Diarrhea can be caused by many conditions such as: gastro-intestinal infections, alimentary intoxications, bad-absorption syndromes, autoimmune diseases (Crohn’s disease, colitis ulcerative, etc.), irritable bowel syndrome, etc. You can visit your GP (general practitioner). A physical examination, blood/urine analyses (standard plus bilirubin, urobilinogen, AST, ALT, alkal phosphatasis) and microbiological examination of the feces for bacteria, viruses and parasites can help diagnose the condition. Further examinations include an abdominal ultrasound and colonoscopy, if necessary.