Inflammatory bowel disease (IBD) involves chronic inflammation of all or part of the digestive tract. IBD primarily includes colitis and Crohn’s disease. IBD can be debilitating and sometimes leads to life-threatening complications.

Ulcerative colitis is an IBD that causes long-lasting inflammation and sores (ulcers) in the innermost lining of the large intestine (colon) and rectum.

Crohn’s disease is an IBD that causes inflammation of the lining of the digestive tract. Inflammation often spreads deep into affected tissues and can involve different areas of the digestive tract such as the large and small intestine.

Collagenous colitis and lymphocytic colitis are also IBDs but are considered separate from classic IBD.



Common symptoms of ulcerative colitis and Crohn’s disease include:


  • Diarrhea
  • Fever and fatigue
  • Abdominal pain and cramping
  • Blood in the stool
  • Reduced appetite
  • Unintended weight loss


Types of ulcerative colitis according to location of inflammation and severity of symptoms:


  • Ulcerative proctitis: Confined to the area closest to the anus and rectum with rectal bleeding as the only symptom.
  • Proctosigmoiditis: Inflammation of the rectum and sigmoid colon (lower end of the colon) with symptoms such as bloody diarrhea, abdominal cramps and pain and inability to move bowels.
  • Left-sided colitis: Inflammation extends from the rectum up through the sigmoid and descending colon. Symptoms include bloody diarrhea, abdominal pain and cramping on the left side and unintended weight loss.
  • Pancolitis: Inflammation that affects the entire colon and causes severe bloody diarrhea, abdominal pain and cramps, fatigue and significant weight loss.
  • Acute severe ulcerative colitis: Inflammation that affects the entire colon and causes severe pain, profuse diarrhea, bleeding, fever and inability to eat.


Crohn’s disease involves inflammation that most commonly affects the last part of the small intestine (ileum) and the colon. Inflammation may cause narrowing of the bowel wall or a tunnel through the bowel wall.



The exact cause of inflammatory bowel disease is unclear. However, a possible cause is an immune system malfunction. An abnormal immune response can cause the immune system to attack cells in the digestive tract. Some cases of IBD are associated with family history of the disease.


Risk factors

Risk factors for inflammatory bowel disease include:


  • Age (most cases of IBD are diagnosed before the age of 30)
  • Being white
  • Family history
  • Smoking
  • Isotretinoin use (medication to treat scarring cystic acne or acne)
  • Nonsteroidal anti-inflammatory medications
  • Environmental factors (living in northern climates, an urban area or in an industrialized country as well as a diet high in fat or refined foods)



Crohn’s disease may cause the following complications:


  • Inflammation
  • Bowel obstruction
  • Ulcers in the digestive tract
  • Fistulas
  • Anal fissure
  • Malnutrition
  • Colon cancer
  • Other health problems such as inflammation of the eyes, skin or joints; anemia; osteoporosis, inflammation of the liver or bile ducts and delayed growth or sexual development in children.
  • Certain medications for Crohn’s disease such as corticosteroids


Ulcerative colitis may cause the following complications:


  • Severe bleeding
  • A hole in the colon (perforated colon)
  • Severe dehydration
  • Liver disease (rare)
  • Bone loss (osteoporosis)
  • Inflammation of the skin, eyes and joints
  • Sores in the lining of the mouth
  • Increased risk of colon cancer
  • Rapidly swelling colon (toxic megacolon)
  • Increased risk of blood clots in veins and arteries