2015;44(3):537-63. doi:10.1016/j.gtc.2015.05.003
MedlinePlus. Bismuth subsalicylate.
Procter & Gamble. Pepto Bismol Original Liquid [package labeling].
Pepto Bismol. When & how to take Pepto Bismol?
Pepto Kids. The Procter & Gamble Manufacturing Company.
Pepto Bismol. FAQ.
KidsHealth. Reye Syndrome.
Servery J, Chang J. Over-the-counter medications in pregnancy. Am Fam Physician. 2014;90(8):548-55.
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By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.
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