What Is Inflammatory Bowel Disease?


Inflammatory Bowel Disease (IBD) is a term that describes 2 conditions that affect the gastrointestinal tract causing chronic inflammation. It happens when the immune system does not work effectively when it comes into contact with harmless viruses, bacteria, or food within the gut.1, 2 It can occur in individuals of any age, and often requires a variety of treatments. 

The two  conditions that make up IBD are Crohn's disease and ulcerative colitis. Both conditions have similar symptoms and are both life-long. However, there are differences between the two. For example:

  • Ulcerative colitis (UC) affects the lower part of the gastrointestinal tract (GI). This includes the colon and rectum. The colon refers to the bowel, and the rectum is the end section of the bowel where poo is stored. 
  • Crohn’s Disease (CD) affects any part of the gastrointestinal tract. This may include any part from the mouth to the bottom (anus). Inflammation is mostly patchy. This means there may be areas of the GI that  are not inflamed and otherwise healthy.3

With both types of IBD, there may be times of remission. Remission refers to the period of time  when there are no symptoms present. Time of remission may last for days, weeks, or even years. Additionally, IBD can occur in individuals of any age, although there is a higher diagnosis rate for those aged 14 to 50 years

There is a lot to know about IBD including the causes, symptoms, and treatment. However, do not feel overwhelmed because this article will explain everything you need to know about IBD in simple terms.  

Causes of inflammatory bowel disease

The exact causes of IBD are still unknown. However, it is thought that many factors may influence the risk of developing IBD. These can be divided into hereditary (genetics) and immune responses to environmental triggers. 

Genetics may determine the risk for developing IBD:

  • Individuals who have a close relative with the disease have a higher risk of IBD, this is particularly seen within identical twins4
  • Certain ethnicities, particularly Ashkenazi Jews, have higher rates of IBD than other ethnic groups5

The immune system may not be able to respond effectively to environmental triggers such as:

  • Smoking can increase the risk for CD but act as a protective factor for UC6
  • The intake of oral contraceptives may increase the risk for both types of IBD 7,8 
  • However, there is still little evidence to suggest a causative relationship between oral contraceptive intake and diagnosis of IBD
  • Traditionally, IBD has affected those who work indoors and have a high socio-economic status9 Although there have been multiple theories used to explain this, the most plausible theory points to the amount of sedentary behaviour resulting in slow gastric emptying time. This would mean food toxins are in contact with the gut wall for a longer time which leads to inflammation9

With all this being said, experts are still researching all the factors that can cause IBD and there is no way of preventing IBD. Furthermore, many factors may influence the development of IBD but not necessarily cause the disease.

Signs and symptoms of inflammatory bowel disease

The symptoms of IBD may be different for everybody. There may also be periods where you feel fine without any symptoms. There may also be other times when there is a sudden onset of severe symptoms due to a high level of inflammation, also known as flare-ups. About half of all IBD patients have one flare-up per year within the United Kingdom. Therefore it is important to address the signs and symptoms of IBD so flare-ups can be effectively managed.

Symptoms of IBD may include:10

  • Bloody stools
  • Weight loss
  • Extreme fatigue
  • Abdominal pain 

Other symptoms which are more common for individuals with CD are:11

  • Joint pain
  • Sore eyes
  • Mouth ulcers
  • High temperature
  • Feeling or being sick

Additionally, common symptoms for those with UC are:12

  • needing to poo frequently
  • recurring diarrhea

Similar symptoms may be experienced with people who have Irritable Bowel Syndrome (IBS), a syndrome that does not cause inflammation and rarely requires hospitalisation. IBS refers to a group of symptoms like constipation, bloating, and stomach pain rather than a disease itself. However, whether you are experiencing symptoms of  irritable bowel syndrome or inflammatory bowel disease, it is always best to see your healthcare professional to get it checked out. 

Once you see a doctor they can identify the cause of your symptoms and perform a variety of tests to diagnose IBD. To begin with, your doctor is most likely to take blood tests and stool tests. These can identify problems like anemia and inflammation. An endoscopic procedure is the most common diagnostic tool after the initial blood tests have been performed. An endoscopic procedure is when a small camera is attached to the end of a lighted tube and is inserted into the GI tract to look for inflammation. Many different types of endoscopic procedures can be used to test for IBD, they all look at different parts of the digestive system but rely on the same method of inserting a camera.

Alongside blood tests and endoscopic procedures, there may be other methods for testing for IBD including:13

  • Biopsies, where a small tissue is removed from the inside of the intestine
  • Radiology scans and diagnostic imaging may include X-rays and CT scans
  • Prognostic testing- a relatively new concept that  is not widely available. This type of testing is used to predict the progression of IBD. It can help identify patients who may require invasive treatment earlier on or the response of certain medications on a patient

Management and treatment for inflammatory bowel disease

IBD is a lifelong disease, which means it cannot be cured. However, there are lots of ways to manage IBD and its symptoms so that you can live comfortably. Once you are diagnosed with IBD, you should be given relevant information about your diagnosis and treatment applicable to your symptoms and diagnosis. 

