Chronic diarrhea—what if your gut is inflamed, not “sensitive”?

Chronic diarrhea (loose or watery stools lasting four weeks or more) affects up to 5 percent of adults at any given time. It’s often blamed on “irritable bowel syndrome” (IBS), a disorder of gut sensitivity. But sometimes ongoing diarrhea is a sign of true inflammation in the digestive tract—think inflammatory bowel disease (IBD), microscopic colitis or bile acid malabsorption—rather than just a “sensitive gut.” Here’s how to tell the difference, what tests to consider and how to work with your doctor to get relief.

Why distinguishing inflammation from sensitivity matters

• IBS (diarrhea-predominant type) is driven by altered gut-brain signals, pain sensitivity and motility changes. Inflammation and tissue damage are minimal or absent.
• IBD (Crohn’s disease, ulcerative colitis) causes immune-mediated inflammation, sometimes with ulcers or bleeding. If untreated, it can lead to strictures, fistulas and nutritional deficiencies.
• Microscopic colitis (lymphocytic, collagenous) shows up on biopsy but may look normal on colonoscopy. It’s an inflammatory condition that causes chronic watery diarrhea, often in older adults.
• Bile acid malabsorption occurs when bile acids spill into the colon, irritating the lining and speeding up transit. It can follow gallbladder removal or arise without clear cause.

Getting the right diagnosis helps you:

• Avoid unnecessary or ineffective treatments
• Prevent complications (for example, strictures in Crohn’s disease)
• Tailor diet, medications and lifestyle changes to the underlying cause

Warning signs that point toward inflammation

If you have chronic diarrhea plus any of these red flags, talk to your doctor about getting tests for inflammation:

• Blood in stool or black, tarry stools
• Unexplained weight loss (more than 5 percent of body weight in a few months)
• Fever or joint pain
• Severe fatigue or night sweats
• Iron deficiency anemia (low hemoglobin on routine labs)
• Family history of IBD, celiac disease or colon cancer
• Onset of symptoms after age 50

Key non-invasive tests for gut inflammation

Before jumping to invasive procedures, your doctor may order stool and blood tests. Heida et al. (2013) highlight the value of fecal biomarkers:

• Fecal calprotectin
– A protein released by white blood cells during inflammation.
– Levels < 50 µg/g stool suggest low likelihood of IBD.
– Levels > 150 µg/g stool raise concern for moderate to severe inflammation.

• Fecal lactoferrin
– Another marker of neutrophil activity in the gut.
– Elevated levels point to active inflammation.

• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
– General markers of systemic inflammation.
– May be normal in mild colonic disease, so not solely relied upon.

• Serologic tests (for celiac disease)
– Tissue transglutaminase antibodies (tTG-IgA)
– Total IgA level (to rule out IgA deficiency)

If inflammation markers are high, your doctor will likely recommend a colonoscopy with biopsies to:

• Confirm IBD vs microscopic colitis
• Assess extent and severity of disease
• Rule out other causes (polyps, malignancy)

Advanced imaging and liver checks

Chronic diarrhea may also coexist with or result from liver disease. Two key resources:

• Elastography (Tsochatzis et al., 2011)
– A painless ultrasound-based test that measures liver stiffness.
– Helps stage fibrosis in chronic liver diseases (hepatitis, non-alcoholic fatty liver disease).
– Advanced fibrosis can alter bile acid metabolism, contributing to diarrhea.

• Natural history of cirrhosis (D’Amico et al., 2006)
– Cirrhosis can impair bile acid reabsorption, leading to bile acid diarrhea.
– Patients with decompensated cirrhosis may have malabsorption of fats, vitamins A, D, E, K.

If you have known liver disease or abnormal liver tests (AST, ALT, ALP, bilirubin), mention this to your gastroenterologist. Elastography may be part of a comprehensive evaluation.

Treatment approaches for inflammatory causes

Once true inflammation is confirmed, treatment focuses on reducing immune activation, promoting healing and restoring nutritional balance.

Medication options
• 5-ASA agents (mesalamine, sulfasalazine)
– First-line for mild to moderate ulcerative colitis.
• Corticosteroids (prednisone, budesonide)
– Used short-term for flares; not for maintenance.
• Immunomodulators (azathioprine, 6-mercaptopurine)
– Maintains remission in moderate to severe IBD.
• Biologics (infliximab, adalimumab, vedolizumab)
– Target specific immune pathways; used in refractory cases.
• Bile acid binders (cholestyramine, colesevelam)
– For bile acid diarrhea; they trap excess bile in the gut.

Diet and lifestyle
• Low-residue, low-fiber during flares
• Lactose avoidance if lactase deficient
• Small, frequent meals to reduce gut load
• Probiotics (some benefit in ulcerative colitis)
• Adequate hydration and electrolyte replacement

Nutritional supplementation
• Iron, vitamin B12, vitamin D, calcium, folate as needed
• Consult a dietitian for personalized meal planning

Monitoring and follow-up

• Repeat fecal calprotectin to gauge treatment response
• Regular colonoscopy intervals (per guidelines) to monitor healing
• Liver function tests and elastography if there’s underlying liver involvement
• Bone density scans if long-term steroids are used

When to seek urgent care

Call your doctor or go to the emergency department if you experience:

• Severe abdominal pain
• High fever (> 101 °F or 38.3 °C)
• Signs of dehydration (dizziness, lightheadedness, very little urine)
• Blood loss requiring urgent attention
• Severe weakness or fainting

Take charge of your symptoms

If you’re still wondering whether your chronic diarrhea is just IBS or true inflammation, consider using a free, online “symptom check for” chronic diarrhea to help organize your concerns. This can guide you on which questions to ask your doctor and what tests you might need.

Remember, chronic diarrhea isn’t something you must endure without answers. An inflamed gut needs a different workup and treatment plan than a “sensitive” gut. With the right tests—fecal biomarkers, colonoscopy, liver imaging—and a clear treatment strategy, you can get back to life without constant trips to the bathroom.

Speak to a doctor about anything that feels life threatening or seriously concerning. Your health matters—don’t wait to get the right diagnosis and care.