Medications to treat diarrhea in adults include over-the-counter remedies, such as loperamide and bismuth subsalicylate. People with an underlying health condition or infection may need prescription drugs like rifaximin.

Diarrhea is when stool contains too much water, causing runny stool. Diarrhea occurs when the small and large intestine cannot absorb ions, such as salt. As a result, the intestines are also unable to absorb water into the body, leading to watery stools.

Diarrhea can be either acute or chronic. Acute diarrhea typically refers to passing at least three loose stools a day for up to 14 days. A doctor may describe diarrhea lasting between 2 and 4 weeks as persistent and cases lasting longer than 4 weeks as chronic diarrhea. In most cases, the condition resolves within a few days.

There are three types of infection that can cause diarrhea:

Depending on the cause, different medications are available for diarrhea. Typically, treatment options involve regulating gastrointestinal movement and increasing fluid absorption in the intestines.

In this article, we will discuss medications that can help relieve diarrhea.

Medicine bottles on a production line.Share on Pinterest
Comezora/Getty Images

OTC medications are available for acute diarrhea. However, if symptoms persist, a person may require different treatment to target whatever is causing it. Common medications for diarrhea include loperamide and bismuth subsalicylate.


Loperamide, which people commonly refer to by its brand name, Imodium, is an anti-diarrheal agent that treats diarrhea by affecting the opiate receptors in the intestine. This drug works by slowing the contractions of the intestines and how quickly its contents pass through. By slowing the movement, it allows more time for water reabsorption.

Potential side effects of loperamide can include:

It is also worth noting that loperamide is not a controlled substance, and there is a risk of overdosage and severe adverse reactions. As such, the recommended usage for adults and those 13 years and older is an initial dose of 4 milligrams (mg) or 2 capsules, then 2 mg or 1 capsule after each loose stool. It is not advisable to exceed 16 mg or 8 capsules per day.

Bismuth subsalicylate

Bismuth subsalicylate, which people know by the brand names Kaopectate and Pepto-Bismol, is another OTC medication for treating diarrhea.

As the drug passes into the stomach, it divides into bismuth and salicylic acid as two separate compounds. The bismuth remains in the stomach, where it helps increase fluid absorption, reduce inflammation, and heal the stomach. The bismuth can do this due to its bactericidal and antimicrobial activity that can inhibit the pathogens causing diarrhea.

Bismuth subsalicylate may cause the following side effects:

As this drug contains salicylate, it is not advisable for people with allergies, such as aspirin, to use bismuth salicylate. Additionally, this drug may interact with other medications. As such, it is advisable to consult a doctor before using it if a person takes any drugs for:

Prescription medication is generally more specific to the cause of diarrhea. These types of medication can include the following:


Alosetron is a form of treatment for individuals with severe diarrhea-predominant irritable bowel syndrome (IBS-D). It blocks the receptors that cause pain, abdominal discomfort, and diarrhea. Side effects of alosetron can include constipation and ischemic colitis, which reduces blood flow to the large intestine.


Eluxadoline, available under the brand name Viberzi, is another treatment for IBS-D. This medication affects opioid receptors and manages symptoms by regulating gastrointestinal movement, secretion, and discomfort. It causes fewer side effects than alosetron, but more studies are necessary to determine its effectiveness compared with other medications.


Rifaximin, which has the brand name Xifaxan, is a form of treatment for both IBS-D and traveler’s diarrhea. It is an antibiotic, so it is important to make sure the person taking it has not contracted viral diarrhea. Rifaximin works by fighting gram-negative and gram-positive anaerobic and aerobic bacteria, so it can treat a range of cases.

Some people should avoid taking diarrhea medications. For example, OTC diarrhea medications can be dangerous for:

  • infants
  • toddlers
  • young children

Additionally, people should avoid OTC medication if there is blood in their stool, the person has a fever, or there are other signs of either bacterial or parasitic infection. If diarrhea persists for more than 2 days, it is advisable to consult a doctor.

Individuals should always make sure any medication they take does not contain an ingredient that may cause an allergic reaction. If they are unsure, they can check with a doctor or pharmacist. Additionally, someone who is pregnant should check with a healthcare professional before taking new medication.

Stay hydrated

Diarrhea causes a risk of dehydration and, in long-term cases, malnutrition. The first step of treatment is to try to replace the fluids and electrolytes that are leaving the body. People can use sports drinks that contain salts and sugars to help promote water absorption. If the body is still unable to absorb water, intravenous fluid replacement may be necessary.

Eat low fiber or bland foods

To make the stool less runny, a person may consider consuming low-fiber foods or following the BRAT diet. BRAT stands for bananas, rice, applesauce, and toast. The bland diet, which includes more foods but still minimizes fiber, spice, and high-consistency foods, may also be useful for people with diarrhea symptoms. However, as these diets may be low in nutritional value and calories, some health experts no longer recommend them.

Learn more here about what to eat and drink when experiencing diarrhea.

Washing hands regularly and thoroughly is important for preventing the spread of infectious diarrhea. If a person has acute diarrhea, they should stay home and avoid going to public places, such as school or work, until their symptoms resolve. Vaccination is available against rotavirus, a common infectious cause of diarrhea.

In areas where food and water are more likely to contain harmful pathogens, it is better to avoid tap water and drink water from bottles instead. Before buying bottled water, people should check the seal to ensure it is still intact. It may also be advisable to avoid raw vegetables and fruits and stick to well-cooked meals that have not been sitting on a buffet.

To prevent dehydration from diarrhea, people can use oral rehydration therapy or electrolyte drinks as soon as they notice symptoms.

Below are some commonly asked questions about diarrhea medicine.

What is the best remedy for diarrhea?

Home remedies for diarrhea include drinking plenty of water or sports drinks that contain electrolytes. Eating bland or low-fiber foods may also be useful for people with diarrhea symptoms.

What is the first drug choice for diarrhea?

For acute diarrhea, over-the-counter medications such as loperamide and bismuth subsalicylate tend to be the first drug choice.

In other instances, prescription medications such as alosetron, eluxadoline, and rifaximin may be recommended.

Diarrhea typically refers to when people pass watery stool at least three times a day. There are different possible causes of diarrhea, and the condition can be acute or chronic, depending on how long it persists. Without treatment, the condition can result in severe complications.

As such, it is advisable to use medications to help relieve symptoms of diarrhea. Both OTC and prescription options are available, which aim to slow the passage of contents through the intestines and increase the absorption of fluids. In many cases, diarrhea resolves within a few days. However, if symptoms persist for more than 2 days, it is advisable to contact a doctor.