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Reporting a Medication Error

Do You Need an Over-The-Counter (OTC) Medicine for Stomach Discomfort? Do Not Mix and Match!

Published December 8, 2023

An upset stomach, nausea, gas, and/or diarrhea (loose stool) can often be treated with over-the-counter (OTC) medicine. For example, Pepto Bismol (bismuth subsalicylate) is an OTC medicine familiar to most people. It can be used for nausea and diarrhea. However, there are other brand name (i.e., Kaopectate) and generic or store brand products that contain the same active ingredient, bismuth subsalicylate.

Figure 1. These products all contain the active ingredient bismuth subsalicylate. The two products on the right contain double the amount of bismuth subsalicylate.

Pepto Bismol and Kaopectate belong to a group of medicines called salicylates. In fact, the most commonly known salicylate is aspirin. So, taking too much can lead to side effects that are similar to aspirin, such as bleeding. However, bismuth subsalicylate breaks down into bismuth and salicylic acid once in the mouth and stomach. When the bismuth mixes with saliva and other digestive fluids, it can form a black substance that may cause your tongue and/or stools to look black. People who do not know about this side effect may worry because black stools are often a sign of bleeding. This color change is not harmful, but it may last a few days after the medicine is stopped.

Here's what you can do: Always read the Drug Facts label before purchasing medicine to treat symptoms such as upset stomach, nausea, gas, and/or diarrhea. Do not use two products that contain bismuth subsalicylate or aspirin at the same time. Always follow the dosing instructions on the Drug Facts label. Other important factors to consider when using products that contain bismuth salicylate include the following:

  • Do not use if you have an allergy to aspirin.
  • Do not take if you have an ulcer or bleeding disorder.
  • Do not give it to children who have a fever or are recovering from a viral infection, such as a cold, flu, or chickenpox because of the risk of Reye’s Syndrome. This is a serious and sometimes deadly condition in children that can harm the brain and liver.
  • If you take medicines for diabetes, gout, arthritis, or to prevent blood clots, check with your doctor or pharmacist before taking these medicines.

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