Crohn’s disease (CD) and ulcerative colitis (UC) are the most common inflammatory bowel diseases impacting over 500,000 individuals in the UK, affecting not only their everyday routines but also their overall health and wellbeing [1]. Although awareness of these conditions has improved and there have been advancements in treatment, many individuals living with CD and UC continue to experience gaps in care, support and understanding from both the wider community and healthcare systems.

This article outlines the signs, symptoms and causes of CD and UC, as well as the treatment options available for individuals living with these inflammatory bowel diseases.

What is inflammatory bowel disease?

Inflammatory bowel disease (IBD) refers to a group of conditions characterised by chronic swelling and inflammation of tissues in the gastrointestinal (GI) tract. The main types of IBD are CD and UC [2], both of which are autoimmune disorders that lead to severe and painful complications including:

Ulcerations [2]
Strictures (narrowing of intestines) [3]
Fistulas (abnormal passageways between different parts of the intestines or between the intestines and other organs) [2]
Abscesses (tender growths filled with pus) [2]

CD and UC typically present with similar symptoms including stomach pain, diarrhoea, rectal bleeding, weight loss and fatigue; however, these conditions can affect different areas of the GI tract [2].

CD: patchy inflammation anywhere in the GI tract, often involving deeper layers of the digestive tract [2]

UC: continuous and uniform inflammation in the large intestine only, often involving the intestinal lining [2]

Figure 1: Inflammatory Bowel Disease

The pathogenesis of IBD involves a complex interplay of several genetic, environmental and immune factors affecting the intestinal barrier.

The intestinal barrier consists of two central components: the physical barrier and the chemical barrier [4].

Genetic predisposition to IBD and environmental factors can disrupt the balance of bacteria in the gut, leading to a reduction in beneficial bacteria and an increase in those that are potentially harmful [4].

The imbalance of gut bacteria damages the intestinal barrier, increasing permeability and causing a breakdown of tight junctions between gut epithelial cells [4].

Impaired function of key gut cells such as Paneth cells results in reduced anti‑microbial peptide (AMP) production in CD or altered mucin secretion in UC [4], both of which weaken the physical and chemical barriers of the intestine and thereby allow bacteria to penetrate the intestinal lining.

The breach in the intestinal barrier activates both innate and adaptive immune responses, leading to an inflammatory cascade characterised by the recruitment of immune cells, including increased secretion of secretory immunoglobulin A (sIgA) and other immune mediators [4].

Chronic inflammation resulting from continuous immune activation contributes to the pathogenesis of CD or UC, leading to persistent intestinal inflammation and tissue damage [4].

Disruption of the tightly controlled gut microbiome can lead to IBD.

Compared with normal gut function with mucosal homeostasis, the key characteristics of gut dysbiosis leading to IBD are [4]:

Bacterial overgrowth – altered ratio of beneficial to aggressive species of bacteria
Bacterial translocation through the intestinal lining into sterile intestine tissue
Reduced mucins
Increase in secretion of sIgA

Figure 2: Gut dysbiosis in IBD

Source: Neurath MF et al. 2025 [4]

Common misconceptions about IBD

1. IBD and irritable bowel syndrome (IBS) are the same condition

IBD and IBS share common symptoms, and both are often diagnosed in young adults; however, they are not the same condition. Unlike IBD which involves inflammation of the digestive tract, IBS is a functional GI disorder that affects the behaviour of but does not damage the intestine [5, 6]. Additionally, individuals with IBD can also have IBS.

2. Changes in diet can cure CD or UC

The role of diet in CD and UC remains unclear. For each study that has connected one dietary factor to IBD, another disproves it. Therefore, changes in diet alone may help manage but are unlikely to cure IBD, including CD and UC [5, 7].

3. Stress causes IBD

People with IBD are at higher risk for mental health issues like stress, anxiety and depression, which can in turn worsen gut symptoms, creating a cycle of mutual impact. The gut–brain axis, which involves nerve signals, hormones and the gut microbiome, may help explain the complex relationship between stress and IBD, with stress potentially exacerbating symptoms [8], but more research is needed to elucidate stress as a primary cause of IBD.

What treatment options are available for IBD?

The goal of IBD treatment is to reduce inflammation of the GI tract. The treatment approach may involve a combination of medications to manage both short-term flareups and provide long-term disease control [9].

Treatment*	Treatment effect
Immunosuppressants e.g. azathioprine, mercaptopurine	Suppress immune system activity to reduce the release of inflammation-inducing factors into the GI tract, thereby preventing further tissue damage [9].
Anti-inflammatory medicines
Aminosalicylates (5-ASAs), e.g. mesalamine, balsalazide	Reduce inflammation in the bowel which can promote healing of damaged tissue and alleviate symptoms [9].
Corticosteroids, e.g. prednisolone, budesonide	Suppress immune system activity to reduce inflammation. Often used during flare-ups of IBD [9].
Small molecules e.g. tofacitinib, ozanimod	Target specific pathways involved in inflammation within the intestine. Typically administered orally [9].
Biologics e.g. adalimumab, infliximab	Antibodies that neutralise specific proteins or chemical pathways involved in inflammation. Biologics are more precise than typical immunosuppressants and may be used for more severe cases of CD or UC [9, 10].
Surgical intervention	Resection (removal of a damaged part of the digestive system) or proctocolectomy (removal of the colon and rectum with formation of a stoma) may be recommended for CD and UC, respectively, where other treatments don’t relieve symptoms [9].

