Imodium A-D vs. Pepto-Bismol for Diarrhea in Adults: Which Works Better?
Key takeaways:
Imodium A-D (loperamide) and Pepto-Bismol (bismuth subsalicylate) are two over-the-counter medications used to treat diarrhea in adults.
Imodium A-D mainly treats diarrhea. Pepto-Bismol (bismuth subsalicylate) can treat diarrhea and relieve other symptoms, like heartburn, indigestion, and nausea.
There’s some evidence that Imodium A-D works faster than Pepto-Bismol. But it can potentially interact with other medications you’re taking. Talk to your healthcare provider about the option that’s safest for you.
Table of contents
Let’s talk about diarrhea. It’s not the most glamorous topic to discuss, but it happens to the best of us. Diarrhea is a very common condition that can range in severity and causes. It generally occurs when there’s an imbalance in the amount of water that’s absorbed in the intestines. This can lead to frequent watery and loose stools.
Many cases of diarrhea are self-limiting, meaning that they’ll resolve on their own. But other cases may require medications for relief. Depending on the severity and cause of your diarrhea, over-the-counter (OTC) medications can be a convenient treatment option.
Two common OTC medications that treat diarrhea in adults are Imodium A-D (loperamide) and Pepto-Bismol (bismuth subsalicylate). But which works best for fast relief?
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What is Imodium A-D?
Imodium A-D is an OTC medication used to treat diarrhea in people ages 6 and older. This includes travelers’ diarrhea. Imodium A-D is available as an oral tablet, capsule, and liquid.
Loperamide is the active ingredient in Imodium A-D. It’s also available as a prescription product used to treat acute diarrhea, and chronic diarrhea in adults with inflammatory bowel disease (IBD). It can also be used to treat acute diarrhea in children ages 2 and older.
How does Imodium A-D work for diarrhea?
Imodium A-D works by slowing down the movement of fluids through your intestines. This allows your body to absorb water and electrolytes more efficiently from your gut. It also works on the muscles in the intestinal tract to help slow down bowel movements.
What is Pepto-Bismol?
Pepto-Bismol is an OTC medication used to treat diarrhea in people ages 12 and older. Unlike Imodium A-D, it’s also used to relieve other symptoms, including heartburn, indigestion, and nausea.
Pepto-Bismol is available as a regular or chewable oral tablet, capsule, and liquid. Bismuth subsalicylate, the active ingredient in Pepto-Bismol, is also available under the brand name Kaopectate.
How does Pepto-Bismol work for diarrhea?
Pepto-Bismol works in a few ways to treat diarrhea and relieve upset stomach. That’s because it becomes two different compounds inside your body: bismuth and salicylic acid.
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Bismuth helps your body absorb more water from your gut. This can result in less frequent and less watery stools. Additionally, it prevents certain bacteria from growing and attaching to the stomach lining. Salicylic acid helps lessen inflammation in your gut.
How are Imodium A-D and Pepto-Bismol dosed and given?
Imodium A-D and Pepto-Bismol are available in several different dosage forms. So, it’s best to check your specific product’s directions before use. Below are general dosing instructions.
Imodium A-D: Each Imodium A-D tablet or capsule contains 2 mg of loperamide. The recommended Imodium A-D dosage depends on your age.
For adults, you’ll take 2 pills (4 mg) after the first loose stool. After that, you’ll take another pill (2 mg) after each loose stool. But you shouldn’t take more than 4 pills (8 mg) in 24 hours.
Pepto-Bismol: The recommended Pepto-Bismol dosage for adults is 2 pills every 30 minutes as needed for diarrhea. You shouldn’t take more than 8 doses (16 pills) within 24 hours.
You shouldn’t use Imodium A-D or Pepto-Bismol longer than 2 days. Contact your healthcare provider if you’re still experiencing diarrhea.
How effective are Imodium A-D and Pepto-Bismol for treating diarrhea?
If you’re experiencing diarrhea, you’re likely looking for fast relief. But when comparing Imodium A-D and Pepto-Bismol, does one work better than the other?
One study published in 1990 suggests that loperamide (Imodium A-D) works better than bismuth subsalicylate (Pepto-Bismol) for treating acute diarrhea. Loperamide was able to provide faster relief compared to bismuth subsalicylate. However, there hasn’t been much research directly comparing them since.
