Understanding Crohn’s disease, ulcerative colitis and IBD

Written by: Professor Ailsa Hart
Published: | Updated: 20/02/2020
Edited by: Alex Furber

Crohn’s disease and ulcerative colitis both come under the category of inflammatory bowel disease, but they are not the same thing. With both of these conditions on the rise worldwide, top gastroenterologist Professor Ailsa Hart explains the difference in support of Crohn’s and Colitis Awareness Week.

Crohn’s disease vs. ulcerative colitis


Crohn’s disease and ulcerative colitis are estimated to affect around 300,000 people in the UK alone. They are the two most common forms of inflammatory bowel diseases (IBD) and can lead to similar symptoms of abdominal pain, diarrhoea, continence issues and fatigue. Sometimes they can lead to symptoms outside of the gastrointestinal tract such as joint pains or sore eyes.


As might you might have guessed, both diseases cause inflammation of the digestive system – but exactly which part depends on the condition.


Crohn’s disease mostly affects the last section of the small intestine (ileum) and the beginning of the large intestine (colon), but it can actually affect any part of the digestive system.


Ulcerative colitis, on the other hand, causes inflammation of the rectum and the colon.


Another distinguishing feature is that whilst ulcerative colitis tends to affect a continuous section of the colon, Crohn’s disease may result in patchy areas of inflammation, leaving normal areas of gut in between.


What’s more, ulcerative colitis usually just affects the lining of the bowel, meanwhile, Crohn’s disease can cause deeper inflammation of the bowel wall.


Smoking and Inflammatory Bowel Disease


There is evidence of a relationship between smoking and IBD. Studies have shown that smokers are at an increased risk of getting Crohn’s disease, though intriguingly, those who smoke are less likely to develop ulcerative colitis.


There is also some evidence to suggest that smokers suffer a milder form of ulcerative colitis – although this is disputed by other studies. The reasons behind this are not well understood and overall it is considered that the negative effects of smoking greatly outweigh the possible benefits.


Signs and symptoms of Crohn’s disease and ulcerative colitis


The main symptoms of Crohn’s disease and ulcerative colitis are very similar and include altered bowel habits, diarrhoea, and faecal urgency or incontinence. This can seriously impact on a sufferer’s quality of life. Other symptoms can also include;


  • Abdominal pain
  • Weight loss
  • Fatigue
  • Joint pain
  • Skin problems
  • Painful eyes
  • Fistulas

On top of this, many people experience a diminished ability to enjoy food. The symptoms of the disease can conspire to seriously impact a person’s daily routine and hamper their ability to achieve their goals.

Treating Inflammatory Bowel Disease


Treatment for Crohn’s disease and ulcerative colitis depends on the severity of the symptoms and how much of the digestive system is affected.


Whether you have Crohn’s disease or ulcerative colitis, a prompt diagnosis and careful monitoring are essential to keep things under control and maximise your quality of life. If you suffer from inflammatory bowel disease, you should visit a specialist who can plan a strategy to manage your condition.  

Professor Ailsa Hart

By Professor Ailsa Hart

Professor Ailsa Hart is an internationally-renowned leading consultant gastroenterologist in London with over 20 years experience. Having trained in medicine at Oxford University, being awarded a First Class Honours Degree, she completed her PhD at Imperial College in London in 2005. She received further clinical training in gastroenterology at the renowned  St Mark's Hospital, Barts Health NHS Trust and University College Hospital, as well as the Academic Medical Centre in Amsterdam.

At the forefront of her field, she is Fellow of the Royal College of Physicians, a member of the British Society of Gastroenterology, particularly contributing to the Clinical Research Group, and on the Governing Board of the European Crohn’s and Colitis Organisation, to name a few. She has been awarded numerous prizes for her outstanding work in medicine.

Prolific in all aspects of gastroenterology, she takes a special clinical interest in inflammatory bowel disease (Crohn's Disease and ulcerative colitis). She works closely with the national charity for inflammatory bowel disease (Crohn's and Colitis UK) and is the UK Lead for Patient and Public Involvement and Engagement in gastroenterology.

She has written two books, publishes extensively in renowned peer-reviewed journals (with over 130 publications) and is Associate Editor of the well-respected journal Alimentary Pharmacology and Therapeutics. She lectures extensively sharing best practice principles around the world and also featured on the BBC documentary “Guts: the strange and mysterious world of the human stomach” on 12th July 2012, presenting research data on faecal transplantation for treatment of inflammatory bowel disease.


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