Paradoxical Diarrhea or Overflow Diarrhea

This type of diarrhea is really due to having constipation

It is possible to have diarrhea and constipation at the same time. This is called paradoxical diarrhea or overflow diarrhea. It happens when watery stool leaks out around hard stool in the rectum.

This article looks at paradoxical diarrhea, its causes, and treatment. It also offers suggestions for how to prevent paradoxical diarrhea.

A woman holds a hot water bottle against her abdomen as though she's in pain.
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Understanding the Digestive System

Food nourishes our bodies and gives us fuel. In order for food to become something our cells can use, it needs to be digested.

The digestive system begins in the mouth and continues on through the body. It includes the esophagus, stomach, intestines, and anus, where stool leaves the body. 

Digestion begins in the mouth. As you chew your food, the enzymes in your saliva start breaking it down. That process continues throughout the digestive tract.

Chewed food is swallowed and moves down the esophagus into the stomach. In the stomach, digestive juices break the food down more. The stomach muscles mix everything together.

From there, the food moves into the small intestine. More digestive juices are added to the mix. At this point, nutrients are absorbed so they can be used by the body. 

What’s left goes into the large intestine. In the large intestine, water is absorbed from the stool, making it thicker.

The stool is held the rectum until the body has an urge to have a bowel movement. During a bowel movement, the stool is passed out of the body.

This is the way the digestive process functions when everything is working well. Bowel movements vary from person to person in terms of frequency and consistency. Every person will have their own version of “normal.”

There are many reasons why the digestive system may have trouble. When things go wrong, it could result in constipation and/or diarrhea.


As food travels through your body, digestive juices help break it down so your body can absorb the nutrients. At the end of the process, it's expelled from your body as stool. 

What Causes Diarrhea

Diarrhea is when you have liquid stools three or more times in a day. It is a common digestive problem. It can affect anyone at all stages of life.

There are many possible causes of diarrhea. This may make it difficult to diagnose and treat. Even so, diarrhea usually only lasts a few days and goes away on its own.

In many cases, diarrhea that lasts for a few days is caused by an infection with a parasite, virus, or bacteria.

Viruses that cause diarrhea spread rapidly from person to person. If you come down with diarrhea after a close contact like a family member has had it, it might mean there’s a virus going around.

Bacteria can also cause diarrhea. Many of these are spread through food or water. They cause illnesses referred to as foodborne disease or “food poisoning."

Parasites can also cause diarrhea. These parasites are not common in developed parts of the world. They may be more common in developing areas.

Outside of viruses, parasites, and bacteria, there are many other diseases and conditions that can cause diarrhea. These include:

These conditions are causes of chronic diarrhea. Chronic means it goes on for more than a few days.

Some medications like antibiotics can also cause diarrhea. This usually clears up after you stop taking the drug.


Diarrhea can be caused by viruses, bacteria, or parasites. Some medical conditions like IBS and celiac disease can also cause diarrhea. 

What Causes Constipation?

If you have a bowel movement fewer than two or three times a week, you may have constipation. When you have constipation, your stool tends to be hard. It is also difficult and sometimes even painful to pass. You may need to strain or push to have a bowel movement.

Constipation might occur for just a few days. It could also be chronic and occur over a long period of time.

Constipation is common in children. Adults may experience it a few times a year.

Some causes include not eating enough fiber or drinking enough water and a low level of physical activity. Traveling or stress can also cause some people to become constipated.

Medications are also a major cause of constipation. This is especially true in older adults. Some medications that may cause constipation include:

Conditions that may cause constipation include:

Colon cancer is also linked to constipation, but it is not a common cause. With colon cancer there may be other symptoms like blood in the stool, pain, weight loss, or fatigue.


Constipation can be caused by what you eat or drink. It may also happen because of a low level of physical activity. Some medications and certain medical conditions can also cause constipation.

How Constipation Causes Paradoxical Diarrhea

Many people with diarrhea assume it's caused by a virus or something they've eaten. Most people don't realize that diarrhea can actually be caused by constipation. 

Constipation may only last for a few days. In some cases, though, it can become chronic. When you don't pass stool for an extended period of time, it may build up in the digestive tract. This can result in what’s called fecal impaction.

Fecal impaction is when there is a large, hard mass of stool in the intestine. This stool is so hard and so stuck that it can’t be passed.

Fecal impaction might also be called impacted stool, impacted bowel, or impacted colon.

A person who has a fecal impaction may find they have watery stools but are not really moving their bowels. In fact, it might be difficult to contain the stool in the rectum. It may leak, leading to bathroom accidents or incontinence.

This happens because there is watery stool behind the fecal impaction. It is seeping out around the hard mass of stool. This liquid stool is often foul-smelling.

This can lead some people to think they’re having diarrhea when the real problem is the impacted stool.

The problem is worsened when the rectum is distended, or enlarged. The internal anal sphincter muscle relaxes and stool leaks out. This happens because of the greater volume of stool.

The large intestine may respond by producing more fluid. This results in even more watery stool that can’t be contained.


Paradoxical diarrhea happens when watery stool leaks out around a fecal impaction. 

Causes of Fecal Impaction

Laxatives are medicines that can help you have a bowel movement when you're constipated.

Some types of laxatives are safe to use long-term. Others can cause dependence. This means that long-term use of certain laxatives may lead to your body being unable to have a bowel movement without them.

Laxatives that are usually safe for long-term use include:

Stimulant laxatives and stool softeners aren't usually recommended for long-term use. Stimulant laxatives increase the movements of the muscles in the intestine. Stool softeners cause more water to be drawn into the intestine.

When these kinds of laxatives are stopped, the constipation may return or to get worse. Eventually, this could lead to fecal impaction.

