What is Crohn’s disease?

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Crohn’s disease is a chronic illness that differs from ulcerative colitis because it can affect any section of the digestive tract with inflammation occurring in all layers of the intestinal wall. It may affect discontinuous areas, i.e., the digestive tract contains alternating sections of healthy areas and inflamed segments.

As inflammation affects the entire intestinal wall, Crohn’s disease can course with complications such as stenosis (narrowing of the intestinal lumen) and/or fistulas (a connection between two intestinal loops or to an organ, e.g., the urinary bladder) which may be accompanied by collections of pus.

The most frequently affected areas are:

  • Ileum: predominantly the distal ileum
  • Colon: any segment
  • Ileum and colon: both
  • Upper digestive tract: from the mouth to the proximal ileum

Síntomas más frecuentes de la Enfermedad de Crohn

Standing person with abdominal pain

Dolor abdominal

Person standing with diarrhoea cramps


Physical examination of an abdominal mass

Abdominal pain

Person vomiting in a toilet

Nausea and/or vomiting

Scale with a down arrow indicating a weight loss

Weight loss

Thermometer with a danger signal indicating fever

Fever (a sign of the condition’s severity)

Symptoms may vary depending on the disease’s location. When it affects the small intestine, patients primarily experience abdominal pain, diarrhoea, weight loss and/or loss of appetite. If the disease affects the colon, then the predominant symptom is diarrhoea with or without blood.

Substantiated information by:

Ingrid Ordas Jimenez
Marta Gallego Barrero

Published: 20 February 2018
Updated: 4 September 2020

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