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Diarrhea is when someone has loose, watery stools or bowel movements. When this occurs after eating, it is known as postprandial diarrhea. Postprandial diarrhea or PD can happen quite unexpectedly. It can also cause discomfort or pain until a bowel movement occurs.

PD is relatively common, but it may be difficult to figure out what is causing it and how to treat it. The reason for this is that PD can be a sign of a medical condition, or it can just happen with no specific cause.

Diarrhea is either acute or chronic, depending on how long the symptoms last. Acute diarrhea lasts for only a couple of days or weeks. Chronic diarrhea, on the other hand, can last for several weeks or months.

In this article, we take a look at the causes of both acute and chronic PD, along with what can be done to treat and prevent them.

There are many different causes of PD or diarrhea after eating, depending on whether it is acute or chronic.

Acute PD

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Acute PD will usually resolve by itself, or with some medication. Chronic PD will require medical attention.

Acute diarrhea usually lasts for fewer than 14 days. It is either treated with medicine or left to run its course. It can be caused by:


A viral infection, such as stomach flu, is the most common cause of acute diarrhea.

Food poisoning

Food or water that is contaminated by bacteria or other germs can cause diarrhea.

Eggs, poultry, soft cheeses, or raw foods are the most common culprits of this type of infection and diarrhea.

Lactose intolerance

Some people have an allergy to milk or are not able to digest lactose, which is the sugar in milk. This means that if they drink or eat milk, it can cause diarrhea, cramping, and gas.


Some parasites, most commonly found in food, can cause acute diarrhea. The symptoms tend to last until the parasite is identified and removed.

These types of parasites are not common in developed countries and are usually contracted while traveling.

Toddler’s diarrhea

Acute diarrhea is common in young children who drink a lot of sugary drinks, such as fruit juice. The high amount of sugar causes water to enter the intestines, making the stool more watery.


Some antibiotics can cause a stomach upset and acute diarrhea. The symptoms tend to resolve once the antibiotics are stopped.

Chronic PD

Chronic diarrhea is diarrhea that lasts for at least 4 weeks, with a minimum of three loose or watery bowel movements each day. Potential causes of chronic diarrhea may include:

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a disorder of the large intestine, causing bloating, cramping, and either constipation (IBS-C) or diarrhea (IBS-D).

IBS is a relatively common condition. Usually, it can be controlled with dietary changes, medication, and stress management strategies.

Inflammatory bowel disease

Inflammatory bowel disease (IBD) is an autoimmune disease, where the immune system causes inflammation and irritability in the intestines.

Crohn’s disease and ulcerative colitis are two examples of IBD. Both cause persistent diarrhea, cramping, weight loss, and tiredness.

Endocrine disorders

Some hormonal disorders, such as hyperthyroidism and diabetes, can cause chronic diarrhea, especially if there is nerve damage to the intestinal tract.

Celiac disease

Celiac disease is an autoimmune disorder that prevents people consuming gluten, the protein found in wheat and wheat products.

People with this condition have diarrhea whenever they eat food that contains wheat, barley, or rye.

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Soup broth and over the counter medication may help to treat diarrhea.

In most cases of acute diarrhea, the symptoms go away over time and can be managed at home.

Diarrhea can lead to dehydration if the lost fluids are not replaced. People with mild to moderate diarrhea can use the following to replace lost fluids:

  • electrolyte-replacement solutions, such as Gatorade or Pedialyte
  • watered-down apple juice
  • ginger ale
  • soup broth

It is important to use fluids that contain sugar and salt, to help replace lost electrolytes.

Someone with acute diarrhea should eat bland foods until their stomach is starting to feel better. Bananas, rice, soup, and crackers are particularly easy to digest and can help to harden stool.

As long as there is no fever or blood in the stools, medications can be used to reduce the frequency of loose stools. These will not cure the cause of diarrhea but can make someone feel better and cut down the fluid loss.

Medications are available including:

  • loperamide (Imodium)
  • diphenoxylate-atropine (Lomotil)
  • bismuth subsalicylate (Pepto-Bismol, or Kaopectate)

Hand-washing and other hygiene measures are crucial to prevent the spread of diarrhea if it has been caused by an infection. This is because very young and very old people are extremely prone to diarrhea and dehydration.

Frequent hand-washing with soap and water or an alcohol-based hand rub should be performed:

  • after changing a diaper
  • before and after preparing food or eating
  • after going to the bathroom
  • after touching any infectious material

People with diarrhea that does not improve with home measures or within 48 hours should see their doctor.

Someone with diarrhea in addition to any of the following symptoms should be seen promptly:

  • signs of dehydration, such as dry mouth, cramps, thirst, dark-colored urine, dizziness, not urinating, or confusion
  • signs of bleeding, such as bloody or black diarrhea, or stools that contain blood or mucus
  • a high temperature
  • severe stomach pain

Any of these symptoms may mean going to the emergency department, especially if there are signs of acute bleeding after the doctor’s office is closed.

A doctor will take a thorough history, do a physical exam, and may order additional diagnostic tests. Once the cause of the diarrhea is found, the appropriate treatment can begin.

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Drinking plenty of fluids and resting may help the diarrhea to pass quicker, and may ease the symptoms.

Treatment of diarrhea, whether it is acute or chronic, depends on its cause.

If an infection is to blame, medication may help. Sometimes rest, fluids, and time are all that is needed.

If diarrhea is caused by a specific food or substance, such as lactose or gluten, it is important to avoid those triggers in the future.

Chronic diarrhea caused by IBD or IBS may require the use of medication to control the immune system or inflammatory reaction.

Not all kinds of diarrhea are preventable. Hand hygiene and avoiding offending foods can go a long way toward preventing some causes of diarrhea.

Two forms of diarrhea can be prevented.

Rotavirus is a virus that causes diarrhea in young children. Most babies are vaccinated against the virus during infancy.

Only eating well-cooked food or drinking purified water while traveling can prevent traveler’s diarrhea, which results from exposure to contaminated water or foods.

In most cases, acute diarrhea is quickly cleared up once the cause is identified and treated.

While chronic diarrhea may have a more distinct medical cause, like IBD, the outlook is still good.

With some lifestyle changes and medication, if necessary, chronic diarrhea can be controlled and treated.

Some of the home remedies listed in this article are available for purchase online.