Causes and Treatment of Persistent Diarrhea: When Should You Be Concerned?

Are you or one of your children suffering from persistent and recurrent diarrhea? Are you trying to figure out the cause and how to get rid of it? Diarrhea is a common problem that affects many people. It often resolves on its own within a day or two, but it may require medical intervention if it lasts longer, as it can lead to serious complications like severe dehydration. Keep reading this article to learn more about the causes and treatment of persistent diarrhea.

The Difference Between Acute, Chronic, and Persistent Diarrhea

Diarrhea is defined as passing loose or watery stools three or more times within 24 hours. It’s a common condition that can affect anyone at some point in their life. Diarrhea is classified by duration into three types:

• Acute diarrhea: Lasts for one or two days and often resolves on its own without medical treatment.

• Persistent diarrhea: Lasts from two to four weeks.

• Chronic diarrhea: Persists or recurs for more than four weeks and may indicate an underlying chronic condition such as irritable bowel syndrome, inflammatory bowel diseases, or malabsorption syndromes.

The Problem of Persistent Diarrhea and Its Impact on Health

Diarrhea, regardless of its cause, can lead to several complications, most notably:

• Dehydration and mineral loss: Due to fluid loss, the body may lose important electrolytes like sodium, potassium, magnesium, and chloride, which can result in severe dehydration or even circulatory collapse, especially in children, the elderly, and those with severe diarrhea such as cholera.

• Metabolic acidosis: May occur due to the loss of bicarbonate with the stool.

• Potassium deficiency: Can happen in acute or chronic diarrhea, particularly when stools contain large amounts of mucus.

• Magnesium deficiency: Prolonged diarrhea can lower blood magnesium levels, leading to muscle cramps.

Causes of Persistent Diarrhea Across Different Age Groups

The causes of diarrhea may differ between children and adults, although some causes are shared. Below are the causes of persistent diarrhea in children and adults:

Causes of Persistent Diarrhea in Children

Diarrhea occurs when the body fails to remove enough water from the child’s stool during digestion, or when large amounts of fluid are secreted into it, making it soft or watery.

There are various causes of diarrhea, some temporary like infections, and others related to chronic or ongoing conditions:

1. Viral infections (viral gastroenteritis)

• One of the most common causes, caused by viruses such as rotavirus and norovirus, and spreads easily.

• It often begins with vomiting, followed by diarrhea that can last up to 10 days, sometimes with mild fever.

2. Bacterial infections

• Some types of bacteria, such as Salmonella, Shigella, and E. coli, can cause intestinal inflammation.

• Symptoms may appear suddenly and include blood or mucus in the stool and fever.

3. Parasites

• Certain parasites like Giardia and Cryptosporidium can cause persistent diarrhea along with symptoms such as abdominal pain, nausea, and loss of appetite.

• These parasites are common in natural water sources and in specific regions.

4. Antibiotics

• Some antibiotics can disrupt the balance of gut bacteria, leading to diarrhea.

• In rare cases, harmful bacteria like Clostridioides difficile can overgrow and cause severe symptoms like abdominal pain, fever, and bloody stools.

• A doctor should be consulted if these symptoms appear.

5. Chronic constipation

In some cases, chronic constipation can cause watery stool leakage and soiling of the child’s underwear.

6. Lactose intolerance

This is the inability to digest lactose in milk.

It may cause diarrhea and abdominal pain, especially after a bout of viral gastroenteritis.

Consult a doctor before making any dietary changes.

7. Inflammatory bowel disease (Crohn's disease and ulcerative colitis)

Chronic conditions that can cause episodes of diarrhea and other symptoms such as weight loss.

8. Celiac disease

An immune disorder in which the body is sensitive to gluten, leading to diarrhea, abdominal pain, bloating, and poor growth.

9. Malabsorption

Occurs when the body cannot properly absorb nutrients from food, leading to chronic diarrhea and difficulty gaining weight.

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Causes of Persistent Diarrhea in Adults

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), diarrhea may last more than a week, and persistent diarrhea could indicate underlying health conditions that require medical evaluation.

Here are the most common causes of persistent diarrhea in adults:

1. Infections

• This is the most common cause of persistent diarrhea. It can result from viral, bacterial, or parasitic infections.

• These infections can spread through contaminated food or water, or due to poor hygiene. Examples include:

Traveler’s Diarrhea

Caused by consuming contaminated food or drink while traveling to areas with poor sanitation. It’s often acute, but certain parasitic infections can lead to prolonged symptoms.

