Difference Between Crohn’s Disease and Ulcerative Colitis

Main Difference –  Crohn’s Disease vs Ulcerative Colitis

Inflammatory bowel disease is defined as a chronic inflammation of all or some parts of the gastrointestinal tract, and Crohn’s disease and ulcerative colitis are the two most common types of it. The common symptoms of these conditions include severe diarrhea, pain, fatigue and weight loss. However, it is important to identify the each condition separately since the outcome can even be life-threatening and method of treatment would highly vary depending on the type, localization of the condition and the severity. The main difference between Crohn’s Disease and Ulcerative Colitis is that ulcerative colitis remains confined to the colon and only affects the topmost layers of it even in the distribution. Crohn’s would affect all three layers of the bowel wall.

This article will describe

1. What is Crohn’s Disease? – Causes, Symptoms, Complications, Diagnosis, and Treatment 

2. What is Ulcerative Colitis? – Causes, Symptoms, Complications, Diagnosis, and Treatment

3. What is the  difference between Crohn’s Disease and Ulcerative Colitis?Difference Between Crohn's Disease and Ulcerative Colitis - Comparison Summary

What is Crohn’s Disease

Defined as a chronic inflammatory condition of the gastrointestinal system, Crohn’s disease mostly occurs in the last part of small intestine (Ileum) and the first part of the colon.  But it can affect any part of the gastrointestinal tract, from the oral canal to anus. The disease can also involve only a few parts of the GI tract while skipping several others.

These inflammatory changes, which are usually confined to the bowel wall, can ultimately lead to narrowing and/or scarring (fibro-stenosis), developing fissures or fistulas and cause bowel obstructions.

Autoimmune conditions, positive family history, and chronic smoking are the commonest risk factors associated with this condition; people of an Eastern European (Ashkenazi) Jewish origin are also known to have a higher incidence.

Patients with Crohn’ disease will usually experience abdominal pain and diarrheas sometimes mixed with blood; these episodes will be as frequent as 10 to 20 times a day. Some individuals will also show a rapid weight loss and mouth sores. Immunosuppressive conditions such as underlying chronic diseases, infections, hormonal changes and smoking can initiate or exacerbate the above symptoms, and some patients might experience symptom-free periods to severe symptomatic phases, depending on the general immunity and severity of the condition.

A proper history of the signs and symptoms, their duration and a thorough abdominal examination will help to get a general idea about the patient’s condition. Barium X-rays of the small intestine and colon, colonoscopy (flexible sigmoidoscopy), intestinal biopsy and stool full report and culture are the main investigative methods used to diagnose having Crohn’s disease. Other routine blood tests and C-reactive protein levels can also be assessed for further evaluation.

The major objective of the treatment is to halt the inflammation in the intestines, to prevent flare-ups and reach a sustainable remission. Few people who are not responding to medication or experience long-lasting symptoms or complications may require a combination of medicines, or surgery. However, all these treatments depend on the severity of inflammation.

Mild symptoms: Anti-diarrheal medicine- Loperamide

Mild-Moderate symptoms: Aminosalicylates, Antibiotics, and anti-inflammatory drugs

Severe symptoms: Corticosteroids, immune-modulators, and biologics. Once the severity is reduced, and disease is under control, a treatment plan to maintain a remission period will be started.

Surgery is indicated if the medicine cannot control symptoms, side effects are severe, long-term use of corticosteroids or severe complications of the disease.

The aim of the surgery is to remove the diseased parts of the colon and to keep the healthy ones. However, in most patients, the disease tends to return because inflammation  has spread to other parts of the bowel as well.   

Main surgeries: bowel resection, strictureplasty and proctocolectomy and ileostomy.

Difference Between Crohn's Disease and Ulcerative Colitis

Schematic of patterns of disease in Crohn’s disease

What is Ulcerative Colitis

Ulcerative colitis is a type of inflammatory bowel disease (IBD) which is characterized by long-term inflammation and ulceration in the gastrointestinal tract which mainly affects the mucosal lining of the large intestine (colon) and rectum.

Ulcerative colitis is graded based on the extent of the inflammation; it could be limited to the rectum with mild symptoms (ulcerative proctitis) or cover most parts of the colon with comparatively severe symptoms.

Causative agents and risk factors include weak or malfunctioning immunity, positive family history, chronic stress and poor dietary nutrients, diseases like Diabetes Mellitus which increases the susceptibility of bowel inflammation  and the use of Isotretinoin, a drug which is used to treat acne. In addition, this condition usually affects women and men who are younger than 30 years of age. But it can arise at any age. There are records of patients who first developed symptoms after the age of 60. Latest research studies also suggest that Ashkenazi Jewish descent individuals are known to be at a high risk of developing ulcerative colitis.

Major symptoms and signs will depend on the affected site and severity of inflammation ; they include passage of loose stools with blood or pus (bloody diarrhea), loss of weight and appetite, cramping abdominal pain usually associated with pain in the rectal area and rectal bleeding, severe need to pass stools, weakness, and mild fever. Symptoms and signs of the condition will gradually progress with time and result in debilitating and long term fatal complications.

A full blood count with blood and stool culture are the routine tests done in suspected patients. Other major modalities of diagnosis include Ultrasound scan, Colonoscopy, Flexible Sigmoidoscopy and CT scan.

Even though there is no permanent cure for ulcerative colitis yet, timely interventions and medical care can help to improve symptoms and signs which will, in turn, improve your quality of life.

Main Difference - Crohn's Disease vs Ulcerative Colitis

Histopathological image of the active stage of ulcerative colitis

Difference Between Crohn’s Disease and Ulcerative Colitis

Crohn’s disease and Ulcerative colitis are two of commonest types of Inflammatory Bowel Disease, which are usually diagnosed by the age of 30 years.


Crohn’s disease mostly occurs in the last part of small intestine (Ileum) and the first part of the colon although it is known to affect any part of the gastrointestinal tract, from the oral canal to anus. The major of the parts affected by ulcerative colitis include the mucosal lining of the large intestine (colon) and rectum.

Ulcerative colitis remains confined to the colon and only affects the topmost layers of it even in the distribution. Crohn’s would affect all three layers of the bowel wall.


Symptoms of Crohn’s mainly include persistent diarrhea sometimes with bleeding, cramping abdominal pain, fever, and fatigue. Ulcerative colitis will result in cramping abdominal pain, loose and bloody stools, bowel incontinence, fatigue, loss of weight and appetite and anemia due to chronic blood loss.

Unlike Ulcerative colitis, Crohn’s has extraintestinal manifestations as well, with the involvement of skin, eyes, joints, and liver.


Main complications of Crohn’s disease include blockages of the intestine due to inflammatory scarring, ulceration (sores) in the intestinal tract and fistulas and it is also known to increase the risk of colon cancer.

Untreated Ulcerative colitis can give rise to the formation of holes in the colon, liver disease, osteoporosis and blood clots.


Periods of remission often tend to be longer with Ulcerative colitis than with Crohn’s disease with less frequent complications.


With the exception of biologic therapy, modes of interventions for both the conditions remain the same but more importantly, most patients with Ulcerative colitis will almost never require surgery.

Image Courtesy:

“Patterns of Crohn’s Disease” By Samir, vectorized by Fvasconcellos – w:Image:Patterns of CD.jpg (CC BY-SA 3.0) via Commons Wikimedia 

“Ulcerative colitis (2) active” By User:KGH (CC BY-SA 3.0) via Commons Wikimedia 

About the Author: Embogama

Embogama is a passionate freelance writer for several years. Her areas of interest include general medicine, clinical medicine, health and fitness, Ayurveda medicine, psychology, counseling and piano music