These treatments may include medicines to help with:14

  • Protecting the immune system. These medicines are known as immunomodulators
  • Decreasing the amount of inflammation within the gut. These may be short-term medicines like steroids, these help reduce the amount of inflammation during flare-ups
  • Treating symptoms associated with IBD e.g., antidiarrheals for diarrhea

Other treatments may be in the form of invasive treatments or educational advice. For example:15, 16

  • Information may be given about surgery to remove sections of the gut if required. Surgery can only be performed with consent from the patient. Different types of surgery will be carried out dependent on which type of IBD is present
  • Surgery for CD involves removing the diseased bowel and connecting the two ends of the healthy bowel together. After surgery, the body adapts and functions as it did before
  • Surgery for UC requires the removal of the colon, or both the colon and the rectum. Then connecting the small intestine and anus. An ileoanal pouch (J pouch) will then be created to collect stool via the anus. Sometimes an ileostomy may be required to collect the stools on the outside of the body
  • Self-management techniques to help manage symptoms and reduce fatigue and pain. This may also include learning triggers for flare-ups and being extra vigilant of symptoms during flare-ups 
  • Lifestyle advice and referral to specialist services if necessary. This could be for things like smoking, pregnancy, nutrition, and employment

There is a higher likelihood of having to undergo invasive surgery or aggressive medical therapy when there is a delay in getting a diagnosis.17 Therefore, it is important that you see a doctor as soon as possible if you are experiencing the signs and symptoms of IBD. 


How is inflammatory bowel disease diagnosed

IBD is often diagnosed after a variety of tests have been performed by your doctor.13 These could include a combination of one or more of the following: lab tests, imaging procedures, and endoscopic procedures. Initially, blood tests and stool tests are performed to identify inflammation and anemia. Afterwards, further testing may be required which could include endoscopic procedures and X-rays. 

How can I prevent inflammatory bowel disease

There are no ways to prevent IBD. However, it is beneficial to get a diagnosis as early as possible to help manage the symptoms. There may be certain factors that  may increase your risk of developing IBD. For example, how your body’s immune system reacts to certain environmental triggers may determine the development of IBD. Types of environmental triggers may include smoking, medications, and stress. 

What are the types of inflammatory bowel disease

There are 2 types of IBD which include: Crohn’s disease and ulcerative colitis. These conditions affect different parts of the body. Crohn’s disease only affects the large intestine (colon), whereas ulcerative colitis can affect any section of the digestive system from the mouth to the anus. However, both conditions are lifelong and have similar symptoms such as fatigue, dehydration, and diarrhea.

Who are at risk of inflammatory bowel disease

There are some risk factors for developing IBD. However, most of these risks cannot be changed e.g., genetics. If you have immediate family members with IBD, you may be more likely to be diagnosed with IBD. Additionally, IBD is more common within Caucasian  and African-American  ethnicities than  those with Asian or Hispanic ethnicity. There is a larger number of people with IBD in the Western world which may be attributable to a variety of factors like the western diet and access to healthcare for diagnosis. 

How common is inflammatory bowel disease

Research shows that 1 in 123 people have either ulcerative colitis or Crohn’s disease in 2022 within the United Kingdom (UK). Nearly  half a million people within the UK have an IBD diagnosis. The diagnosis rate of IBD has also increased by 33% from 2006 to 2016 within the UK, and this is the same with all ages. The prevalence of IBD within the UK is also similar to the rate of IBD within the USA, where 1.3% of people have IBD.  

When should I see a doctor

When you have worrying symptoms like blood in your poo, diarrhea, unexplained weight loss, or unexplained pain and fatigue, there is a possibility that it could be IBD. There is still a need to get your symptoms checked out if your symptoms subside and then return as this can happen within IBD. Moreover, if you do not have any gut problems but are experiencing extreme fatigue, joint pains, weight loss, mouth ulcers, and low iron levels you should see a doctor. If you are unsure whether to see a doctor, then this symptom tracker may help. However, when in doubt about feeling ill, it is always best to see a healthcare professional. 


Inflammatory Bowel Disease (IBD) is a chronic condition that causes inflammation in the gastrointestinal tract. It consists of two main conditions: Crohn's disease and ulcerative colitis. While both conditions have similar symptoms and can occur at any age, there are differences between them. Ulcerative colitis affects the colon and rectum, while Crohn's disease can affect any part of the digestive tract. Remission periods, when symptoms are absent, can occur for varying lengths of time. IBD is commonly diagnosed in individuals aged 14 to 50. It's important to understand the causes, symptoms, and treatments of IBD, and this article aims to provide a simple and comprehensive overview.


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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Kristy Maskell

Master of Science – Nutrition and Dietetics, University of Hull
Bachelor of Science with Honours – Exercise and Health Science, University of Brighton

Kristy is a Dietetics master’s student which has allowed her to develop clinical knowledge of nutrition for a variety of populations. She is passionate about making evidence-based nutrition information accessible and loves to write this for everybody to read. Kristy looks forward to qualifying as a registered dietitian in the near future and having the opportunity to provide the best possible patient-centred care.

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