10 Common Causes of Chronic Diarrhea in Adults

Key takeaways:

• Chronic diarrhea often has underlying causes, ranging from digestive issues to dietary habits. Recognizing these can help with targeted treatment.
• Certain chronic conditions, like IBS or IBD, can lead to ongoing digestive problems that require medical management.
• Persistent diarrhea may indicate a more serious health issue, so consulting a healthcare provider can ensure timely diagnosis and treatment.

Chronic diarrhea, which means frequent, loose stools that stick around for more than a month, can be both frustrating and disruptive. Unlike the occasional bout of digestive trouble, ongoing diarrhea often hints at underlying issues that may need attention.

Learning about possible causes—like certain foods, digestive conditions, or lingering infections—can be a helpful first step in figuring out what might work to ease symptoms. In this article, we’ll look at some common reasons for chronic diarrhea in adults, treatment tips to try at home, and signs that a check-in with a healthcare provider might be a good idea.

Common causes of chronic diarrhea

Chronic diarrhea may stem from a variety of causes, each with its unique set of symptoms and recommended treatments. Here are some frequent contributors to long-term digestive issues in adults:

1. Irritable bowel syndrome (IBS)

IBS, especially IBS-D (Irritable bowel syndrome with diarrhea), is one of the most common causes of chronic diarrhea. This condition affects the large intestine, leading to symptoms such as abdominal pain, bloating, gas, and frequent, loose stools. Stress, certain foods, and hormonal changes can trigger symptoms in people with IBS.

Managing IBS typically involves dietary adjustments, like following a low-FODMAP diet, and using medications or stress management techniques. Working with a gastroenterologist can provide a tailored approach to alleviate symptoms.

2. Irritable bowel disease (IBD)

IBD, including Crohn's disease and ulcerative colitis, is a chronic inflammatory disorder of the digestive tract. Both conditions cause inflammation in the intestines, leading to symptoms like abdominal pain, weight loss, and diarrhea. In Crohn’s disease, inflammation can affect any part of the digestive tract, while ulcerative colitis is limited to the colon.

IBD typically requires ongoing medical management, including medications to control inflammation and regular check-ups with a healthcare provider. If you experience prolonged diarrhea, unexplained weight loss, or blood in the stool, seeking medical advice for possible diagnostic work-up and treatment is essential.

3. Food intolerances and sensitivities

Some individuals experience chronic diarrhea due to food intolerances, such as lactose or gluten intolerance. When the body struggles to process certain substances—like lactose (a sugar in dairy) or gluten (a protein in wheat)—digestive symptoms like gas, bloating, and diarrhea often occur after consumption of trigger foods.

Identifying and avoiding trigger foods can help prevent symptoms. Working with a dietitian or healthcare provider can support a balanced diet while managing these intolerances.

4. Trouble absorbing bile acids

When the intestines have trouble absorbing bile acids—important for breaking down fats—it can lead to chronic diarrhea along with bloating, gas, and general stomach discomfort. Bile acid malabsorption is sometimes confused with other digestive issues, like IBS, due to its similar symptoms, so seeking medical attention is key to help differentiate the underlying cause.

A healthcare provider may recommend medications that bind to bile acids, helping reduce diarrhea. Diagnosing this condition typically involves specific tests, so consulting a specialist can ensure effective management.

5. Chronic infections

Chronic infections, such as those caused by certain bacteria, parasites, or viruses, can lead to long-term diarrhea. Giardiasis (caused by Giardia) and Clostridium difficile (C. diff) are examples of infections that may persist and require specific treatment.

If chronic diarrhea follows travel, contact with untreated water, or recent antibiotic use, a healthcare provider can conduct tests to determine if an infection is present. In many cases, antibiotics or other targeted treatments may be needed.

6. Medications and long-term antibiotic use

Some medications, including long-term antibiotics, certain antidepressants, and diabetes medications, can disrupt the balance of gut bacteria and lead to chronic diarrhea. Antibiotic-associated diarrhea, for instance, may occur due to a reduction in healthy gut flora.

If you suspect a medication is causing diarrhea, consult your healthcare provider. Adjustments in dosage or switching to an alternative treatment may help. Taking a probiotic may also support gut health during or after antibiotic treatment.

7. Celiac disease

Celiac disease is an autoimmune disorder in which gluten consumption damages the small intestine, leading to symptoms such as chronic diarrhea, bloating, and malnutrition. People with celiac disease experience an immune response to gluten that can cause persistent digestive discomfort if left untreated.

Avoiding gluten is essential for managing celiac disease. Diagnosis typically involves blood tests and possibly a biopsy of the small intestine.

