IBD Glossary


Abdomen – the part of the body containing the digestive organs, including the stomach, small intestine, large intestine (including the colon), pancreas, liver and gall bladder.

Abscess – a pus-filled area that becomes red, swollen and painful, usually in response to an infection. In people with Crohn’s, abscesses may form in the abdomen or in the anal and rectal area. 

Adalimumab (Humira) – a biologic drug used to treat Crohn’s or Colitis. See anti-TNF drugs

Adhesions – bands of scar tissue that are usually the result of surgery and that attach the area of surgery to another surface, such as a section of the intestine.

Allopurinol – a drug usually used to prevent gout that may be used to affect the metabolism of azathioprine/mercaptopurine, increasing the levels of these IBD drugs in the bloodstream.

Aminosalicylic acid or 5-ASA – a type of drug used to reduce inflammation and decrease the risk of relapse in Crohn’s and Colitis. Types include balsalazide, mesalazine, olsalazine and sulphasalazine.

Anaemia – reduced numbers of red blood cells.  Red blood cells carry oxygen around the body.  Lack of red blood cells can cause tiredness and shortness of breath. In IBD, anaemia may be due to blood loss and/or poor intake or absorption of vitamins or iron. 

Anal fissure – a crack or split in the skin around the anus, which is often painful and may cause bleeding. In Crohn’s Disease, it may become deeper and may be referred to as an ‘anal ulcer’.

Anal sphincter – a ring of muscle surrounding the anal canal, controlling the opening and closing of the anus.

Analgesic – a type of drug used to relieve pain. Commonly called a painkiller, an example is paracetamol.

Antibiotics – drugs used to fight bacterial infections including complications of IBD such as abscesses and fistulas. 

Antidiarrhoeals – medicines such as loperamide (Imodium, for example) that slow down muscle contractions of the gut. This makes food move through more slowly and allows more water to be absorbed so stools (faeces) become firmer and less urgent.

Anti-TNF drugs – a category of biologic drug used to treat IBD. Anti-TNF drugs work by blocking the effects of TNF-alpha, an inflammatory substance in the blood produced in excessive amounts in some people with IBD. Examples are infliximab and adalimumab.

Anus (back passage) – the opening at the lower end of the gastrointestinal tract, at the end of the rectum. The anal canal is the short passage that connects the anus to the rectum.

Appendix – a narrow tube-like pouch attached to the caecum (see below). 

Arthritis – inflammation of a joint, causing pain, swelling and stiffness. The pain in the joints can be called arthralgia. 

Azathioprine (Imuran) – an immunosuppressant drug used to treat IBD. This drug acts slowly and is generally used for years rather than months.


Balsalazide (Colazide)– a 5-ASA drug used for treating IBD in the colon.

Barium enema – a type of investigation used to examine the colon.  A white liquid containing barium is put into the colon via the anus in order to coat the bowel lining. This helps to give a clear x-ray image of the bowel.

Beclometasone dipropionate (BDP) (Clipper) – a steroid drug, often used short-term in combination with a 5-ASA drug to treat Ulcerative Colitis. It is taken orally in capsule form with a special coating so that the drug reaches the targeted area of inflammation without dissolving in the stomach. This local action can reduce side effects on other parts of the body.

Biologic – a type of drug that can be used to treat IBD. See Anti-TNF drugs, Vedolizumab and Utekinumab.

Biopsy – a small piece of tissue taken from the body for examination under a microscope. These are often taken during colonoscopies to diagnose IBD.

Biosimilar – a biologic drug that is highly similar to another approved biologic medicine, but manufactured by a different company.

Budesonide (Entocort/Budenofalk)– a corticosteroid drug that can reduce inflammation in the intestine. When taken orally, it is designed to release the drug within the ileum. This local action can reduce side effects on other parts of the body. It can also be given through the rectum as an enema.


Capsule endoscopy – an investigation to examine the digestive system, particularly the small intestine. A small capsule containing a tiny camera is swallowed. As it passes through the intestinal tract it takes photographs that are transmitted to a data recorder worn by the patient. The capsule should pass out of the body naturally in a bowel movement.