2. Lactose Intolerance

• Occurs due to a deficiency of the enzyme lactase, responsible for digesting milk sugar (lactose).

• Undigested lactose draws water into the intestines, causing diarrhea, gas, and abdominal pain.

3. Celiac Disease

• An autoimmune disorder that damages the intestinal lining upon consuming gluten.

• It leads to poor nutrient absorption and chronic diarrhea, and may be accompanied by anemia, fatigue, and weight loss.

4. Crohn’s Disease

• A type of chronic inflammatory bowel disease (IBD) that can affect any part of the digestive tract.

• It disrupts fluid absorption, resulting in frequent, watery stools.

5. Irritable Bowel Syndrome (IBS)

• A disorder affecting bowel motility, causing rapid muscle contractions that reduce water absorption and lead to diarrhea.

• It’s often linked to stress, food poisoning, or bacterial imbalance.

6. Medication Side Effects

Certain medications may cause diarrhea as a side effect, including:

• Antibiotics, which can disrupt gut microbiota.

• Antacids containing magnesium.

• Blood pressure medications.

• Cancer treatments.

Causes of Persistent Diarrhea Immediately After Eating

Some individuals experience sudden diarrhea shortly after eating, often accompanied by discomfort or urgency.

Causes may include infections, antibiotics, or digestive diseases like IBD. Notable causes include:

1. Irritable Bowel Syndrome (IBS)

• A common digestive disorder causing bloating and cramps, with symptoms varying between constipation (type C) and diarrhea (type D).

• Affects around 10–15% of the global population. Dietary changes, medications, and stress management can ease symptoms.

2. Inflammatory Bowel Diseases (IBD)

• Autoimmune conditions where the immune system attacks healthy intestines, causing inflammation and irritation.

• Examples include Crohn’s disease and ulcerative colitis, leading to chronic diarrhea, cramps, weight loss, and fatigue.

3. Endocrine Disorders

Hormonal issues such as hyperthyroidism or diabetes may cause chronic diarrhea, especially when the digestive nerves are affected.

4. Celiac Disease

• An autoimmune condition affecting gluten absorption—a protein found in wheat, barley, and rye.

• Gluten ingestion causes diarrhea and other digestive symptoms.

• Patients should read food labels carefully to avoid gluten, which may be found in products like pasta, bread, sauces, and broths.

Types and Causes of Persistent Diarrhea

The main types of persistent diarrhea and their causes include:

1. Osmotic Diarrhea

• Water absorption in the intestines depends on the absorption of dissolved substances.

• When poorly absorbed substances remain in the gut, they draw in water and cause diarrhea. Causes include:

• Poorly absorbed substances like sorbitol, mannitol, and some antacids.

• Malabsorption conditions like lactose intolerance due to lactase deficiency, which causes water retention and fermentation in the colon, resulting in gas.

2. Secretory Diarrhea

• Normally, water is secreted in the small intestine and then reabsorbed.

• When secretion increases or absorption decreases, diarrhea occurs. Causes include:

• Cholera infection, which produces toxins that increase water secretion.

• Use of certain laxatives.

• Hormonal secretion from tumors.

• Certain medications.

• Substances like arsenic, caffeine, pesticides, and fungal toxins.

3. Inflammatory or Infectious Diarrhea

• Occurs when the intestinal lining is damaged by invading viruses, bacteria, or parasites, impairing absorption. Common causes include:

• Bacteria: Salmonella, E. coli, Campylobacter.

• Viruses: Rotavirus, coronavirus, norovirus.

• Parasites: Coccidia, Cryptosporidium, Giardia.

4. Diarrhea from Altered Gut Motility

• For water and nutrients to be absorbed, they must remain in the gut long enough.

• When motility increases—as seen in certain neurological conditions or with some medications—absorption time is reduced, resulting in diarrhea even if the absorptive mechanism itself is intact.

5. Fatty Diarrhea (Steatorrhea)

• Occurs when fats are not properly digested or absorbed, or when intestinal bacteria produce large amounts of fatty acids.

• This type is less frequent but more voluminous, with a strong odor and visible greasy residue in the toilet.

• It may be accompanied by nausea, indigestion, and weight loss.

