Diarrhea After Eating: Causes and Treatment

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Eating and pooping. They go together naturally, but it shouldn’t happen right after eating. This type of condition can have a real impact on your social life.

Not being able to go out for lunch with your friends or skipping a dinner date because you’re scared of the consequences shouldn’t be a regular occurrence. 

It’s known as postprandial diarrhea. It’s actually more common than you might think and there are some treatments to try if you’re living with this condition. 

But what causes postprandial diarrhea in the first place? What can you do about it? 

Today – we’ll find out. 


Postprandial diarrhea is the sudden urge to have a bowel movement right after eating and usually is a loose stool.

People that live with postprandial diarrhea usually feel pains in their stomach and bowels which is typically resolved after expelling stool. 

Postprandial diarrhea is most commonly a symptom of another condition, like irritable bowel syndrome with diarrhea.

This is not always the case though. Sometimes, it can happen for no obvious reason whatsoever. There are two main versions: chronic and acute.

One is long term and the other is infrequent or short term. 

Causes Of Acute Postprandial Diarrhea

There are many potential causes. It’s important to know the different causes for acute and chronic postprandial diarrhea. We’ll start with the potential causes for acute cases. Some of these include: 

1. Food Poisoning 

The human body has evolved and developed to understand what is good and bad for us.

If you’ve ever eaten some bad seafood, you might have had to rush to the nearest bathroom right after eating it.

Your body understands the pathogenic (problematic) bacteria that contaminated your food is causing an uproar inside your bowels and needs to get out as soon as it can – hence vomiting, diarrhea or both! 

2. A Viral Infection 

An example of a viral infection is the commonly known “stomach bug”.  Infections like Norovirus and Rotavirus can cause acute postprandial diarrhea.  Anything you’re eating might be coming right back out – but don’t worry, it’ll usually pass within a few days. 

3. Malabsorption Of Sugar 

This is when the body has an inability to absorb the sugars of certain foods like fructose. When it can’t absorb them and the sugar gets into the intestines – you’ll feel the urge to poop right away and you may have accompanying bloating and gas. 

4. Lactose Intolerance 

Similar to the last point, this is when your body cannot process the sugar known as lactose which is normally found in milk, yogurt and cheese. Some lactose intolerant people will get postprandial diarrhea after eating one of these products. Other lactose intolerant people may also experience bloating, gas or abdominal pain. Elimination of dairy can help reduce this type of postprandial diarrhea.

5. Children and Toddler Diarrhea 

If children consume a lot of sugar, for example in juice, they may end up exhibiting symptoms of postprandial diarrhea with watery stools. This is due to the large sugar content attracting water to the bowels. The same thing can happen in adults.

6. Overdose Of Magnesium 

Too much magnesium can lead to diarrhea. It’s a difficult mineral to get too much of through your diet, but it’s possible if you’re taking magnesium supplements or certain medications. 

7. Parasites

Places that do not practice good hygiene in their kitchens may have foodborne parasites – and if you eat their food, it’s possible for that parasite to get inside you!  A well known parasite is the tapeworm and it can cause postprandial diarrhea!  Sushi is a common source of parasitic infections.  Traveling to certain countries can also increase the risk of getting a parasitic infection.

Causes Of Chronic Postprandial Diarrhea 

Now, we’ll examine potential causes for chronic postprandial diarrhea. They might include: 

Irritable Bowel Syndrome (IBS) 

We mentioned this earlier, but IBS can have a variety of symptoms – one of which is diarrhea and often, people experience this immediately after eating. 

Surgery Complications 

Many people that have had surgeries like gallbladder removal, weight loss surgery (gastric bypass), and more can experience symptoms of postprandial diarrhea which can last weeks and even months. 

Microscopic Colitis 

This can cause an inflamed large intestine and one result is diarrhea. Unfortunately, the only way to diagnose this condition is through a colonoscopy with biopsies.  The colon lining will look normal to your doctor, but under the microscope, there is evidence of inflammation in the intestinal wall.

Celiac Disease 

This is a condition of the autoimmune system and may harm your intestines after consuming gluten which is found in wheat, barley and rye.  Eliminating gluten from the diet treats this condition and  can reduce symptoms like bloating and diarrhea.

The Malabsorption Of Bile Acid 

Often caused by a gallbladder problem, this is when the bile acid produced to digest foods isn’t being absorbed again in the end of the small intestine, which can affect the speed at which stool travels through the colon and lead to liquid diarrhea. 

Prevention Is Important 

If your postprandial diarrhea is not caused by any pre-existing condition, there are some basic things you can try to prevent it.

