Crohn’s Disease – Diagnosis, Symptoms, and Treatment

Doctor Nathan LeDeaux, MD

Medically reviewed by Dr. Nathan LeDeaux, MD

Medical Professional

Updated - December 22, 2020

Nathan LeDeaux is an emergency medicine physician at the University of Wisconsin and got his M.D. from Northwestern University in Chicago Illinois.

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What is Crohn's Disease?

Inflammatory bowel disease (IBD) is a medical condition characterized by autoimmune injury and inflammation of the gastrointestinal tract, which includes the esophagus, stomach, intestines, and the rectum.  This disorder is categorized into 2 main subtypes: Crohn’s disease and Ulcerative Colitis.  These two conditions have significant overlap but also have unique features and treatments.  Crohn’s disease may affect any portion of the gastrointestinal tract from the mouth down to the anus.  In contrast, ulcerative colitis typically only affects the large bowel, commonly called the colon.

Patients with either Crohn's disease or ulcerative colitis often experience episodic abdominal pain, bloating, nausea/vomiting, diarrhea, bloody stool, and mucus in the stool.  Patients may also develop low grade fever and malaise – potential long term complications include nutritional deficiencies, fistula formation, and colon cancer.

What Causes Crohn's Disease?

Inflammatory bowel disease is likely caused by both genetic and environmental factors.  Crohn’s disease and ulcerative colitis are forms of autoimmune inflammatory disease in which the immune system inappropriately attacks normal body tissue and organs – such as the gastrointestinal tract.

Inflammation in the gastrointestinal tract of patients with Crohn’s disease may cause several other conditions, the most common are:

  • Oral ulcers
  • Small intestinal inflammation
  • Inflammation of the large intestine – colitis
  • Proctitis – rectal inflammation
  • Anal fissures

Patients with ulcerative colitis or Crohn’s disease that is affecting the colon typically have abdominal pain, bloating, and bloody diarrhea due to inflammation, mucosal ulceration, and bleeding in the large intestine.  Long-term or intermittent inflammation involving the terminal ileum – as is frequently seen in Crohn’s disease –may result in the development of fat malabsorption and nutritional deficiencies (especially vitamins A, D, E, and K). 

How Common is Crohn's Disease?

Inflammatory bowel disease is relatively common in the United States, the Crohn’s disease subtype is present in about 201 out of 100,000 people. Ulcerative Colitis is slightly more common with 238 per 100,000 people in the United States reportedly living with the disease. 

There are many more common conditions that may have some of the symptoms of Corhn’s disease. The most common of these is irritable bowel syndrome, this condition is extremely common but is unrelated to either of the inflammatory bowel diseases and does not share any of the complications of these diseases. 

Signs and Symptoms

The signs and symptoms of inflammatory bowel disease often begin with mild and generic symptoms that result in general discomfort, intolerance of foods, and malaise. These symptoms may then become more specific, with the symptoms that define Crohn’s disease and ulcerative colitis arising. The most common symptoms that are seen in these conditions are as follows:

  • Painful oral ulcers
  • Abdominal pain
  • Bloating
  • Nausea & vomiting
  • Diarrhea
  • Bloody stool
  • Stool with mucus

Patients may also present with malaise and low grade fever.  Episodes may be intermittent lasting days to weeks if left untreated.  Severe cases of gastrointestinal inflammation can result in exquisite abdominal pain, vomiting, and the inability to tolerate anything by mouth.  These cases require hospitalization with intravenous fluids, pain management, and corticosteroids.

A subset of patients will develop toxic megacolon with death of intestinal tissue requiring surgical debridement – patients with this type of presentation are generally very ill and have a history of severe ulcerative colitis or Crohn’s disease.


The diagnosis of Crohn's disease of Ulcerative colitis is generally suspected by the presence of the symptoms above. Most specifically the presence of rectal bleeding and recurrent episodes of nausea, vomiting, and diarrhea. The physical exam may reveal sores in the mouth or near the anus that suggest the diagnosis of Crohn’s disease but the definitive diagnosis is made using endoscopy and colonoscopy

During upper endoscopy, your doctor will visualize the upper gastrointestinal tract by providing you with sedation and advancing a camera down the mouth into the esophagus. They will continue to advance the scope, evaluating for any ulcers or inflammatory lesions, all the way past the stomach and into the small intestine.  During colonoscopy, a similar procedure is performed but your doctor will enter the rectum and advance a scope through the colon.

Sometimes, you doctor may recommend a radiographic study in which they have you swallow contrast that highlights the intestines and then perform a CT scan or MRI – this test is obtained in order to evaluate the middle portions of the bowel that cannot be visualized with upper and lower endoscopy. These scans may also be ordered if your doctor suspects the intestines may have been damaged enough to result in the formation of a fistula, an abnormal connection between different sections of the intestines. 

Other commonly ordered blood tests include a CMP (comprehensive metabolic panel), CBC (complete blood cell count), and coagulation studies (PT/INR, PTT).  Your doctor will usually check your stool for Clostridium difficile toxin prior to performing colonoscopy in order to rule out C. difficile colitis – this is an infectious form of colitis that can mimic or coexist with inflammatory bowel disease.

Crohn's Disease Medication and Treatment

Infectious colitis must first be excluded as an etiology of symptoms during acute flares of inflammatory bowel disease – this frequency involves ruling out C. difficile infection through a stool test.  Patients are then typically treated with short-term oral or intravenous corticosteroids which may include Orapred (prednisone) or Solumedrol (methylprednisolone), respectively.

Patients with mild ulcerative colitis can benefit from oral mesalamine, which is available as Pentasa, Asacol, or Canasa. These medications reduce the amount of inflammation within the intestines by reducing the immune system's production of inflammatory molecules.

Individuals with limited ulcerative proctitis, inflammation of only the rectum, are often prescribed mesalamine rectal suppositories.  Occasionally they will require use of Rowasa (mesalamine enemas)Cortenema and Colocort (corticosteroid enemas) may also be beneficial in some patients. The exact regimen used varies from patient to patient based on how they respond to these medications.

In more severe or recurrent cases of inflammatory bowel disease, you doctor may recommend long term treatment with Imuran (azathioprine).  Occasionally, they will prescribe Neoral (cyclosporine) or Entyvio(vedolizumab). These medications have more serious side effects and require administration through regular IV infusions. This makes them a last resort option for controlling severe inflammatory bowel disease. 


  1. Silverberg MS, Satsangi J, Ahmad T, et al. Toward an integrated clinical, molecular and serological classification of inflammatory bowel disease: report of a Working Party of the 2005 Montreal World Congress of Gastroenterology. Can J Gastroenterol 2005; 19 Suppl A:5A. -
  2. Satsangi J, Silverberg MS, Vermeire S, Colombel JF. The Montreal classification of inflammatory bowel disease: controversies, consensus, and implications. Gut 2006; 55:749. -
  3. Kornbluth A, Sachar DB, Practice Parameters Committee of the American College of Gastroenterology. Ulcerative colitis practice guidelines in adults: American College of Gastroenterology, Practice Parameters Committee. Am J Gastroenterol 2010; 105:501. -
  4. Lichtenstein GR, Hanauer SB, Sandborn WJ, Practice Parameters Committee of American College of Gastroenterology. Management of Crohn’s disease in adults. Am J Gastroenterol 2009; 104:465. -


Crohn’s Disease Medications

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.