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Health condition · Clinically reviewed

Inflammatory bowel disease, Crohn, colitis and a modern treatment ladder.

Chronic, treatable and increasingly well-controlled. A specialist-led plan that maps your phenotype, calms the gut and keeps you living the life you want.

A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, BSG and ECCO standards you can see at the end of the page.

  • 03

    Current for 2026

    Reflects modern UK practice including anti-IL-23 biologics, JAK inhibitors and S1P modulators.

Key facts

IBD at a glance.

The essentials, in plain English - what it is, the main types, how common it is, and how the UK treats it today.

  • What it is

    Inflammatory bowel disease is a chronic, relapsing and remitting inflammation of the gut driven by a mix of genetics, microbiome, environment and immune response.

  • The two main types

    Crohn disease is transmural with skip lesions anywhere from mouth to anus. Ulcerative colitis is mucosal, continuous and confined to the colon starting at the rectum.

  • A third category

    Around one in ten cases sits between the two and is called IBD-unclassified until the picture declares itself over time.

  • How common

    Roughly 500,000 people in the UK are living with IBD according to Crohn's & Colitis UK - a peak in the 15 to 30 age band and a secondary peak from 50 to 70.

  • What it feels like

    Diarrhoea, blood or mucus, cramping abdominal pain, weight loss, fatigue, fever and extra-intestinal features involving joints, skin, eyes and liver.

  • How it is treated

    A ladder from 5-ASA and steroids through thiopurines and methotrexate to biologics, JAK inhibitors, S1P modulators and, when needed, surgery.

Why this guide matters

A phenotype-first plan, not a one-size ladder.

IBD is not one disease. Getting the phenotype right - Crohn or ulcerative colitis, location, behaviour and severity - shapes every treatment decision that follows.

  • Diagnosis is a specialist workup

    Faecal calprotectin, bloods, endoscopy with biopsy and MRI enterography together tell you the type, extent and severity.

  • Modern biologics change the story

    Anti-TNF, anti-α4β7, anti-IL-23, JAK inhibitors and S1P modulators have transformed remission rates and quality of life.

  • Surgery is a treatment, not a failure

    For stricturing Crohn or refractory ulcerative colitis, well-timed surgery is often the best route back to health.

How the diagnosis is made

From first symptoms to a clear plan.

The steps a UK gastroenterology team will normally follow, in order, so you know what to expect and why each test matters.

  1. 01

    Assessing

    History and red-flag review

    Bowel-habit change, blood, weight loss, nocturnal symptoms, family history and extra-intestinal features guide the initial suspicion.

  2. 02

    Assessing

    Stool tests

    Faecal calprotectin separates inflammatory from functional causes. Culture and C. difficile toxin exclude infection - a specialist-commissioned pathway.

  3. 03

    Assessing

    Bloods

    Inflammatory markers, full blood count, iron studies, B12, folate and liver function - a specialist-commissioned workup that anchors the diagnosis.

  4. 04

    Confirming

    Endoscopy and biopsy

    Colonoscopy and, when needed, gastroscopy visualise the mucosa and provide the histology that confirms Crohn or ulcerative colitis.

  5. 05

    Confirming

    MRI enterography or CT

    Cross-sectional imaging maps small-bowel disease, strictures, fistulae and perianal involvement - specialist-commissioned per NICE and BSG.

  6. 06

    Planning

    Gastroenterology MDT

    A specialist-commissioned team review sets the phenotype, extent and severity - and the treatment ladder that follows.

  7. 07

    Planning

    Shared plan and monitoring

    Baseline vaccinations, cancer surveillance planning, family planning and a clear plan for flares - all agreed together, in writing.

Typical timeline: a first specialist visit to a settled plan in weeks, not months.

Symptoms

What IBD actually looks like.

The typical mix of gut symptoms and systemic features - and the signs that mean a same-day call to your IBD team or A&E.

  • Diarrhoea

    Frequent, loose stools - often the first symptom and, in ulcerative colitis, typically bloody from the outset.