Chronic (illness) – an illness or disease that is ongoing or continues for a long time (months or years).

Ciclosporin (Sandimmun/Neoral) – an immunosuppressant drug used for severe UC, usually to help avoid or delay surgery to remove the large bowel.

Ciprofloxacin (Ciproxin) – an antibiotic drug sometimes used for Crohn’s Disease.

Clinical trial/research trial – a study to investigate a treatment or test, which could ultimately lead to improvements in IBD management.

Cobblestoning – the characteristic appearance of the bowel mucosa (lining) seen in Crohn’s Disease that looks like cobblestones. It is formed by deep ulceration and swelling of the surrounding tissue.

Codeine phosphate – a painkilling drug also used to help control diarrhoea. It works by reducing the number of contractions in the bowel in order to slow down and reduce the frequency of passing stools.

Colectomy – surgical removal of the colon.

Colitis – inflammation of the colon.

Collagenous Colitis – a form of Microscopic Colitis in which the lining of the colon develops a thicker than normal layer of collagen, a protein.

Colon  – the part of the large intestine that absorbs water from undigested food waste to form a normal stool. 

Colonoscopy – an examination of the rectum, colon and last part of the small intestine (terminal ileum) using a narrow tube with a camera in its tip, sometimes called a colonoscope, which is inserted through the anus.

Colostomy – an artificial opening where the colon is brought through the abdominal wall to create an opening called a stoma. Digestive waste is then collected in a bag that is fitted over this opening and attached to the skin. A colostomy may be temporary or permanent.

Constipation – reduction in the number of times stools are passed. The stools are hard, dry and lumpy, and can be painful to pass.

Corticosteroids – a group of hormones used as a drug treatment to control IBD. These include prednisolone, budesonide and hydrocortisone.  Also known as steroids.

Crohn’s Colitis – Crohn’s Disease in the colon.

Crohn’s Disease – an Inflammatory Bowel Disease that may affect any part of the digestive system from the mouth to the anus.  All the layers of the lining of the bowel may become sore and inflamed.

CRP (C-reactive protein) – a protein in the blood that is often measured to check for active inflammation.  

CT scan (computerised tomography) – an x-ray test that uses a computer to produce pictures that show slices or cross-sections of the body.


Dehydration – a condition caused by lack of water that can cause headaches, tiredness and dizziness. This can occur if you lose too much liquid from the body through vomiting or diarrhoea, are not drinking enough fluids, or have had your large intestine removed.

DEXA (dual energy x-ray absorptiometry) scan – a scan that measures the density of bones to assess bone thinning and the risk of fractures.

Diarrhoea – frequent and often urgent passing of loose or watery stools. It is usually defined as passing such stools 3 or more times a day.

Dietitian – someone who is trained and qualified to advise people about a healthy and appropriate diet. Qualified dietitians are registered with the Health Professions Council.

Distal or left-sided colitis – inflammation that extends up the left side of the colon, but not into the transverse (top) or right side.

Distension – an uncomfortable, swollen feeling in the abdomen, often caused by gas and fluid in the intestine.


Electrolytes – salts in the blood, such as sodium, potassium and calcium.

Endoscopy – a general term for the examination of the inside of the body using a tube with a camera in its tip, called an endoscope, which is inserted through the mouth or anus. The endoscopist carrying out the examination is a specially trained physician, surgeon or nurse. (See gastroscopy, colonoscopy and sigmoidoscopy.)

Enema – a liquid or foam inserted into the large bowel through the anus, for diagnosis or treatment.

Enteral nutrition – a way to provide extra or total nutrition. A specially designed, easily digestible but highly nutritional liquid food is taken by mouth or passed into the stomach through a nasogastric tube (a flexible tube inserted through the nose).  

Erythema Nodosum – red, tender swellings occasionally seen on the shins and lower legs during a flare-up of IBD. These usually go down when the disease is in remission.

ESR (Erythrocyte Sedimentation Rate) – a blood test used to measure inflammation in the body. 

