Understanding OTC Diarrhea Medicines

The best OTC antidiarrheal for you depends on a few key factors

An antidiarrheal is a drug that is used to slow down or stop diarrhea (loose stools). Antidiarrheals are used for acute, non-life-threatening situations, such as viral gastroenteritis (stomach flu).

Over-the-counter (OTC) antidiarrheal medications are found in most supermarkets, drug stores, and pharmacies. While OTC antidiarrheals work to alleviate symptoms, they rarely treat the underlying cause (for example, a virus or inflammation).

A hand holding 2 white pills

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For most adults, diarrhea happens occasionally and goes away on its own. In these cases, the cause probably remains a mystery, and medical intervention usually isn't necessary.

For people who have chronic digestive diseases, such as inflammatory bowel disease (IBD), taking something OTC for diarrhea might seem like a good idea. However, many OTC antidiarrheals are recommended for limited use only and can interact with medications you are already taking. People with IBD should follow their healthcare provider's advice to manage symptoms.

This article explores different OTC medications that relieve diarrhea symptoms, how to use anti-diarrheal drugs, and when to see a healthcare provider about your illness,

Understanding Diarrhea

Diarrhea occurs when your intestines are unable to absorb water into the body. When stool contains too much water it causes loose bowel movements. You have diarrhea if you experience runny stools three or more times in one day.

Diarrhea is a common condition that can have a wide variety of causes. In many cases, diarrhea will go away after a few days without treatment, and the cause may never be known.

The most common causes of diarrhea include:

  • Bacteria from contaminated food or water
  • Viruses (e.g., flu, norovirus, or rotavirus)
  • Parasites
  • Medicines (e.g., antibiotics, cancer drugs, or magnesium-based antacids)
  • Food intolerances and sensitivities (e.g., lactose or gluten intolerance)
  • Diseases that affect the stomach, small intestine, or colon (e.g., Crohn's disease)
  • Problems with how the colon functions (e.g., IBS)

When to Seek Medical Care

Consult a healthcare provider if your diarrhea continues for more than a couple of days, you run a fever, experience severe pain, see blood or pus in your stool, or are unable to stay hydrated.

Dehydration can be a consequence of diarrhea. Possible symptoms include:

  • Thirst
  • Dry mouth and/or cracked lips
  • Wrinkled skin
  • Headache
  • Feeling dizzy or faint
  • Weakness or unusual fatigue
  • Muscle cramps/pain
  • Dark yellow urine or urinating less frequently than usual
  • Increased heart rate
  • Confusion

Focus on getting extra fluids (water, sports drinks) when sick. If you are having trouble keeping liquids down, try sucking on ice chips.

Using Antidiarrheal Drugs

As already mentioned, OTC antidiarrheal drugs are used to slow down or stop diarrhea. They are primarily used to treat fairly routine illnesses, like food poisoning. In most cases, medical treatment isn't necessary and the cause isn't diagnosed.

When taking OTC diarrhea medication:

  • Take only the amount recommended, for the length of time recommended on the medication you choose. Taking more, or using a product for longer, may be dangerous.
  • To avoid possible drug interactions, consult your healthcare provider before taking an OTC antidiarrheal if you are taking any prescription medications.
  • Do not take more than one OTC antidiarrheal at the same time (unless your healthcare provider specifically recommends it).

OTC antidiarrheals for IBS

A recent study found that, among people with IBS and dyspepsia, 28% of those who self-medicated used the wrong medication to treat their GI complaints.

For people who have chronic digestive diseases like irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD), taking something OTC for diarrhea might seem like a good idea. However, while OTC antidiarrheals may work to alleviate diarrhea symptoms, they don't treat the underlying causes of chronic bowel conditions. Your healthcare provider may recommend them, along with prescription medications and other treatment strategies, to control loose stools.

Antidiarrheals have been linked to a rare but severe condition known as toxic megacolon in people with ulcerative colitis and Crohn’s disease. These medicines should only be used by people with IBD under the direction and supervision of a gastroenterologist.

People who have had j-pouch surgery may be advised to use antidiarrheal medications, especially during recovery from the final surgery (takedown surgery) when the j-pouch is connected. Some people with j-pouches may use antidiarrheals on a long-term basis, while others might use them only as needed, such as when experiencing too many bowel movements a day.

Types of Antidiarrheal Drugs

Antidiarrheal medications are made from two main ingredients, loperamide and bismuth subsalicylate, which work in different ways.

There are prescription medications that are sometimes used for treating chronic diarrhea, and you can discuss with your doctor if those are appropriate for you.

Loperamide (Imodium)

Imodium, which can be purchased OTC, decreases the speed and number of intestinal contractions, slowing down diarrhea.

Side effects of loperamide can include abdominal pain, dry mouth, drowsiness, dizziness, constipation, nausea, and vomiting. People who have these side effects from loperamide may be unable to drive or do other activities that require concentration while taking it.

Also, if you have a history of heart rhythm problems, you should talk to your doctor before using loperamide.

If you haven't used loperamide before or aren't used to taking it regularly, avoid driving and operating heavy machinery until you know how it affects you.

Some people with J-pouches use this medication regularly and might get a prescription for it from a healthcare provider.

Bismuth Subsalicylate (Kaopectate and Pepto-Bismol)

Bismuth subsalicylate, found in Kaopectate and Pepto-Bismol, is better known for treating stomach upset. Still, it also works as an antidiarrheal and an anti-inflammatory, and it can inhibit the spread of some strains of bacteria that cause diarrhea.

Bismuth subsalicylate slows diarrhea by reducing the amount of water entering the bowels.

Side effects of Pepto-Bismol can include constipation, black stools, a black tongue, and (rarely) tinnitus. Overdoses of Pepto-Bismol can be dangerous, so only take the prescribed amount and don't double up doses.

Summary

Most cases of diarrhea resolve on their own within a short time. While antidiarrheal medications help to alleviate symptoms, they very rarely treat the cause. These medications contain two main ingredients: loperamide and bismuth subsalicylate. Follow packaging instructions concerning dosing and consult your healthcare provider before use if you are taking any prescription medicines.

If symptoms last for more than a few days, are accompanied by a fever, severe pain or blood or pus in your stool, or you are unable to stay hydrated, seek medical attention.

Frequently Asked Questions

  • Is antidiarrheal medicine available over the counter?

    Yes, various antidiarrheal medication options are available over the counter at pharmacies and many grocery stores. Pepto-Bismol and Kaopectate and their generic equivalents are two standard products. Alternatively, you can try Imodium, which slows intestinal contractions and reduces bouts of diarrhea.

  • Can Imodium cause constipation?

    Yes, constipation is one side effect of Imodium. Other potential side effects include dizziness, drowsiness, headache, nausea, and vomiting. Most people don't experience side effects from Imodium, but if you take other medications, talk to your healthcare provider first to see if there's a potential for medicine interactions.

  • How long does it take Imodium to wear off?

    A single dose of Imodium can last up to 14 to 38 hours. It takes about half an hour for the medicine to begin working.

10 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.
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Additional Reading
  • American Society of Health-System Pharmacists. "Bismuth subsalicylate." U.S. National Library of Medicine.

  • American Society of Health-System Pharmacists. "Loperamide." U.S. National Library of Medicine.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.