  • Blood and mucus

    Rectal bleeding or mucus discharge - a classic feature of active ulcerative colitis and left-sided Crohn colitis.

  • Abdominal pain and cramping

    Colicky pain, worse after meals - Crohn tends to sit in the right lower quadrant with terminal ileal disease.

  • Weight loss and fatigue

    Systemic features that track disease activity - a strong signal to escalate investigation and treatment.

  • Fever and night symptoms

    Waking at night to open the bowels or with fever is not functional - it is an inflammatory red flag until proven otherwise.

  • Extra-intestinal features

    Arthritis, uveitis, erythema nodosum, pyoderma gangrenosum and primary sclerosing cholangitis - see our guide to IBD complications.

  • Growth failure in children

    Falling off the growth chart is a paediatric red flag for Crohn - referral to specialist paediatric gastroenterology is essential.

  • Perianal disease

    Fistulae, abscesses and tags around the anus point to Crohn - MRI, seton drainage and biologics are the specialist mainstays.

Treatment

How IBD is treated in the UK.

A ladder that steps up as needed - from 5-ASA and steroids through immunomodulators to biologics, JAK inhibitors, S1P modulators and, when necessary, surgery.

  • 5-ASA (mesalazine)

    First-line induction and maintenance for mild to moderate ulcerative colitis - oral, topical or combined depending on disease extent.

  • Steroids for flares

    Budesonide for ileocaecal Crohn or right-sided disease and prednisolone for wider or more severe flares - short courses, not maintenance.

  • Exclusive enteral nutrition

    Paediatric Crohn first-line induction - a liquid formula diet for six to eight weeks that heals the mucosa without steroids.

  • Thiopurines and methotrexate

    Azathioprine, 6-mercaptopurine or methotrexate - conventional maintenance immunomodulators, often paired with a biologic to reduce immunogenicity.

  • Anti-TNF biologics

    Adalimumab and infliximab for moderate to severe Crohn or ulcerative colitis and perianal fistulising disease - specialist-commissioned.

  • Vedolizumab (anti-α4β7)

    A gut-selective biologic for ulcerative colitis and Crohn - a favoured choice when a lower systemic immune footprint matters.

  • Anti-IL-12/23 and anti-IL-23

    Ustekinumab, risankizumab, mirikizumab and guselkumab - modern interleukin-targeted biologics for Crohn and ulcerative colitis. See our risankizumab clinic.

  • JAK inhibitors

    Tofacitinib, upadacitinib and filgotinib for ulcerative colitis and Crohn - rapid oral options with specific safety monitoring. See our upadacitinib clinic.

  • S1P modulators

    Ozanimod and etrasimod for moderate to severe ulcerative colitis - specialist-commissioned oral therapies with cardiac and infection screening.

  • Surgery

    Resection for stricturing Crohn and colectomy for refractory or dysplastic ulcerative colitis - specialist-commissioned colorectal expertise.

  • Iron and nutrition

    IV iron for iron-deficiency anaemia and dietitian-led support for growth, weight and micronutrients. See our IV iron and bowel-function clinics.

  • Vaccines and surveillance

    Baseline live-vaccine review before immunosuppression, plus a written colonoscopic dysplasia surveillance plan for long-standing colitis.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or IBD team knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Crohn's disease: management (NG129).

  • NICE. Ulcerative colitis: management (NG130).

  • British Society of Gastroenterology (BSG) consensus guidelines on the management of IBD in adults.

  • ECCO. European Crohn's and Colitis Organisation guidelines on Crohn disease and ulcerative colitis.

  • Crohn's & Colitis UK. Information standards and patient resources.

Red flags

When IBD needs urgent attention.

Most flares can be managed at home or in clinic. These are the situations that cannot wait, and where a same-day call or A&E is the right step.

  • Severe flare

    Six or more bloody stools a day with fever, tachycardia or a rising CRP - a medical emergency needing same-day gastroenterology admission.

  • Toxic megacolon

    A dilated, non-obstructive colon in a systemically unwell patient - a surgical emergency in ulcerative colitis and severe Crohn colitis.