Exacerbation – a worsening of symptoms or an increase in the activity of the disease, often referred to as a relapse or a ‘flare-up’.

Extra-intestinal manifestations – symptoms outside of your digestive system that may appear as part of your IBD, for example uveitis or erythema nodosum. 


Faecal calprotectin – specific proteins found in the stools (faeces). Increased levels of these proteins can be a sign of active inflammation. A faecal calprotectin test is a simple stool test recommended for distinguishing between inflammatory bowel diseases, such as Crohn’s Disease and Ulcerative Colitis, and non-inflammatory bowel diseases, such as Irritable Bowel Syndrome.

Faecal transplant – procedure aimed at restoring a healthy balance of bacteria in the gut. It works by introducing intestinal bacteria from the faeces of a healthy donor into the recipient’s gut. 

Faeces (stools, motions, poo) – waste matter from digestion passed out through the anus or stoma.

Fatigue – a symptom of IBD involving persistent physical or mental exhaustion that is more than normal sleepiness. 

FBC (full blood count) – a blood test that measures red blood cell count, white cell count and platelet count. Used to detect inflammation and anaemia, and also for monitoring patients on long-term medication.

Ferritin test – a blood test that measures iron levels in the body. A low level may indicate the need for iron treatment (see anaemia).

Fistula – an abnormal channel  connecting two loops of intestine, or the intestine to the skin or another organ such as the bladder or vagina

Flare-up – a relapse or exacerbation of a medical condition in which symptoms are more troublesome. IBD often involves periods of remission, in which symptoms are mild or unnoticeable, and periods of active inflammation and symptoms referred to as flare-ups.

Folic acid or folate – a vitamin that is essential for forming red blood cells, especially during times of growth and cell division, such as infancy and pregnancy. A lack of this vitamin can result from a poor diet or poor absorption by the small intestine. 

Fulminant colitis – a very intense and severe form of colitis that can happen suddenly.


Gastroenterologist – a doctor who is specially trained in the diagnosis and treatment of intestinal disorders, including Crohn’s Disease and Ulcerative Colitis.

Gastroscopy – an examination of the oesophagus, stomach and duodenum that is sometimes referred to as an Upper GI endoscopy. It uses a slim tube with a camera in its tip, usually called a gastroscope, which is inserted through the mouth.

Golimumab (Simponi) – a biologic drug used to treat IBD. See anti-TNF drugs.


Haemoglobin – a substance in red blood cells that carries oxygen around the body.

Haemorrhoids – swollen veins in or around the anus that bleed easily and can become painful. Commonly known as piles.

Hepatic flexure – the part of the colon where the ascending and transverse colon meet near the liver.

Hydrocortisone – a corticosteroid drug that reduces inflammation. 


IBD – Inflammatory Bowel Disease.

IBD nurse – nursing member of the IBD team with specialist training and knowledge of IBD, who can provide support for people affected by IBD.

IBD Unclassified (IBDU) – also known as indeterminate colitis, or as colitis of uncertain type or etiology (CUTE). You may be described as having IBDU if it is unclear whether you have UC or Crohn’s Disease.

IBS – Irritable Bowel Syndrome – IBS is sometimes confused with Inflammatory Bowel Disease, but is a different condition. Some of the typical symptoms of IBS, such as diarrhoea and abdominal pain, can be very similar to those of IBD – but IBS does not cause inflammation or bleeding.

Ileal pouch-anal anastomosis (IPAA) – a surgical operation to create an internal pouch after removal of the colon. The pouch is made from the ileum and attached to the anus. This means you can pass stools through the anus in the usual way. Sometimes called restorative proctocolectomy or ‘j-pouch’.

Ileocaecal valve – a valve at the joining of the small and large intestines that prevents food residue flowing back to the ileum from the colon.

Ileorectal anastomosis – a surgical operation for IBD after removal of the colon. The end of the ileum is attached to the rectum.

