Diarrhea Every Day After Eating

If you suffer from diarrhea every day after eating, you may have postprandial diarrhea.

There are numerous causes of postprandial diarrhea, depending on whether it’s acute (lasts less than 14 days) or chronic (lasts more than 14 days). However, it’s not uncommon for postprandial diarrhea to occur without a specific cause.

If you experience postprandial diarrhea for more than three weeks — or if it occurs on three days in a row — you must seek medical attention for it.

Other scenarios where you must consult a doctor are discussed later in this article.

What are the causes of acute postprandial diarrhea (PD)?

Causes of acute PD include infectious conditions, food intolerances, toddler’s diarrhea, and magnesium overdose.

Acute PD comes on abruptly and may resolve on its own. Sometimes, medication might be needed to put a stop to diarrhea.

Infectious conditions of the gut

Viruses, bacteria, and parasites can all infect the gut and make it hypersensitive. This leads to acute diarrhea.

The most common type of parasite to infect the gut via food is the tapeworm (also called Taenia solium). Tapeworm reaches the gut via undercooked pork, and apart from diarrhea, can cause abdominal pain, loss of appetite, weight loss, nausea, and vomiting.

If your PD starts after eating pork, you may have Taeniasis, and PD can persist after other symptoms resolve.

Viruses and bacteria (like Salmonella and E. coli) also often reach the gut via contaminated food. Sometimes, the body reacts violently to bad food and you may experience immediate vomiting or diarrhea after you consume it.

Food intolerances

Food intolerance occurs when you lack an enzyme required to break down and digest a molecule in the diet.

Lactose intolerance is a common food intolerance and occurs when you’re missing lactase. Lactase is the enzyme needed to break down the milk sugar lactose.

People with lactose intolerance may experience PD after consuming dairy products. This is because undigested lactose makes its way to the large intestine, where it’s fermented by bacteria. Bacteria release gas in this process, which can lead to uncomfortable abdominal symptoms.

Fructose intolerance is another type of food intolerance. While it can occur due to a missing enzyme, fructose intolerance more commonly occurs because the body is hypersensitive to it (and not due to a missing enzyme).

Fructose is found in most fruits and honey, so if your diarrhea is triggered by these items, you may have fructose intolerance.

Toddler’s diarrhea

Toddler’s diarrhea occurs in young children who consume a lot of fruit juice. Fruit juice contains sugars like fructose, which are osmotic. This means they increase the water content of the gut and may lead to diarrhea.


Increased magnesium levels (hypermagnesemia) can lead to diarrhea. Hypermagnesemia can occur due to:

● Dysfunctional kidneys
● Burns
● Surgery
● Dietary supplementation of magnesium
● Use of laxatives and drugs like magnesium hydroxide

You should know that hypermagnesemia is an unlikely cause of your PD because it’s often accompanied by other symptoms as well. These can include lethargy, blurry vision, muscle weakness, and a number of cardiac problems.

What are the causes of chronic PD?

Causes of chronic PD include Irritable Bowel Syndrome (IBS), microscopic colitis, celiac disease, surgical causes, and bile acid malabsorption.

Unlike acute PD, chronic PD is unlikely to resolve on its own and you’ll have to seek treatment for it.

Irritable Bowel Syndrome (IBS)

IBS is a chronic gut condition characterized by abdominal pain. There are various types of IBS and patients with the IBS-Diarrhea subtype may experience chronic PD.

Lactose-intolerance is also common in IBS patients, which may be another cause of PD in these people.

Microscopic Colitis

Microscopic colitis leads to inflammation of the large intestine. Diarrhea can occur if the large intestine malfunctions. You may also experience cramping and gas if you have the condition, and symptoms can come and go.

Celiac disease

Celiac disease occurs when the body is hypersensitive to gluten. Gluten is a protein found in grains like wheat and barley, and in celiac disease patients, the immune system overreacts to gluten in the diet. This leads to abdominal symptoms.

The only treatment for celiac disease is a life-long gluten-free diet. If your diarrhea gets triggered after eating gluten-rich foods, it’s best to consult a doctor as long-lasting, untreated disease can lead to serious complications like small-bowel cancer.

Surgical causes

The two surgical causes of chronic PD include dumping syndrome and gallbladder removal.

Dumping syndrome is seen in patients who’ve had weight loss surgery. This leads to rapid emptying of the stomach into the small intestine, which can trigger diarrhea-causing reflexes.

Most patients who have gallbladder removal surgery experience diarrhea after it. In most cases, however, it resolves on its own. Sometimes, it can turn into long-term PD.

Bile acid malabsorption

Bile acids are produced by the liver to help absorb fats.

If they are not reabsorbed in the small intestine, bile acids can irritate the colon and lead to diarrhea.

What to do if you have diarrhea after eating?

First, determine if it’s long-term or acute. If your diarrhea has persisted for more than three weeks, you must see a doctor. You must also see a doctor if you have the following symptoms accompanying your diarrhea:

● Fever — greater than 38.8°C
● Severe abdominal pain while passing stool
● Black or gray stools
● Signs of severe dehydration like mental confusion, extreme thirst, dark urine, and muscle cramps

If your diarrhea is acute, taking over-the-counter antidiarrheal drugs and drinking plenty of fluids (especially those containing salt) may help to resolve it. Eating bland foods like rice, potatoes, and soups may also be helpful.

Learning to regulate stress and anxiety and eating smaller, more frequent meals can also help with diarrhea.

Finally, maintaining a food diary can help you identify trigger foods in case you have long-term diarrhea. This is where you write down everything you eat and how you feel after eating it for a month or two. You can then review this diary with a doctor to identify patterns and avoid the foods that lead to diarrhea.

Medically Reviewed by Onikepe Adegbola, MD PhD

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