Symptoms of Crohn's Disease present themselves in a myriad of ways.  The most common symptom is abdominal pain, typically a sufferer will complain of pains in the left portion of their abdomen.  Diarrhea, sometimes bloody - characterized by black stool, is also a frequent symptom.  Do not confuse blood in the stool with common causes of black stool, such as Pepto-Bismol_®.  Vomiting may occur, and weight loss is typical in sufferers due to a decreased ability to absorb nutrients in an inflamed digestive tract.  Sufferers may often have a quick digestive system in which contents pass from the mouth to anus much faster than healthy individuals.

Non-digestive tract symptoms that may occur include arthritis, lethargy, inability to focus, inflammation of the eye, and skin rashes.

As the disease progresses in severity or over time, strictures may occur in which the bowels passageways narrow due to constant inflammation, fistulas - new passages that form between different parts of the body and the digestive tract, and impaction in which the digestive tract becomes blocked by feces.  Crohn's patients are also at an increased risk of colon cancer.