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Inflammatory Bowel Disease: Symptoms and Risk Factors

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn's disease, are chronic inflammatory disorders of the digestive tract. They are among the most common digestive ailments, affecting more than 1 million Americans.

The causes of IBD have not been fully established, but the disorder is believed to be associated with abnormal activation of the immune system.

Affected individuals, especially those with ulcerative colitis, have a higher risk of colon cancer. In addition, they have an increased risk for hepatitis, cirrhosis, arthritis, and nutritional deficiencies.


Crohn's disease and ulcerative colitis have many common symptoms, which may develop rapidly or gradually. These include:

  • Persistent diarrhea, which may be bloody and lead to dehydration.
  • Abdominal pain.
  • Loss of appetite and subsequent weight loss: Children with IBD often fail to develop and grow properly.
  • Fever, which is common in severe cases.
  • Extraintestinal manifestations, such as arthritis (more common in Crohn's disease); eye inflammation; skin disorders (more common in Crohn's disease); anemia; and liver disorders.

Risk Factors

  • Genetics: Specific gene mutations occur in 30 percent of patients with Crohn's disease.
  • Environment: IBD is more common in developed countries, urban areas, and colder climates, and among people with high socioeconomic status. Recently, Crohn's disease has become as frequent in Japan as in the United States, likely due to westernized lifestyle, including diet habits, increasing urbanization, and industrialization.
  • Age: Onset is usually between the ages of 15 and 35.
  • Race: Whites have the highest risk. Also, Ashkenazi Jews have up to an eight times greater risk of developing IBD, compared with the general population.
  • Family history: People with an affected relative have a 10-fold greater risk of having IBD. If the relative is first-degree, the risk is 20 to 35 times greater.
  • NSAIDs: Use of nonsteroidal anti-inflammatory drugs, such as ibuprofen, may trigger or cause relapse of IBD.
  • Smoking: Studies on smoking and IBD risk, including those focusing on maternal smoking during pregnancy and risk to the child of future IBD, have shown conflicting results.
  • Lack of breast-feeding: Some evidence has suggested that breast-feeding may reduce the risk, but more studies are needed to assess this possibility. (See Nutritional Considerations.)


Inflammatory Bowel Disease: Diagnosis and Treatment >>