IBS vs. IBD: what's the difference?

Written by: Dr Aathavan Loganayagam
Published: | Updated: 21/01/2019
Edited by: Laura Burgess

What is the difference between IBS and IBD?

To put it simply, irritable bowel syndrome (IBS) is when your digestive system has something functionally wrong without a serious underlying disease causing the abdominal symptoms. Irritable bowel syndrome is commonly caused by certain foods, emotional stress, and sometimes medications. It is thought that it is due to increased spasms within the intestinal wall but we do not know the exact causes yet. Importantly, when we investigate irritable bowel syndrome, we do not find any serious abnormalities. Irritable bowel syndrome does not progress to anything serious such as bowel cancer.

Inflammatory bowel disease (IBD) is completely opposite where you have a structural abnormality of the bowel due to an inflammation, which can cause progressive damage and serious complications. The exact cause of IBD is not known but studies suggest a combination of genes and problems with the immune system as factors. If left untreated, patients are unwell with significant symptoms. If inflammatory bowel disease is ignored it can lead to serious conditions such as bowel cancer or arthritis.


Can IBD cause weight gain?

A common misconception amongst the general public is that inflammatory bowel disease always causes weight loss. Weight loss can occur when the disease is active, there is ongoing inflammation and the patient is unable to eat adequately and absorb nutrients. The patient may also lose their appetite and in this scenario, can lose weight. Some patients suffer from a mild strain of the disease and are generally well enough to adequately maintain their weight.


However, this is not the case across the board. When patients are on steroid treatment and are unable to exercise as a result of the condition, they may gain weight. Weight loss or gain when experiencing IBD really depends on the individual. 

If you are concerned that you have either IBS or IBD, book to see a specialist

By Dr Aathavan Loganayagam

Dr Aathavan Loganayagam is a leading London gastroenterologist who trained in medicine at Guy’s, King's and St Thomas’ medical schools. He underwent rigorous structured specialty training in gastroenterology and general internal medicine in the well respected South London training programme.

Dr Loganayagam spent two years during postgraduate training as a research and endoscopy fellow at Guy’s and St Thomas’ Hospitals, London. His research was in the fields of pharmacogenetics, inflammatory bowel disease and gastrointestinal malignancy.

He has received many awards and grants for outstanding research work, including the prestigious NHS Innovation London Award. Dr Loganayagam has numerous publications in peer-reviewed journals on all aspects of gastroenterology. He is actively involved in clinical research.

Currently, Dr Loganayagam is the lead clinician for inflammatory bowel disease and nutrition at Queen Elizabeth Hospital, Woolwich. Diagnostic and advanced therapeutic endoscopy remains a major part of his clinical expertise, including assessment and treatment of inflammatory bowel disease, strictures, polyps and cancers.

Dr Loganayagam is an approachable doctor who takes pride in his communication skills with patients and he is keen to ensure that patients are fully informed and involved in all aspects of their care.

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