Ileostomy – a surgical opening where the ileum is brought through the abdominal wall to create an opening called a stoma. Digestive waste is then collected in a bag, which is fitted over this opening and attached to the skin. An ileostomy may be temporary or permanent.

Ileum – the lower part of the small intestine, which joins the colon at the ileocaecal valve. Inflammation of the ileum is known as ileitis.

Immune system – the body’s defence system. This is made up of different types of tissues and cells that protect the body against infectious or other harmful organisms that may cause disease. It responds by recognising and attacking antigens. 

Immunosuppressants/immunomodulators – drugs such as azathioprine that reduce inflammation over long periods of time by suppressing the immune system.

Incontinence – unintentional passing or leakage of stools and/or urine.

Inflammation – the way the body responds to irritation, infection or other injury. Blood collects in affected areas, causing reddening, swelling and pain.  

Infliximab (Remicade, Inflectra, Remsima) – see anti-TNF drugs.

Infliximab trough level – the concentration of Infliximab in the blood, measured just before the next dose is due.

Infusion – a procedure to inject a liquid directly into the bloodstream. This could be blood, or a liquid drug such as infliximab. The fluid flows from a sterile bag through plastic tubing and a small needle into a vein.

Intestines – a long, continuous tube running from the stomach to the anus where most absorption of nutrients and water takes place. See small intestine and large intestine.

Intramuscular – into a muscle.

Intravenously – into a vein. Sometimes abbreviated to IV.


Jejunum – the section of small bowel between the duodenum and the ileum.



Lactose intolerance – a common digestive disorder in which a sugar found in milk known as lactose is not broken down, due to a lack of or reduced lactase, which is an enzyme in the small intestine that digests lactose. Lactose intolerance causes abdominal discomfort, diarrhoea and gas after drinking milk or eating milk products. This may affect people with IBD and can often be managed with a diet avoiding cow’s milk.

Laparoscopy – a procedure in which a lighted instrument called a laparoscope is passed through a small cut in the abdominal wall to examine internal organs or to carry out surgery.  Also known as key-hole surgery.

Large intestine –  the part of the intestine that comes after the small intestine in the digestion process. It is where nutrients are absorbed and faecal matter is formed. It includes the colon, rectum and anal canal.

Laxative – a substance that helps you to have a bowel movement. Different types of laxatives act in varying ways to clear the bowel.

Leucocytes/leukocytes – white cells in the blood that help to fight infection.  Leucocytosis is an increased number of white cells in the blood, while leucopaenia is a decrease in the number of white cells in the blood.

LFTs (liver function tests)– blood tests that measure a specific group of proteins and enzymes found in the blood to show how well the liver is working.

Liver – the largest gland in the body, with many functions. Its main function is to regulate chemicals in the blood.

Lymphocytic Colitis – a form of Microscopic Colitis in which there is an increased number of particular white blood cells (called lymphocytes) within the lining of the colon.


Maintenance therapy – treatment (usually one or more drugs) taken long-term to keep an illness in remission.

Malabsorption – the failure to fully absorb the nutrients in food through the intestines.  Malabsorption may result in malnutrition.

6-mercaptopurine (6-MP) (Purinethol) – an immunosuppressant drug closely related to azathioprine, used to treat IBD.

Mesalazine – the generic name for one of the 5-aminosalicylic acid (5 ASA) group of drugs.  Brand names include Asacol, Ipocol, Mesren, Mezavant XL, Pentasa, Octasa and Salofalk.

Methotrexate – an immunosuppressant drug used to treat IBD when azathioprine or 6-MP cannot be tolerated.

Metronidazole (Flagyl)– an antibiotic that may be used to treat inflammation in Crohn’s Disease, fistulas and infections.

Microscopic Colitis – a form of Inflammatory Bowel Disease in which the appearance of the bowel lining appears normal to the naked eye, for example in an endoscopy. Inflammation is only seen when samples of bowel lining are looked at under a microscope.

MRI (magnetic resonance imaging) scan – an examination of internal organs using strong magnets and radio waves rather than x-rays.  A computer converts signals from the scanner into detailed images. There is no radiation involved in this test.