So, you may want to consider your specific symptoms when making your decision. For example, Pepto-Bismol may be helpful if you also have an upset stomach.
And if you have other health conditions, or if you’re taking other medications, you’ll want to speak with your healthcare provider first. They can help you find the safest option for you.
What are the known side effects of Imodium A-D and Pepto-Bismol?
OTC medications are generally safe when taken as instructed. But they can still cause side effects. Below is a list of common Imodium A-D side effects and Pepto-Bismol side effects.
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Imodium A-D |
Pepto-Bismol |
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Keep in mind: These medications should only be used short term (no longer than 2 days). If these side effects continue after you’ve stopped treatment, let your healthcare provider know.
What are the serious side effects of Imodium A-D and Pepto-Bismol?
Although rare, serious side effects can happen with Imodium A-D and Pepto-Bismol. This is especially the case if you take more than the recommended amount.
Serious Imodium A-D side effects can include:
Swelling and inflammation of the colon
Life-threatening allergic skin reactions (like Stevens-Johnson syndrome)
Irregular heart rhythm (with higher-than-recommended doses)
Serious Pepto-Bismol side effects can include:
Reye’s syndrome (usually in children under 18 years old)
Allergic reactions if you’re allergic to aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs)
Salicylate toxicity (Pepto-Bismol overdose)
The information provided above may not include all potential side effects of Imodium A-D or Pepto-Bismol. Talk to your healthcare provider or pharmacist if you have any questions about what to expect when taking these medications.
What interactions do Imodium A-D and Pepto-Bismol have?
Imodium A-D goes through a specific pathway in your liver when it’s broken down (metabolized) by your body. And it can interact with other medications going through the same pathway. Examples of these medications include itraconazole (Sporanox), gemfibrozil (Lopid), and ritonavir (Norvir; also part of Paxlovid and some combination HIV medications).
The salicylic acid component in Pepto-Bismol is similar to aspirin. So, it could potentially interact with blood thinners, like warfarin (Coumadin, Jantoven), and raise the risk of bleeding. Because of this, it should also be avoided if you have a bleeding disorder.
If you’re taking other medications, it’s best to check with your pharmacist before starting Imodium A-D or Pepto-Bismol. They can review your medication list and recommend the safest option for you.
When should I see a healthcare provider for diarrhea?
OTC anti-diarrheal medications don’t require a prescription and are readily available at pharmacies, grocery stores, and even gas stations. But should you be reaching for one every time you have diarrhea? And when should you contact your healthcare provider?
You can typically treat acute diarrhea with OTC medications. Imodium A-D and Pepto-Bismol are two options to consider. But if your diarrhea lasts longer than 2 days, you should contact your healthcare provider.
Keep in mind: Not all types of diarrhea can or should be treated with OTC medications. If you have one of the following, you should talk to your healthcare provider first:
Gastrointestinal ulcers
Diarrhea with a fever
Diarrhea caused by bacteria or parasites
Symptoms of dehydration
Severe stomach or rectal pain
They can determine the cause of your diarrhea and recommend an appropriate treatment plan for you.
The bottom line
Imodium A-D and Pepto-Bismol are effective and convenient treatment options for diarrhea in adults. They can help to lower the frequency of watery and loose stools. And Pepto-Bismol can provide relief for an upset stomach, too.
However, they’re not meant to treat all types of diarrhea. Some kinds of diarrhea are caused by underlying health conditions or infections that may require prescription medications. If you’re unsure of how to treat your diarrhea, talk to your healthcare provider. They can help determine the cause of the diarrhea and find the most appropriate treatment option for you.
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References
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DuPont, H. L., et al. (1990). Comparative efficacy of loperamide hydrochloride and bismuth subsalicylate in the management of acute diarrhea. The American Journal of Medicine.
JC World Bell Wholesale. (2021). Pepto-Bismol chewable tablet [package insert].
Johnson & Johnson. (2021). Imodium A-D [package insert].
Johnson & Johnson. (2022). Imodium A-D capsule [package insert].
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Kramer Laboratories. (2021). Kaopectate [package insert].
National Institute of Neurological Disorders and Stroke. (2022). Reye’s syndrome.
Nemeth, V., et al. (2021). Diarrhea. StatPearls.
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Proctor and Gamble. (2021). Pepto-Bismol capsule [package insert].
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