Fecal impaction is a significant problem for older adults. This is especially true for those in care facilities.

Some pain medications such as opioids can contribute to constipation. This is because they slow down the action of the bowel. People who are bedridden or otherwise unable to move around may also develop constipation and/or fecal impaction.


Stimulant laxatives and stool softeners may lead to dependency, causing long-term constipation. Pain medications like opioids or long-term immobility can also cause chronic constipation. This can lead to fecal impaction. 

Paradoxical Diarrhea In Children

In children, holding in bowel movements can lead to constipation. This can result in a cycle of painful bowel movements.

Encopresis is when children have bathroom accidents or soil their underwear with stool. Constipation may lead to encopresis.

A child might hold bowel movements in order to avoid the pain, which leads to more constipation. This may lead to impaction and liquid stool that leaks from the rectum.

Kids who experience encopresis may go to the bathroom infrequently. When they do go, they may have hard, small stools.

Parents may think children with encopresis have diarrhea, when, in fact, the children are unable to control stool leakage that occurs because of constipation.

To avoid this, make sure children:

  • Drink enough water
  • Eat more foods that contain fiber
  • Eat fewer foods that may contribute to constipation, like bread, bananas, rice, and cheese

In some children, there may be a behavior component. If your child is soiling their underwear, your pediatrician can help you understand how to treat the problem.


Children may hold in their stools. This can lead to a cycle of constipation and fecal impaction. Sometimes, soiling accidents are actually paradoxical diarrhea.

Removing an Impaction

In some cases, the hard mass of stool in the rectum can be removed manually. This means a doctor can dislodge the stool with a gloved, lubricated finger.

An anoscope is a tool used to look inside the anus. This may also help a doctor remove the stool.

A fecal impaction may also be removed with an enema. This might be done when the impaction is not as close to the anus.

The enema may need to be given by a healthcare professional. Special tools can ensure that the enema liquid goes further into the digestive tract.

Sometimes impacted stool may be higher in the digestive tract. If it can't be reached with an enema, laxatives might be used.

Uncommonly, surgery to remove the fecal matter may be necessary. This is considered more often for those who have had prior surgery on the anal area. This may include surgery on anal fistulas or hemorrhoid removal.


A fecal impaction may be removed manually by a doctor. An enema may also help to pass it. Laxatives may be used for impactions that are higher in the digestive tract. In rare cases, surgery may be needed.

Preventing Paradoxical Diarrhea

You can prevent paradoxical diarrhea by preventing constipation. This may mean making diet and lifestyle changes.

An important first step is to never ignore the urge to have a bowel movement. Drinking more water can help keep your stools soft. To get more fiber in your diet, eat foods such as:

  • Whole grains
  • Legumes
  • Fruits
  • Vegetables
  • Nuts

Fiber supplements are bulk-forming laxatives. These may also be used to keep stools soft and easily passed.

Stimulant laxatives might help prevent constipation. However, it is important to ask a doctor before you take these. This is because of the risks involved in using them long-term.

For short-term use, these laxatives are often safe. If your constipation lasts more than a few days, it is important to find and address its cause rather than keep using laxatives.

Some people also use enemas for constipation. It's important to note that long-term use of enemas can have risks.

Using an enema once in a while shouldn’t be a problem. They are not a solution for chronic constipation, though.


Diet and lifestyle changes can help prevent fecal impaction and paradoxical diarrhea. Bulk-forming laxatives may also help. Stimulant laxatives and enemas are fine for occasional use, but should not be used long-term.

When to See a Doctor

Diarrhea and/or constipation that comes and goes for a few days isn't usually cause for concern. See a doctor, though, if you also have any of these symptoms:

Constipation that goes on long enough to cause paradoxical diarrhea may need treatment. You may need to find out why you have constipation in order to stop it from happening again.

This is especially true if bulk-forming laxatives or lifestyle changes don't fix the problem.


Occasional diarrhea or constipation is usually nothing to worry about. See a doctor if you also have symptoms like dehydration, blood in the stool, or severe abdominal pain.


Paradoxical diarrhea is caused by a fecal impaction, a hard stool that is "stuck" in the colon. Constipation that lasts for a long time may lead to fecal impaction. Sometimes, watery stool can leak around the impaction. Long-term use of stimulant laxatives or stool softeners can contribute to this problem.

A fecal impaction can be removed manually or with an enema. Rarely, surgery may be necessary. You can prevent paradoxical diarrhea by taking steps to avoid constipation. Eat plenty of fiber, drink more water, and use bulk-forming laxatives. 

See a doctor if you have constipation with other symptoms like dehydration, dizziness, or severe abdominal pain. 

A Word From Verywell

Diarrhea and constipation are common. That doesn’t mean they can’t be serious.

Hard stools that lead to impaction and overflow diarrhea can be uncomfortable, messy, and embarrassing. Chronic constipation is a reason to work with a doctor. Once the cause is found, you can move towards a long-term solution.

For older adults, especially those in care facilities, constipation should be addressed right away. Paradoxical diarrhea is a problem, but fecal impaction and the treatment for it have the potential to cause long-term complications.  

Frequently Asked Questions

  • Can fecal impaction cause other complications?

    Yes, more severe complications can occur if the impaction is not cleared. Impaction causes increased colon pressure. This can lead to ulcers and colon perforation. Fecal impaction can also cause compression of nearby nerves and organs.

  • What are the best natural ways to avoid fecal impaction?

    You can avoid fecal impaction in the same way you avoid constipation. Eat a fiber-rich diet and drink plenty of fluids. If this is a regular issue, a doctor may advise the use of stool softeners or laxatives. Your doctor may also adjust any medications that lead to constipation.

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10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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