What Causes Chronic Diarrhea in Adults?

Chronic diarrhea in adults has multiple potential causes, from infections to chronic diseases. Irritable bowel syndrome can cause chronic diarrhea and abdominal pain, although some people have constipation or alternating bowel habits. Inflammatory bowel diseases like Crohn's disease and ulcerative colitis create persistent inflammation leading to frequent loose stools. Food intolerances can trigger digestive symptoms. Many adults have difficulty digesting lactose, but not everyone develops symptoms. Some medications, including certain antibiotics, magnesium-containing antacids, and some blood pressure medicines, can cause diarrhea as a side effect. Some parasitic or bacterial infections can cause prolonged diarrhea. Viral diarrhea is usually short-lived but may last longer in some people. Other causes include celiac disease, hyperthyroidism, diabetes complications, and malabsorption disorders. Consult a healthcare provider if diarrhea lasts more than four weeks. Seek care sooner for blood or black stools, severe pain, high fever, significant weight loss, signs of dehydration, or difficulty keeping fluids down.