Chronic Diarrhea: 11 Causes & How to Treat It

Chronic diarrhea is a condition characterized by frequent, loose, or watery stools that last for 4 weeks or longer. It can be caused by conditions such as food intolerance, intestinal infections, irritable bowel syndrome, or inflammatory bowel diseases like Crohn’s disease.

Chronic diarrhea may also be linked to pancreatic disorders, medication use, or conditions like celiac disease and small intestinal bacterial overgrowth (SIBO). Symptoms can vary based on the cause and may include abdominal pain, gas, weight loss, or changes in stool appearance.

Treatment for chronic diarrhea depends on the underlying condition and may include dietary changes, hydration, probiotics, or medications such as antibiotics, immunosuppressants, or enzyme replacements. Identifying the cause is essential to guide proper treatment and improve symptoms.

Main causes

Chronic diarrhea can be caused by the following conditions:

1. Food intolerances or allergies

Some food intolerances, such as lactose or gluten intolerance, or an allergy to milk protein, can irritate and inflame the intestine and lead to chronic diarrhea.

Other symptoms may include excess gas, nausea, or abdominal cramps.

How to treat: it is important to try to identify the food causing the intolerance and see a gastroenterologist to confirm the diagnosis. A registered dietitian can also help create an individualized diet plan.

2. Intestinal infections

Some intestinal infections, such as giardiasis, amebiasis, or ascariasis, as well as bacterial and viral infections, can cause chronic diarrhea when they are not identified early.

Other symptoms of intestinal infections include abdominal pain, increased gas, fever, or vomiting.

How to treat: rest and eat easy-to-digest foods. According to the CDC, oral rehydration solution is an important part of diarrhea treatment because it helps replace fluids and electrolytes lost through stool.

It is also important to see a gastroenterologist, who may prescribe antibiotics or antiparasitic medications depending on the cause of the infection.

3. Irritable bowel syndrome

Irritable bowel syndrome (IBS) can cause changes in the intestine that lead to chronic diarrhea, excess gas, abdominal pain, and bloating.

These symptoms can vary in intensity. They may appear suddenly, last for a period of time, and then go away.

How to treat: IBS treatment should be guided by a gastroenterologist and may involve dietary changes and/or the use of probiotics or antidepressant medications to relieve symptoms.

4. Medication use

Some medications can alter gut bacteria, intestinal movement, and the intestinal lining, causing diarrhea as a side effect.

These medications include antibiotics, some antidepressants, cancer drugs, omeprazole, and lansoprazole, for example.

How to treat: if diarrhea is caused by antibiotics, probiotics may help manage symptoms by supporting gut flora and intestinal function. If diarrhea is caused by other medications, it is best to speak with the healthcare provider who prescribed the medication.

It is also important to eat easy-to-digest foods and stay hydrated to help improve diarrhea.

5. Crohn’s disease

Crohn’s disease is an inflammatory bowel disease that causes chronic inflammation of the intestinal lining.

This disease can cause chronic diarrhea, which may look yellow due to poor nutrient absorption. It can also cause abdominal pain or stools with blood or mucus.

How to treat: treatment should be guided by a gastroenterologist and usually involves corticosteroids, immunosuppressants, or biologic therapy, along with changes in eating habits.

In some cases, the doctor may also recommend surgery to remove damaged parts of the intestine.

6. Ulcerative colitis

Ulcerative colitis is another inflammatory bowel disease that causes inflammation, sores, or ulcers in the intestinal wall. This can lead to bleeding and chronic diarrhea with bright red, brown, or black blood, as well as a foul smell.

Other symptoms include abdominal pain, mucus in the stool, fever, excess gas, or anemia.

How to treat: treatment should be guided by a gastroenterologist and varies depending on symptom severity. Immunosuppressive medications, biologic therapy, or even surgery may be recommended.

7. Celiac disease

Celiac disease is a severe reaction to gluten that causes intestinal irritation and poor absorption. This increases how quickly stool moves through the intestine, leading to chronic diarrhea and increased fat in the stool.

People with celiac disease usually notice symptom improvement when they remove foods with gluten from their diet.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, gluten is a protein found in wheat, barley, and rye that triggers damage to the small intestine in people with celiac disease.

How to treat: it is important to see a gastroenterologist to confirm the diagnosis and start a gluten-free diet. In some cases, the doctor may also prescribe immunosuppressive medications.

8. Pancreatic diseases

Pancreatic diseases, such as pancreatic insufficiency, chronic pancreatitis, or pancreatic cancer, can impair food digestion due to a lack of digestive enzymes.

This mainly affects fat absorption, causing chronic diarrhea that may be pasty, shiny, or greasy.

How to treat: pancreatitis treatment should be guided by a gastroenterologist, who may prescribe pancrelipase. This medication replaces digestive enzymes and helps improve digestion and nutrient absorption, which can improve diarrhea.

It is also important to see a registered dietitian to develop a nutrition plan tailored to the person’s condition. This can help improve nutrient absorption, prevent weight loss and possible malnutrition, and relieve discomfort caused by these diseases.

9. Cystic fibrosis

Cystic fibrosis is a genetic disease that affects the cells that produce mucus, especially in the lungs and intestines. This makes mucus thicker and stickier, which can lead to alternating periods of diarrhea and constipation.

Other symptoms include fatty, foul-smelling stools, poor digestion, or weight loss.

How to treat: treatment for cystic fibrosis is usually done with medications prescribed by a doctor and nutritional follow-up to help control the disease and improve quality of life.

10. Colon cancer

Colon cancer can cause symptoms such as frequent diarrhea, weight loss, abdominal pain, fatigue, and blood in the stool.

These symptoms can vary depending on the location of the cancer and how advanced it is.

How to treat: if these symptoms last for more than 1 month, or if the person is over 50 or has a family history of colon cancer, it is important to see a gastroenterologist.

Treatment for colon cancer usually involves surgery, chemotherapy, and/or radiation therapy.

11. Small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) can cause chronic diarrhea, intestinal cramps, or even malnutrition.

This condition is caused by excessive bacterial growth in the small intestine. It may happen due to problems with intestinal movement, low stomach acid, or medication use.

How to treat: treatment is guided by a gastroenterologist and usually involves antibiotics, dietary changes, or probiotics.

What to eat

Foods that can help manage chronic diarrhea and keep it from getting worse include:

• Soups and purees made with cooked vegetables that do not stimulate the intestine, such as pumpkin, carrots, zucchini, chayote, potatoes, or sweet potatoes

• Green bananas and cooked or baked fruits, such as apples, peaches, or pears

• Rice or corn porridge

• Cooked rice

• Baked or grilled white meats, such as chicken or turkey

• Baked or grilled fish

It is also important to drink about 2 liters of fluids per day, such as water, tea, coconut water, or strained fruit juices. Homemade oral rehydration solution or oral rehydration salts found in pharmacies may also be used.

When you have chronic diarrhea, it is important to see a registered dietitian to adapt your diet to the underlying condition. A registered dietitian can also assess whether nutritional supplements are needed to help maintain or regain weight and support adequate vitamin and mineral intake.