Mucus – a white jelly-like fluid produced by the mucosa (the lining of the intestines). People with Ulcerative Colitis may have a lot of mucus in their stools.

Mycophenolate mofetil (Cellcept) – an immunosuppressant drug occasionally used to treat IBD when azathioprine or 6-MP cannot be tolerated.


Nasogastric tube – see enteral nutrition.

NICE (National Institute for Health and Care Excellence) – an organisation that provides national guidance and advice to improve health and social care.

NSAIDs (non-steroidal anti-inflammatory drugs) – painkillers often used for arthritis, such as ibuprofen and diclofenac. There is some evidence that they may make IBD worse.


Obstruction – a blockage of the small or large intestine, often due to a narrowing or stricture.

Oesophagus or esophagus (gullet) – the part of the digestive system from the throat to the stomach down which food passes.

Olsalazine (Dipentum) – a 5-ASA drug used for treating Ulcerative Colitis.

Oral Crohn’s– Crohn’s Disease in the mouth.

Osteoporosis – thinning of the bones that may cause weakness and higher risk of fractures.  It is more common in IBD than in the general population, and may be caused by long-term use of corticosteroids, severe active disease or by low levels of oestrogen (female sex hormones). Osteopenia is a mild weakness or thinning of the bones, which is not as severe as osteoporosis.

Ostomy – an artificial opening of the intestine onto the wall of the abdomen (see stoma).


Pancolitis – inflammation of the entire colon.

Parenteral nutrition – a method of giving a specially prepared liquid food into a vein when nutrients cannot be absorbed through the intestines. Also called total parenteral nutrition or TPN.

Perforation – an abnormal opening in the bowel wall that causes the contents of the bowel to leak into the normally sterile abdominal cavity.

Perianal – the area around the anal opening, that is, around the anus.

Peristalsis – the wave-like muscle contractions that move food through the digestive system.

Polyp – a fleshy growth that juts out from the lining of the intestines.

Pouch (ileo-anal) – an internal pouch or reservoir made from the lower part of the intestine (ileum) and attached to the anus. This allows stools to pass through the anus in the usual way.

Pouchitis – inflammation of an ileo-anal pouch.

Prebiotic – a natural, non-digestible, substance found in certain foods, such as bananas and leeks, that stimulates the growth and activity of beneficial bacteria in the intestines.

Prednisolone – a corticosteroid drug used to reduce inflammation in IBD. It can be given in tablet form, by injection into a vein, or by an enema or suppository through the rectum. See corticosteroids.

Primary sclerosing cholangitis – rare disease affecting people with IBD in which the bile ducts can become inflamed, and the liver can eventually be damaged.

probiotics– bacteria found in supplements or food products, such as some yoghurts, that may improve the balance of bacteria in the gut.

Proctitis – inflammation in the rectum.

Proctocolectomy – the surgical removal of the colon and rectum. (See total colectomy).

Proctosigmoiditis – inflammation of the rectum and lower colon.

Pus – a thick white, yellow or greenish fluid, made up of dead white blood cells, found in abscesses, on ulcers, and on inflamed or discharging surfaces.

Pyoderma Gangrenosum – a chronic skin condition with painful ulcers, most often found on the legs, that can affect people with IBD.



Radiologist – a doctor who specialises in interpreting x-ray, ultrasound and other types of imaging or scanning examinations.

Rectal bleeding – any blood that is passed out through the anus.

Rectum – the last part of the large intestine.

Red blood cells or erythrocytes – blood cells containing haemoglobin that carry oxygen from the lungs to the tissues and return carbon dioxide to the lungs.

Relapse – return of disease activity after it has been inactive. Often called a ‘flare-up’.

Remission – a period of good health, free of active disease, with few or no symptoms.

Resection – the surgical removal of a part of the intestine.

Restorative proctocolectomy – see ileal pouch-anal anastomosis.

Rheumatologist – a doctor with special training in the diagnosis and treatment of patients with diseases of the joints and muscles.

Right hemicolectomy – an operation to remove the terminal ileum and caecum.


