Abdominal cramping and diarrhea soon after eating are some of the main symptoms of irritable bowel syndrome (IBS). Possible causes include exaggerated contractions in the colon, an imbalance of gut bacteria, and food intolerances.

IBS is a chronic condition that may resolve for some time and then recur unexpectedly.

It is the most common gastrointestinal (GI) condition in the world and affects 10–15% of people in the United States.

IBS is one potential cause of diarrhea after eating. Other causes include gastrointestinal disorders and food allergies.

This article looks at whether IBS can cause diarrhea after eating, other potential causes of diarrhea, whether certain foods can trigger diarrhea after eating, and how to treat and prevent it.

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IBS can cause diarrhea after eating. Researchers do not know how IBS causes diarrhea, but multiple factors may lead to loose, watery stool in people with the condition.

IBS may cause diarrhea after eating as a result of exaggerated contractions in the intestine.

When someone eats, food moves through the GI tract, from the mouth to the anus, in a process called peristalsis. The layer of muscle in the GI tract contracts behind the food, squeezing it forward, while the muscle ahead of the food relaxes to allow it to pass. This wave-like motion passes food from the start to the finish of the digestive process.

In someone with IBS, the muscles may contract rapidly, which can cause cramping and fast stool movement. As the stool moves along the GI tract more quickly than usual, the intestine cannot absorb water from the stool. This results in watery, loose diarrhea.

Some researchers believe that some people with IBS may have an imbalance in bacteria communities in the gut, which may also contribute to IBS symptoms such as diarrhea.

Researchers also believe that people with IBS may be more prone to certain food allergies and intolerances that may lead to diarrhea after eating, although more research is necessary.

Read about 10 signs and symptoms of IBS.

Diarrhea after eating may be acute, lasting 1–2 days, or chronic, lasting at least 4 weeks.

Causes of acute diarrhea after eating include:

Causes of chronic diarrhea after eating include:

The following types of foods may trigger diarrhea after eating in some people:

  • fried or greasy foods, which can pass through the body quickly
  • spicy foods, since chili peppers contain the chemical capsaicin, which can irritate the stomach lining
  • foods that contain lactose, which some people’s digestive systems cannot easily process
  • foods that contain fructose, which some people’s bodies do not tolerate well
  • foods that contain sugar alcohols, including artificial sweeteners such as xylitol and mannitol

Some foods, such as the following, can cause diarrhea in people who are allergic to them:

Learn more about foods to avoid with IBS.

Treatment for diarrhea after eating will depend on the underlying causes.

For someone with acute diarrhea, treatment may involve:

  • resting
  • drinking plenty of fluids to treat or prevent dehydration
  • eating soft, bland food until symptoms improve

Sports drinks or other drinks that contain sugar and salt but no caffeine or alcohol can help replace electrolytes. A person can also get oral rehydration fluids over the counter (OTC).

OTC medication may help improve symptoms and reduce the risk of dehydration.

Medications that may be beneficial include:

In people who have diarrhea after eating due to an autoimmune condition or another condition that affects digestive function, such as IBS, a doctor may prescribe medications such as:

Learn about coping with IBS.

A person should avoid foods that can trigger diarrhea after eating, such as those containing lactose, gluten, or fructose.

To prevent diarrhea from bacterial or viral causes, a person can:

  • Practice good hand hygiene: Washing hands often and thoroughly with soap and water, especially after using the bathroom and before and after preparing food, can reduce the risk of diarrheal disease by 48%.
  • Store and prepare food safely: Washing hands, preparation surfaces, and utensils; avoiding cross contamination of foods; and storing and cooking food at the right temperatures can help prevent food poisoning that may cause diarrhea.

If a person experiences diarrhea after eating due to IBS, they may be able to help prevent it by taking medication as their doctor prescribes it and avoiding foods that trigger symptoms.

A person should contact a doctor if they have:

A person should also contact a doctor if a child has diarrhea for longer than 24 hours.

Typically, diarrhea after eating passes within a few days, and a person can treat the symptoms by staying hydrated, resting, and eating bland foods until they feel better. OTC medications can help relieve symptoms and reduce the risk of dehydration.

If diarrhea after eating is chronic and results from IBS, a person can treat it with medication, such as antispasmodics and antidiarrheal medications. They can also avoid foods that may trigger diarrhea. IBS has no cure, but treatments can help people manage the symptoms.

IBS may lead to diarrhea after eating due to various causes, including exaggerated convulsions in the muscles of the GI tract.

There are many other potential causes of diarrhea after eating, such as food allergies and intolerances, food poisoning, and viral and parasitic infections.

Medications and dietary changes can help treat IBS symptoms such as diarrhea. A person can also help prevent diarrhea by avoiding trigger foods and practicing good food and hand hygiene.