*This is not an exhaustive list.

Latest developments and future hopes

Direct access kits for diagnosis

A study led by the University of Exeter, UK, aims to explore whether direct access to stool testing kits (i.e. without needing to visit the doctor) will reduce the time it takes to diagnose CD and UC [11]. The tests, which detect markers such as calprotectin and blood in the stool, may also help differentiate IBD from conditions such as IBS. The goal is to diagnose patients faster, leading to earlier treatment, fewer hospital visits and improved quality of life.

Precision medicine and artificial intelligence

Precision medicine is transforming IBD management by personalising treatment based on individual patients’ disease characteristics using genetic and molecular information to guide treatment decisions.

Artificial intelligence (AI) may have a role in supporting diagnosis, predicting response to treatment and understanding disease progression. Endoscopic AI tools such as EndoBrain® have been developed to enhance detection of abnormal growths or areas of inflammation, improving diagnostic accuracy and reducing variability in IBD assessment [12]. Additionally, generative AI models are emerging as tools for patient education, symptom tracking, personalised treatment guidance and real-time decision support, enhancing patient care and adherence to treatment [12].

This article serves to raise awareness of IBD, notably CD and UC, and outlines the challenges faced by individuals living with these conditions. While the outlook is promising, with a variety of treatment options available to manage IBD, greater efforts are needed to address gaps in care and research is ongoing into treatments targeting novel pathways involved in the pathogenesis and progression of IBD.

The information in this article is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. All content is for general information purposes only. Always seek the guidance of your doctor or other qualified healthcare professional with any questions you may have regarding your health or medical condition.

References

Crohn’s & Colitis UK. New research shows over 1 in 123 people in UK living with Crohn’s or Colitis. Available at: https://crohnsandcolitis.org.uk/news-stories/news-items/new-research-shows-over-1-in-123-people-in-uk-living-with-crohn-s-or-colitis. Accessed April 2025.
Mayo Clinic. Inflammatory bowel disease (IBD): Symptoms & causes. Available at: https://www.mayoclinic.org/diseases-conditions/inflammatory-bowel-disease/symptoms-causes/syc-20353315. Accessed April 2025.
Crohn’s & Colitis Ireland. Stricture or Narrowing of the Bowel in IBD. Available at: https://crohnscolitis.ie/living/strictureandnarrowing/. Accessed April 2025.
Neurath MF, Artis D and Becker C. The intestinal barrier: a pivotal role in health, inflammation, and cancer. Lancet Gastroenterol Hepatol 2025; Epub ahead of print (DOI: 10.1016/S2468-1253(24)00390-X).
net. Myths and Misconceptions. Available at: https://inflammatoryboweldisease.net/what-is-crohns-disease/myths-and-misconceptions. Accessed March 2025.
Crohn’s and Colitis Foundation of America. Inflammatory Bowel Disease vs. Irritable Bowel Syndrome. Available at: ibd-and-IBS-brochure-final.pdf. Accessed March 2025
Faggianil I, Fanizza J, Massironi S et al. The role of diet in inflammatory bowel disease: A comprehensive review of the literature. Best Pract Res Clin Gastroenterol 2025; In press.
Crohn’s & Colitis UK. Mental health and wellbeing. Available at: https://crohnsandcolitis.org.uk/info-support/information-about-crohns-and-colitis/all-information-about-crohns-and-colitis/living-with-crohns-or-colitis/mental-health-and-wellbeing. Accessed March 2025.
Mayo Clinic. Inflammatory bowel disease (IBD): Diagnosis & treatment. Available at: https://www.mayoclinic.org/diseases-conditions/inflammatory-bowel-disease/diagnosis-treatment/drc-20353320. Accessed April 2025.
Crohn’s & Colitis UK. Biologics and other targeted medicines. Available at: https://crohnsandcolitis.org.uk/info-support/information-about-crohns-and-colitis/all-information-about-crohns-and-colitis/treatments/biologics-and-other-targeted-medicines. Accessed April 2025.
Crohn’s & Colitis UK. Using direct access testing kits to reduce the time to diagnose Crohn’s and Colitis. Available at: https://crohnsandcolitis.org.uk/our-work/research-and-evidence/projects-we-have-funded/using-direct-access-testing-kits. Accessed March 2025.
Caballero Mateos AM, Cañadas de la Fuente GA and Gros B. Paradigm shift in inflammatory bowel disease management: precision medicine, artificial intelligence, and emerging therapies. J Clin Med 2025; 14 (5):1536.

Author: Ellen Loft Ι Porterhouse Pathfinders Intern