Sometimes, you cannot prevent it, and you’ll have to deal with it until it passes. Remember, your body knows best! 

Keep A Healthy Lifestyle 

With many health related matters, it’s important to stay fit and healthy. Studies have shown that keeping to a healthy diet with regular exercise can support a stronger immune system.

If your immune system is strong, your body’s response to pathogens like viruses, bacteria and parasites will be better, and you’re less likely to experience terrible symptoms (including diarrhea). 

Choosing the right foods is important too. If you’ve noticed certain foods send you directly to the bathroom, there could be a variety of reasons for this.

You might have an allergy or intolerance to that specific food, you might be intolerant to gluten or lactose and in some cases, it can be a psychological response. 

You’d be wise to keep a health diary. You can either do this physically or there are apps available to help. Keep a record of your daily food and drink intake and what exercise you’ve done that day. You can also keep track of when you have diarrhea to help determine if it occurs after all meals or just with certain foods.

Practice Good Hygiene 

Remember what we said about parasites? Keeping yourself and your surroundings clean and tidy is one of the most important ways to prevent foreign invaders to the body, which can lead to sickness and diarrhea.

Keeping designated areas in your kitchen for washing, raw and cooked foods is one way to help – if you cannot do this, it’s crucial to clean every item and area thoroughly.

Cleaning as you go is a good idea because it’s easy to forget things (like using the same knife you’ve just cut raw chicken with)! 

Always remember to wash your hands frequently. 

Chill Out 

Stress, anxiety and other psychological factors can affect you and your bowel habits. Your mind has incredible power over your body.

It’s important to dedicate time for yourself everyday, which can be easier said than done if you have a large family or a stressful job! 

Ask others to pitch in to help if you need to “check out” for a few minutes. 

If you’re living with more serious mental health complications, it’s important to speak with your doctor who might be able to prescribe some helpful medications.  Treating your mental health conditions can help improve any associated GI condition you might have.  

Change The Meals 

You might be used to 3 meals a day of a specific size but if you’re experiencing postprandial diarrhea, it’s not helping you.

Give your guts an easier job and split these meals out – instead of 3 large meals, you could have 6 smaller meals. 

Treatments For Postprandial Diarrhea

There is no “one size fits all” treatment because of its subjectivity and complexity. If you have an underlying condition like Crohn’s, ulcerative colitis, Celiac disease or IBS, optimizing your treatment regimen is probably the best way to reduce postprandial diarrhea.

The prevention methods listed above are good ways to start but it’s imperative that you speak with your doctor for specific treatments tailored to your needs. 

Should I Seek Medical Advice?

Seeking medical advice is always the best idea for anything health related, even when it comes to deciding what diet to consume or what exercise to do.

As we’ve seen, it’s not easy to sort out the cause of postprandial diarrhea (there are so many!), and it’s certainly not easy to treat without a proper assessment by a trained professional. 

However, you need to seek immediate medical advice if you’re experiencing any of the following: 

  • Diarrhea that is happening every day for over 7 days or wakes you up from sleep
  • Bowel movements that are extremely painful
  • Fever of over 102 degrees Fahrenheit 
  • Blood in your stool – this can be bright red, maroon or even black
  • Signs of dehydration (dark urine, confusion, extreme thirst, muscle pain) 

Diarrhea After Eating Final Thoughts

Postprandial diarrhea is a complex and often confusing condition which can often be a symptom of other more serious gastrointestinal conditions.

You cannot necessarily treat it like you can with the common cold, but there are steps you can take. 

Prevention is the best way to start. Maintaining a healthy lifestyle along with a hygienic environment can help reduce risk of gastrointestinal infections or stress/anxiety related postprandial diarrhea.

And as always, getting the right medical advice from your doctor is important. They will guide you in the evaluation and management of postprandial diarrhea. 

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Written and Medically Reviewed By

  • Sheila Jennings

    Sheila Jennings is a 4th-year medical student and also freelances as a content writer on gut health, nutrition, and food. She lives with IBS and has learned how to keep her symptoms at bay through a healthy diet and exercise. She wants to educate others on what they can do to take back control of their gut health and live like they used to.

  • Julie Guider, M.D.

    Dr. Julie Guider earned her medical degree from Louisiana State University School of Medicine. She completed residency in internal medicine at the University of Virginia. She completed her general gastroenterology and advanced endoscopy fellowships at University of Texas-Houston. She is a member of several national GI societies including the AGA, ACG, and ASGE as well as state and local medical societies.