bismuth subsalicylate (Pepto Bismol, Kaopectate)

What is bismuth subsalicylate-oral, and how does it work (mechanism of action)?

Bismuth subsalicylate (BSS) is a commonly used over the counter medicine used to treat:

Bismuth subsalicylate is also used to prevent traveler's diarrhea and to treat Helicobacter pylori (H. pylori) infection as part of a quadruple-drug therapy that also includes two antibiotics, and either a histamine-2 receptor antagonist or proton pump inhibitor.

Bismuth subsalicylate has various therapeutic benefits in the body including anti-bacterial, weak antacid, anti-inflammatory, and anti-secretory actions. After oral administration, bismuth subsalicylate is degraded in the stomach to produce salicylic acid. Salicylic acid inhibits the synthesis of prostaglandin, a chemical made in the body that plays an important role in contraction of smooth muscle and relaxation, dilation & constriction of blood vessels, blood pressure control, and modulation of inflammation.

The antidiarrheal benefits of bismuth subsalicylate may be due to the reduction in prostaglandin synthesis. Bismuth subsalicylate also prevents the attachment of bacteria to the walls of the intestine, inactivates enterotoxins (toxic chemicals made by bacteria), and has a direct inhibiting effect on bacteria.

Bismuth subsalicylate was first approved by the FDA in 1939.

What brand names are available for bismuth subsalicylate?

Bismatrol Maximum Strength, Pepto Bismol, Kaopectate, and many other brands

Is bismuth subsalicylate-oral available as a generic drug?


Do I need a prescription for bismuth subsalicylate?


What are the side effects of bismuth subsalicylate-oral?

Dark brown or black stools are common with use of bismuth subsalicylate. Tongue discoloration and constipation also may occur.

Other side effects associated with bismuth subsalicylate include:


Pancreatitis is inflammation of an organ in the abdomen called the pancreas. See Answer

What is the dosage for bismuth subsalicylate-oral?

Over-the-counter treatment of nonspecific diarrhea in adults and adolescents (= 12 years):

  • Chewable tablets, caplets, liquids containing 262 mg/15 ml: 524 mg by mouth every 30-60 minutes as needed. Not to exceed 8 doses in 24 hours.
  • Liquids containing 525 mg/15 ml: 1050 mg by mouth every hour as needed. Not to exceed 4 doses in 24 hours.
  • Over-the-counter treatment of upset stomach, heartburn, indigestion, nausea, and related symptoms in adults and adolescents (= 12 years):
  • Chewable tablets, caplets, liquids containing 262 mg/15 ml: 524 mg by mouth every 30-60 minutes as needed. Not to exceed 8 doses in 24 hours.
  • Liquids containing 525 mg/15 ml: 1050 mg by mouth every hour as needed. Not to exceed 4 doses in 24 hours.
  • For the prevention of traveler's diarrhea due to Escherichia coli (E. coli) and viral infections in adults and adolescents (≥ 12 years):
  • 524 mg by mouth four times daily, starting 1 day before departure and continuing for 2 days after returning. Generally, treatment duration should not exceed 3 weeks.
  • For the eradication of helicobacter pylori as part of quadruple-drug regimen in adults and adolescents (≥ 12 years):
  • 525 mg by mouth 4 times daily.

The safety and effectiveness of bismuth subsalicylate use in children <12 years has not been established.

Which drugs or supplements interact with bismuth subsalicylate-oral?

Combining bismuth subsalicylate with sulfinpyrazone (Anturane) or probenecid is not recommended because bismuth subsalicylate may suppress the therapeutic effects of both drugs.

Tetracycline and quinolone antibiotics may form insoluble complexes with bismuth subsalicylate. While bismuth subsalicylate should be avoided in patients taking these antibiotics if possible, separating administration by 2 hours may be sufficient to avoid this interaction.

Bismuth subsalicylate should be used cautiously in patients taking methotrexate (Trexall). Bismuth subsalicylate is broken down to salicylic acid which is known to increase blood levels of methotrexate. Patients especially at risk for this interaction include those on high-dose methotrexate therapy, elderly patients, and patients with reduced kidney function.

Bismuth subsalicylate is broken down to salicylic acid. Pediatric patients should not be given salicylates for 6 weeks after receiving the varicella-zoster virus live vaccine (Zostavax, Varivax) due to the risk of developing Reye's syndrome, a serious liver disease.


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Is bismuth subsalicylate-oral safe to take if I'm pregnant or breastfeeding?

Bismuth subsalicylate is known to cross the placenta following oral administration. Use of salicylates during pregnancy has been associated with adverse effects in the fetus. Therefore use of bismuth subsalicylate during pregnancy should be avoided. Bismuth subsalicylate is classified as FDA pregnancy risk category C (adverse effects in animals but inadequate human data).

Salicylates are excreted into human milk and can cause harm to the nursing infant. Bismuth subsalicylate is thought to be harmful to the nursing infant and should be avoided during breastfeeding.

What else should I know about bismuth subsalicylate-oral?

What preparations of bismuth subsalicylate-oral are available?

  • Chewable tablets: 262, 525 mg
  • Oral suspension: 262 mg/15 ml, maximum strength 525 mg/15 ml
  • Caplets: 262 mg

How should I keep bismuth subsalicylate-oral stored?

Bismuth subsalicylate products should be stored at room temperature, between 59 F to 86 F (15 C to 30 C).

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Bismuth subsalicylate (Pepto Bismol, Kaopectate, Bismatrol Maximum Strength, and many other brands) is an over-the-counter (OTC) drug used to prevent traveler's diarrhea, and to treat diarrhea, upset stomach, nausea, indigestion, heartburn, and H. pylori infection. Side effects, drug interactions, dosage, storage, pregnancy and breastfeeding safety should be reviewed prior to taking this medication.

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Medically reviewed by John P. Cunha, DO, FACOEP; Board Certified Emergency Medicine


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