Diagnosis of Persistent Diarrhea

A doctor is likely to ask questions about the patient’s medical history, review their current medications, conduct a physical examination, and possibly order tests to determine the cause of the diarrhea. These tests may include:

• Blood tests: Such as a complete blood count, electrolyte levels, and kidney function tests to assess the severity of the condition.

• Stool analysis: Used to detect bacteria or parasites that may be causing the diarrhea.

• Hydrogen breath test: Helps diagnose lactose intolerance. After consuming a lactose-rich drink, hydrogen levels in the breath are measured periodically; elevated levels indicate poor lactose absorption.

• Sigmoidoscopy or full colonoscopy: A thin, flexible tube with a camera is used to examine the lining of the colon. A biopsy (tissue sample) may be taken. Sigmoidoscopy views the lower colon, while colonoscopy allows examination of the entire colon.

• Upper endoscopy: A flexible tube with a camera is inserted through the mouth to examine the stomach and upper small intestine. A biopsy may also be taken for lab analysis.

Treatment of Persistent Diarrhea

Treatment depends on the underlying cause, but there are general home care steps to ease symptoms, along with specialized treatment options when necessary:

1. Home Treatment

Over-the-counter medications

Certain medications can help reduce bowel movements and relieve symptoms, such as:

• Loperamide: Slows intestinal movement, reducing bowel frequency.

• Bismuth subsalicylate: Coats the intestinal lining and helps eliminate some bacteria.

Diet modification

• Eat bland, easy-to-digest foods, including:

• Bananas, rice, applesauce, toast (BRAT diet).

• Cooked vegetables, scrambled eggs, broth, skinless chicken or turkey, white bread, white rice, oats.

• Avoid certain foods like:

• Fried, fatty, or spicy foods.

• Milk and dairy (except yogurt and kefir).

• Red meat, fish, citrus fruits, raw vegetables, sweets.

• Carbonated drinks, caffeine, alcohol, and overly hot or cold beverages.

• Rehydration: To replace lost fluids and electrolytes, drink:

• Water.

• Low-sugar natural juices.

• Sports drinks or oral rehydration solutions.

• Clear broths.

• Avoid beverages like:

• Coffee, tea, alcohol, and artificially sweetened drinks (e.g., diet soda).

• Low-FODMAP diet: Consider trying this to identify food triggers, especially in cases of irritable bowel syndrome (IBS).

Medication adjustment

If the patient is on regular medication, it's essential to consult a doctor to determine if the drugs could be causing the diarrhea, and discuss possible changes or dosage adjustments.

2. Medical Treatment When Needed

If symptoms persist despite home care, medical intervention may be required. Treatment depends on the cause and may include:

• Anti-diarrheal medications like loperamide.

• Specific drugs: such as clonidine (for diabetes-related cases) or eluxadoline (for IBS).

• Antibiotics or antiparasitic medications if an infection is the cause.

• Bile acid binders if bile acids are contributing to the diarrhea.

• Fiber supplements like psyllium to bulk up the stool.

Seek immediate medical attention if diarrhea lasts more than a few days or is accompanied by alarming symptoms such as fever, dehydration, or blood in the stool.

When to See a Doctor

While diarrhea is often mild, it can become serious if it leads to severe dehydration or signals a more serious illness. It’s important to recognize warning signs that require urgent medical care.

For adults or children under your care, seek medical attention if you notice

• Behavioral or mental status changes (e.g., lethargy or irritability).

• Frequent vomiting.

• Severe abdominal or rectal pain.

• Black, tar-like stools, or stool with blood or pus.

• Signs of dehydration (e.g., excessive thirst, dry mouth, reduced urination, dizziness).

Additional warning signs for adults include

• Diarrhea lasting more than 2 days.

• High fever.

• More than 6 episodes of diarrhea per day.

Certain individuals are more vulnerable to complications and should maintain regular contact with a healthcare provider:

• Pregnant women or those over age 65.

• Those currently using antibiotics.

• People with weakened immune systems.

Additional warning signs for infants and children include

• Diarrhea lasting more than 24 hours.

• Any fever in infants, or high fever in older children.

• Refusal to eat or drink for several hours.

• Excessively frequent watery stools.

• Inability to drink enough fluids or oral rehydration solutions.

Diarrhea in infants, especially newborns, can lead to severe dehydration within a day or two and may become life-threatening if not treated. Call a doctor immediately if:

• The child is under one year of age.

• Was born prematurely.

• Has chronic health conditions.

• Cannot continue drinking fluids.