Persistent Diarrhea: Why It Happens, How to Stop It, and When to Worry
By Stephanie Nwakaegho, Health Columnist At Gentechnews
A healthy digestive system quietly performs one of the most remarkable jobs in the human body. Every day, it breaks down food, takes in nutrients, and returns nearly all the water that passes through the intestines back into the body. Most people never think about it until something goes wrong.
If persistent diarrhea, or what many people call “constant purging,” develops, there’s a good chance the digestive system has stopped reabsorption (taking water back into the body) and has started pushing too much of it into the bowels where the stool is instead. This leads to frequent, watery bowel movements.
Not only is this inconvenient, but when left untreated, persistent diarrhea can lead to dehydration, loss of electrolytes (important body salts and minerals) poor nutrition, and in severe cases, it can become life-threatening.
Understanding why it’s happening is the first step toward stopping it.
What Happens Inside the Body During Persistent Diarrhea?
The digestive system handles about 9 litres of fluid every day. This includes everything consumed through food and drinks, as well as the digestive juices the body naturally produces.
Normally, the inside of the small intestine has the duty of taking almost all of this water back into the body before waste moves into the large intestine.
When diarrhea develops, that process no longer works as it should.
Instead of reabsorbing water back into the body, the intestines either begin releasing more water into the bowels or lose the ability to take enough water back in. As a result, stool becomes loose and watery and moves through the digestive system much faster than normal.
There are two main ways this happens.
Secretory Diarrhea
Certain bacteria, viruses, toxins), or inflammatory conditions cause the cells lining the intestines to release salts into the bowels. Water naturally follows these salts, filling the intestines with more fluid.
This is why some people continue passing watery stool even when they haven’t eaten anything.
Osmotic Diarrhea
Sometimes, certain foods or substances aren’t properly broken down or absorbed by the body.
These undigested substances pull water into the intestines, making the stool loose and watery. This often happens in people with lactose intolerance, some digestive disorders, certain medications, or when large amounts of artificial sweeteners are consumed.
In both cases, food moves through the digestive system too quickly, giving the body very little time to absorb the water and nutrients it needs.
Why Does the Purging Keep Coming Back?
Diarrhea should normally settle within a few days. When it doesn’t, there’s often an underlying problem that needs attention.
- Gastrointestinal Infections
One of the most common causes is an infection.
Viruses such as norovirus usually clear up within two or three days. However, bacterial infections caused by Salmonella, Campylobacter, certain strains of E. coli, or Clostridioides difficile (C. difficile) can last much longer.
Parasitic infections such as Giardia lamblia can also continue for weeks if they aren’t treated.
These germs damage the lining of the intestines or produce toxins that stimulate intestinal fluid secretion, causing large amounts of water to enter the bowels.
- Antibiotic-Associated Diarrhea
While antibiotics kill harmful bacteria, they also kill many of the good bacteria that naturally protect the digestive system.
This upsets the natural balance of bacteria in the gut, a condition known as Gut dysbiosis, which can lead to prolonged diarrhea and increase the risk of infections such as C. difficile.
- Food Intolerances
Some people cannot properly digest certain foods.
Common triggers include:
Milk and other dairy products (lactose intolerance)
Gluten in people with coeliac disease
Artificial sweeteners such as sorbitol
Large amounts of fructose found in some fruit juices
When these foods remain undigested in the intestines, they create an osmotic effect that draws water into the bowel, worsening diarrhea.
- Laxative Abuse and “Detox” Products
Many so-called detox teas and cleansing products contain stimulant laxatives such as senna or bisacodyl.
These ingredients stimulate the muscles of the intestines, making the bowels empty more often. This creates the false impression that the body is being “cleansed.” In reality, they simply speed up bowel movements and increase the loss of water and important minerals from the body.
Using them for a long time can damage the nerves that control the bowels, leading to ongoing diarrhea, dehydration, and loss of important body salts and minerals.
- Inflammatory Bowel Disease
Inflammatory bowel disease (IBD) is a group of long-term conditions that cause inflammation in the digestive system.
Crohn’s disease occurs when the immune system mistakenly attacks the digestive tract, causing inflammation that can affect any part of it, from the mouth to the anus.
Ulcerative colitis is a long-term condition that causes inflammation and sores (ulcers) in the lining of the large intestine and rectum.
Both conditions damage the lining of the intestines, making it harder for the body to take in water and nutrients.
Persistent diarrhea is often one of the earliest and most common warning signs.
Why Drinking Plain Water Isn’t Always Enough
Many people respond to diarrhea by drinking lots of water. While staying hydrated is important, water alone cannot replace everything the body is losing.
Every episode of diarrhea washes away important minerals, including:
Sodium
Potassium
Chloride
Bicarbonate
These minerals help the heart beat normally, keep the muscles working properly, support the nerves, and maintain the right balance of fluids in the body.
If only water is replaced without replacing these minerals, the sodium level in the blood can become too low. Leading to a condition, called hyponatremia which can be dangerous.
Why Oral Rehydration Solution (ORS) Works So Well
One of the greatest medical breakthroughs in treating diarrhea is Oral Rehydration Solution (ORS).
ORS works because the small intestine has a special system that allows glucose (sugar) and sodium to enter the body together. Even when the intestines are irritated or inflamed, this system continues to work.