8. Pancreatic enzyme deficiency

Pancreatic enzyme deficiency happens when the pancreas doesn’t release enough enzymes to fully digest food. This leads to chronic diarrhea, greasy or oily stools, and sometimes weight loss, as the body struggles to absorb nutrients. Conditions like chronic pancreatitis or cystic fibrosis often cause this issue.

Treatment often includes pancreatic enzyme replacement therapy (PERT) and adjustments to diet, helping the body break down and absorb food more effectively. A healthcare provider can help determine the right enzyme dose to meet your digestive needs.

Differentiation from trouble absorbing bile acids: While bile acid malabsorption involves difficulties in absorbing bile acids (important for digesting fats in the intestines), pancreatic enzyme deficiency specifically refers to the lack of digestive enzymes from the pancreas. Both conditions affect digestion but stem from different organs and require distinct treatments.

9. Thyroid disorders

An overactive thyroid (known as hyperthyroidism) can cause the digestive system to work faster than usual. This can lead to more frequent bowel movements, including diarrhea. Other symptoms of hyperthyroidism often include unexpected weight loss, feeling hungrier than usual, and feeling anxious or restless.

Thyroid issues are typically identified by performing blood tests to check hormone levels. Medications to balance these hormone levels can help ease digestive symptoms. If you notice ongoing digestive problems along with other signs of thyroid imbalance, consulting an endocrinologist may be helpful.

10. Diabetes-related complications

When diabetes isn’t managed properly, it can potentially lead to nerve damage in the digestive system. This condition is known as autonomic neuropathy and may cause ongoing digestive issues, including chronic diarrhea or unpredictable bowel movements. Keeping blood sugar levels steady is a key part of managing these symptoms.

For people with diabetes, maintaining tight blood sugar control and checking in with a healthcare provider regularly can help prevent or lessen these complications. Some may also find that certain medications or small dietary adjustments can make a noticeable difference in managing digestive issues related to diabetes.

Read our guides on types of diarrhea and how to treat diarrhea for more.

When you should see a doctor about chronic diarrhea

While some causes of chronic diarrhea can be managed at home, persistent symptoms may require professional attention.

You should see a doctor if:

• Diarrhea lasts more than a few days without showing signs of improvement.
• Symptoms interfere with daily life or cause noticeable weight loss.
• You see a trace of blood in your stool, even a small amount.
• You experience mild but persistent stomach discomfort that doesn’t seem to go away.

You should go to the emergency room if:

• Signs of severe dehydration occur, such as dizziness, rapid heartbeat, or confusion.
• Fever exceeds 103°F (39.4°C) and does not improve with home care.
• Stool contains moderate amounts of blood or appears black and tarry, indicating a possible serious condition.
• You experience sudden, intense abdominal pain that does not subside, suggesting the need for immediate evaluation.

Questions to ask your doctor about chronic diarrhea

Preparing questions for your healthcare provider can help you understand the best ways to manage symptoms and seek appropriate treatment:

• Could certain foods or activities be worsening my symptoms?
• What tests do you recommend to determine the cause of my diarrhea?
• Are there lifestyle changes or dietary adjustments that might help with management?
• What treatment options are available, and are there any potential side effects?

Frequently asked questions: diarrhea causes

If you’re dealing with ongoing diarrhea, you may have questions about what might be causing it and how best to handle it. Here are answers to some common questions.

What if you have had chronic diarrhea for weeks?

Chronic diarrhea lasting several weeks is generally a sign to consult a healthcare provider, as it may indicate an underlying condition. Persistent symptoms may need a more in-depth evaluation to rule out infections, digestive disorders, or other chronic health issues.

What should you consider if you have chronic diarrhea while pregnant?

Pregnant individuals experiencing chronic diarrhea should consult their healthcare provider to rule out infections, food intolerances, or other causes. Staying hydrated is especially important during pregnancy, and a doctor can offer guidance on safe treatments.

Can chronic diarrhea lead to other health conditions?

Yes, having diarrhea for an extended period can lead to other health issues if left untreated. Over time, the body may struggle to take in important nutrients, like B12, iron, and potassium, which it needs for energy and strength. Missing out on these nutrients can lead to symptoms such as feeling extra tired, muscle weakness, and even more serious concerns if it continues.

Managing chronic diarrhea

Chronic diarrhea is often a sign of an underlying health issue, and understanding potential causes can help with effective management. Simple steps like identifying food triggers, managing stress, and working closely with a healthcare provider can support digestive health and improve daily comfort.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Lane Thaut, DO.

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