Sacroiliac joints – joints in the lower back between the pelvis and the spine. These may become inflamed and painful in some people with IBD. This condition is called sacro-ilitis.

Septicaemia – a bacterial infection of the blood, commonly known as blood poisoning or sepsis.

Seton – a loop of thread or rubber band passed through an anal fistula to allow pus to drain and to encourage healing.

Short bowel syndrome – where the bowel does not have enough surface area to absorb sufficient nutrients. This may occur if large sections of the small intestine have been removed.

Sigmoid colon – the lower end of the colon, connecting the descending colon to the rectum.

Sigmoidoscopy – an examination of the rectum and the lower colon using a short tube with a camera in its tip, called a sigmoidoscope, inserted through the anus.

Small bowel enema – a type of test or investigation in which liquid barium and air are passed into the small intestine through a fine tube inserted into the nose or mouth. This helps give clearer x-ray images.

Small intestine – the section of the intestines that digests food and absorbs nutrients after they have passed through the stomach. The small intestine is divided into three parts: the upper region – called the duodenum; the middle region – the jejunum; and the lower region – the ileum.

Splenic flexure – the part of the colon where the transverse and the descending colon meet (below the spleen).

Steroids – see corticosteroids.

Stoma – a surgically constructed opening of the intestine onto the abdominal wall, over which a bag can be fitted and sealed to the skin for waste matter to drain into.

Stricture – a narrowing of a section of the bowel due to bowel wall thickening, inflammation or scarring.

Stricturoplasty – an operation to widen a narrow section of the bowel, so that food matter or waste can pass through more easily. 

Sulphasalazine (Salazopyrin) – a drug that combines 5-ASA with sulphapyridine. It is often used to treat UC, and occasionally for Crohn’s Colitis. 

Suppository – a bullet-shaped capsule of a drug preparation that is inserted into the body through the anus into the rectum. This allows the drug to act directly on the affected area.


Tacrolimus (Advagraf/Prograf) – an immunosuppressant drug, similar to ciclosporin, used for severe IBD.

Tenesmus – a constant urge to have bowel moments, even when the bowel is empty, usually caused by inflammation of the rectum.

Terminal ileum – the last part of the small intestine before it joins the large intestine.

Topical treatment – drug treatment applied directly to an affected area of the body. In IBD this usually refers to the use of suppositories and enemas to treat inflammation in the rectum or the lower section of the colon.

total colectomy – see proctocolectomy.

total colitis – see pancolitis.  

Toxic megacolon – widening or swelling of the colon that may cause perforation, sometimes seen in a very severe attack of Ulcerative Colitis or Crohn’s Colitis. 

TPMT (thiopurine methyltransferase) – an enzyme in blood that can be measured in a test to help predict the possibility of side effects from thioprine drugs, such as azathioprine or 6-MP.

TPN – total parenteral nutrition. See parenteral nutrition.


U&E (urea and electrolytes) – a blood test that mainly checks kidney function.

Ulcerative Colitis (UC) – an Inflammatory Bowel Disease in which the inner lining of the colon and/or rectum becomes inflamed and ulcerated.

Ultrasound scan – a painless test using high-pitched sound waves to produce pictures of organs in the body. In IBD it may show inflamed parts of the intestine or an abscess in the abdomen.

Ustekinumab (Stelara) – biologic drug used to treat IBD by targeting two specific, naturally occurring proteins that play a key role in inflammatory and immune responses. See biologic.

Uveitis – inflammation of the eyes that causes redness or soreness, and can affect people with IBD.


Vedolizumab (Entyvio) – a biologic drug used to treat IBD by blocking white blood cells. See biologic.

Vitamin D – a vitamin produced by the action of sunlight on our skin that is essential for bone health. IBD can sometimes lead to a deficiency of vitamin D, and supplements are sometimes necessary.



X-Ray – an electromagnetic ray that passes through the body to produce pictures of the inside of the body on photographic film. Bones, muscles and organs absorb different amounts of radiation, so the pictures show different body parts in varying shades of light and dark.



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