As the glucose and sodium move into the cells lining the intestines, water follows them back into the bloodstream.
This is why ORS replaces lost fluids much better than plain water during diarrhea.
How to Rehydrate Properly
If persistent diarrhea develops, replacing lost fluids should be the first priority.
How To Use WHO-Recommended ORS
Commercial ORS packets contain the right balance of sugar and important minerals needed to help the body take in water effectively.
Simply mix the contents with clean water according to the instructions.
Homemade ORS
If an ORS packet isn’t available, a temporary solution can be made at home using:
1 litre of clean drinking water
6 level teaspoons of sugar
½ level teaspoon of salt
Mix well until everything dissolves.
Make sure not add extra sugar or salt. Using the wrong amounts can make diarrhea worse or increase the risk of dehydration.
Consider Zinc Supplements
Research shows that zinc supplements can reduce both the severity and the length of diarrhea, especially in children.
Adults may also benefit in some cases, but zinc should be used on the advice of a healthcare professional
Avoid Sugary Drinks
Fruit juices, soft drinks, and very sweet sports drinks contain too much sugar.
Instead of helping, they can pull even more water into the intestines and make diarrhea worse.
What Should You Eat?
The digestive system still needs nutrients to heal, so eating the right foods is important.
During the First 24 to 48 Hours
Choose foods that are easy on the stomach, such as:
Plain rice
Bananas
Toast
Plain crackers
Clear soups
Salted broth
Continue drinking ORS throughout the day.
As Symptoms Improve, Gradually add foods such as:
Boiled chicken
Eggs
Fish
Oats
Potatoes
Plain yoghurt (if dairy can be tolerated)
Protein helps the body repair the damaged lining of the intestines.
Can Probiotics Help?
Yes, in some cases, they can.
Probiotics are live, beneficial microorganisms, often called “good bacteria,” that help restore the natural balance of bacteria in the intestines after it has been disrupted by diarrhea or antibiotics.
Research shows that certain probiotic strains can shorten the duration of diarrhea and help the digestive system recover more quickly.
The probiotic strains with the strongest scientific evidence are:
Saccharomyces boulardii, a beneficial yeast that helps fight harmful germs in the intestines and is especially effective for antibiotic-associated diarrhea and infectious diarrhea.
Lactobacillus rhamnosus GG, a beneficial bacterium that helps restore the natural balance of gut bacteria and may reduce the duration of diarrhea.
Some commonly available probiotic products that contain these proven strains include:
FloraNorm® (Saccharomyces boulardii) (Beta Pharmacy)
Bioflor® (Saccharomyces boulardii CNCM I-745) (Greenbook NAFDAC)
Florastor® (Saccharomyces boulardii CNCM I-745)
Culturelle® (Lactobacillus rhamnosus GG)
These probiotics are particularly helpful for diarrhea that develops after taking antibiotics. However, they may not be suitable for everyone, especially people with severely weakened immune systems. It is always best to speak with a healthcare professional before starting any probiotic supplement.
When Should You See a Doctor?
Diarrhea often gets better on its own, but some symptoms should never be ignored.
Seek immediate medical care if any of the following occur:
Diarrhea lasting longer than three days without improvement
Severe dehydration
Inability to keep fluids down
High fever
Blood in the stool or black, tarry stools
Severe abdominal pain
Persistent vomiting
Passing little or no urine
Confusion, dizziness, or fainting
Rapid, unexplained weight loss
Young children, older adults, pregnant women, and people with weakened immune systems should seek medical care much sooner because they can become dehydrated more quickly.
Can Persistent Diarrhea Be Prevented?
While not every case can be prevented, the risk can be reduced by:
Washing hands thoroughly before eating and after using the toilet.
Drinking clean, safe water.
Cooking meat and seafood properly.
Washing fruits and vegetables before eating them.
Avoiding unnecessary use of antibiotics.
Practising good food hygiene, especially when eating outside the home.
Properly managing long-term digestive conditions with regular medical check-ups.
Nurses Insight
Persistent diarrhea is more than just frequent trips to the toilet. It is a sign that something isn’t working properly in the digestive system. As the intestines become less able to absorb water and nutrients, the body loses the fluids and nourishment it needs to function properly. If left untreated, this can lead to dehydration, weakness, and poor nutrition.
Whether it’s caused by an infection, food intolerance, inflammatory bowel disease, antibiotic use, or another underlying condition, ignoring persistent diarrhea can lead to serious complications.
The good news is that many cases improve with proper rehydration, good nutrition, and early treatment of the underlying cause. Oral Rehydration Solution (ORS) remains one of the most effective ways to replace lost fluids and important minerals, while recognising warning signs early can prevent severe dehydration and other life-threatening complications.
The digestive system is remarkably resilient, but when it keeps sending warning signs, it’s worth paying attention. Persistent diarrhea isn’t something to simply “wait out.” Understanding what’s happening inside the body and taking the right steps early can make all the difference to recovery.
Stephanie Nwakaegho is a Registered Nurse and Registered Public Health Nurse with the Nursing and Midwifery Council of Nigeria, and a health columnist at Gentechnews. She writes on clinical practice, public health, and healthcare systems, translating evidence into practical, human-centered health stories. She can be reached at thestephanienwakaegho@gmail.com.