Cart 0

Crohn’s Disease - Part 1

Posted by Eamonn Brady on


Crohn’s disease is one of the two main forms of inflammatory bowel disease (IBD). The second main form of inflammatory bowel disease is ulcerative colitis. Crohn’s disease causes inflammation (irritation, redness, swelling and pain) of the digestive system.

Crohn’s is a chronic condition meaning it is persistent and long lasting with many experiencing it as an ongoing and life-long condition often with periods of remission (period when person is well) as well as periods of relapses or flare-ups. The exact cause is unknown; it is thought to be due to an immune response to perhaps the likes of bacteria or stress. There is currently no cure for Crohn’s but medication and sometimes surgery can give long periods of relief.

Difference between Ulcerative colitis and Crohn’s Disease

Ulcerative colitis only affects the inner lining of the colon, also known as the large intestine. In Crohn's disease, inflammation can appear anywhere in the digestive tract, from the mouth to the anus. Crohn’s generally affects all the layers of the bowel walls, not just the inner lining so tends to have more serious symptoms.

How does Crohn’s disease affect the intestinal tract?

The most common area is the last part of the small intestine (terminal ileum) and the first part of the large intestine (colon), near the appendix. For some only the colon is affected, in a pattern like ulcerative colitis. In others, multiple parts of the intestinal tract are affected. Rarely, the mouth, throat, oesophagus or stomach may be affected. A patch of inflammation may be as small as a few centimetres or extend most of distance along the intestinal tract. As well as affecting the lining of the bowel, Crohn’s may also go deeper into the bowel wall.


Crohn’s disease ranges from very few symptoms to frequent flare-ups or constant disease. The most common symptoms during a flare-up are:

  • Abdominal pain and diarrhoea. Sometimes mucus, pus or blood is mixed with the diarrhoea.
  • Tiredness and fatigue. This can be due to the illness itself, from the weight loss associated with flare-ups or surgery, anaemia from blood loss or simply due to a lack of sleep resulting from symptoms likes pain and diarrhoea
  • Feeling generally unwell. Some people may have a raised temperature and feel feverish.
  • Mouth ulcers
  • Loss of appetite and weight loss.
  • Anaemia (a reduced level of red blood cells). Crohn’s makes anaemia more likely due to blood loss, not eating enough because of symptoms like pain and diarrhoea and because the body is not fully absorbing the nutrients from the food.


How common is Crohn’s?

Crohn’s disease affects about one in every 650 people. Crohn’s appears to be slightly more common in women than in men. The incidence of Crohn's disease is higher than ulcerative colitis in children. The peak age of incidence of Crohn’s is between the ages of 15 and 35. It is more common in smokers.

Main types of Crohn’s disease

Crohn’s is often categorised to which part of the intestinal tract is most affected. The main types are:


Terminal ileal and ileocaecal

Crohn’s in the ileum (the last part of the small intestine) is known as ileal or sometimes ‘terminal ileal’ Crohn’s because it affects the terminus or end of the ileum. If it affects the beginning of the large bowel it is known as ileocaecal Crohn’s in which pain is often experienced in the lower right side of the abdomen, especially after eating. There is often weight loss and diarrhoea. Because Crohn’s in the ileum can make it difficult for the body to absorb bile salts, bile salts can build up leading to irritation the bowel lining; Diarrhoea often occurs and is most likely to be watery. The diarrhoea is unlikely to be bloody, as any blood lost will be digested by the time it reaches the rectum. About four in 10 people with Crohn’s have ileal or ileocaecal disease.

Small bowel

Abdominal pain and diarrhoea are also common symptoms if Crohn’s occurs further up the small bowel. Again, the diarrhoea is unlikely to be blood stained, but weight loss and anaemia may be experienced. Nearly a third of people with Crohn’s have it in the small bowel.


Crohn’s disease in the colon (large intestine or large bowel) is known as ‘Crohn’s colitis’. This is a common form of Crohn’s disease. The main symptom tends to be blood stained diarrhoea. Because of the inflammation, the colon cannot hold as much waste as normal so very frequent bowel movements occur (six or more a day), especially if the rectum is inflamed.


Crohn’s in the upper intestinal tract (the oesophagus, stomach or duodenum) is much less common. Symptoms that indicate Crohn’s in the upper intestinal tract include indigestion-like pain, nausea, loss of appetite, and weight loss.


Crohn’s in the area around the anus can occur on its own or at the same time as inflammation in other parts of the body. Symptoms include:

  • Fissures: tears in the lining of the anal canal which can cause pain and bleeding, especially during bowel movements.
  • Skin tags: small fleshy growths around the anus.
  • Haemorrhoids: swollen areas in the anal canal.
  • Abscesses: collections of pus that can become swollen and painful. Mainly occur around the anus and can cause a fever or lead to a fistula.
  • Fistulas: narrow tunnels or passageways between the intestinal tract and the skin or another organ. Discussed in more detail later.


Oral Crohn’s

Crohn’s can occasionally affect the mouth. True oral Crohn’s which typically causes swollen lips and mouth fissures, is rare. However, about one in five people with Crohn’s tend to develop mouth ulcers.

To be continued…next week


Disclaimer: Please ensure you consult with your healthcare professional before making any changes recommended

For comprehensive and free health advice and information call in to Whelehans, log on to or dial 04493 34591 (Pearse St) or 04493 10266 (Clonmore).

Share this post

← Older Post Newer Post →