  • Bowel obstruction

    Vomiting, distension and no wind or stool in Crohn disease points to a stricture - hospital assessment and imaging are needed the same day.

  • Perianal abscess

    A hot, painful lump around the anus with fever needs urgent surgical drainage - antibiotics alone are not enough.

  • Massive rectal bleeding

    Large-volume bleeding with dizziness or a drop in blood pressure needs A&E - do not wait for a routine appointment.

  • New severe abdominal pain on biologics

    Perforation, abscess or opportunistic infection must be excluded urgently in anyone on immunosuppression or biologics.

  • Growth failure in a child

    A child crossing centile lines with GI symptoms needs urgent paediatric gastroenterology - Crohn is a leading cause.

  • Jaundice or itch

    Cholestatic features raise suspicion of primary sclerosing cholangitis - a specialist-commissioned hepatology referral is warranted.

  • New joint, skin or eye symptoms

    Extra-intestinal features can flare independently of the gut - see our IBD complications guide and involve the specialist team early.

Living with it

A chronic condition, not a life sentence.

Four things that make the biggest day-to-day difference - knowing your pattern, eating with expert help, escalating early and drawing on the community around you.

A quiet reminder

Early rescue beats late repair.

Calling your IBD nurse at the first sign of a flare almost always shortens it and lowers the chance of admission.

  1. 01 Rhythm

    Learn your own pattern

    Most people find their own triggers, warning signs and recovery patterns - track them and share them with your IBD team.

  2. 02 Nutrition

    Eat with a dietitian, not a diet

    There is no one IBD diet - a specialist dietitian can help tailor food to your phenotype, symptoms and phase of disease.

  3. 03 Escalate

    Speak up early in a flare

    Contact your IBD nurse at the first sign of a flare - early rescue treatment prevents hospital admissions and surgery.

  4. 04 Community

    You are not alone

    Crohn's & Colitis UK provides support, employment guidance and a national community of people living with the same condition.

Frequently asked

Everything we get asked about IBD.

Quick answers on diagnosis, biologics, surgery and life beyond a flare.

  • What is inflammatory bowel disease?

    Inflammatory bowel disease is the umbrella term for chronic, relapsing and remitting inflammation of the gut. The two main types are Crohn disease, which is transmural and can affect any part of the gastrointestinal tract with skip lesions, and ulcerative colitis, which is mucosal, continuous and confined to the colon starting at the rectum. Around one in ten people has IBD-unclassified.

  • Is IBD the same as IBS?

    No. Irritable bowel syndrome is a functional disorder without inflammation or damage. Inflammatory bowel disease is an immune-mediated illness with visible inflammation on endoscopy, abnormal blood tests and a real risk of complications. Faecal calprotectin is the simplest first test to help tell them apart.

  • How is IBD diagnosed?

    Assessment follows NICE, BSG and ECCO guidance and combines history, stool tests including faecal calprotectin, culture and C. difficile toxin, bloods, endoscopy with biopsy and cross-sectional imaging such as MRI enterography. All of this sits within a specialist-commissioned gastroenterology pathway.

  • What treatments are available?

    The ladder runs from 5-ASA and steroids for induction through thiopurines and methotrexate to biologics including anti-TNF, vedolizumab and the newer anti-IL-23 agents, JAK inhibitors and S1P modulators. Exclusive enteral nutrition is first-line for paediatric Crohn induction. Surgery is used for stricturing, refractory or dysplastic disease.

  • Will I need surgery?

    Many people never need surgery, but around half of those with Crohn disease and roughly one in five with ulcerative colitis eventually do. Modern biologics and JAK inhibitors have reduced these numbers, but resection or colectomy remains an important option when medical treatment does not control disease.

  • Can I have children with IBD?

    Yes. Fertility is usually normal outside active disease and most modern IBD drugs are compatible with pregnancy under specialist supervision. Planning ahead with your IBD team, obstetrician and, where relevant, a colorectal surgeon gives the best outcomes for you and your baby.

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