Browse glossary terms by topic area

Ulcerative colitis (UC) – One of two inflammatory bowel diseases (IBD) characterized by chronic inflammation. With UC, the buildup of inflammation occurs in the colon, which can cause colon damage and UC symptoms. 

• When you have UC, chronic inflammation can be present even when you are not experiencing UC symptoms. Chronic inflammation can be controlled with treatment options that work for you.

Autoimmune disease – A chronic condition where the immune system mistakenly attacks healthy cells. UC is a chronic disease that causes excessive inflammation in the colon contributing to colon lining damage and UC symptoms 

Colon – An organ in the digestive system that absorbs water and other elements from partially digested food to form stools that are passed out of the body. The colon is also known as the large intestine 

Colon damage – The presence of blood, erosions, and/or ulcers in the colon, caused by excess inflammation 

Flare-up – A period when someone with UC experiences attacks of inflammation and associated symptoms. The buildup of inflammation that damages the colon is one factor that can contribute to flare-ups 

Gastrointestinal (GI) tract – The pathway that starts from the mouth and follows through the organs of the digestive system ending with the anus. It’s responsible for transporting and digesting food through the body, absorbing water and nutrients and processing waste

Immune system – The body’s system of fighting off invaders that can make someone sick

Inflammation – Your immune system’s natural defense to harm, such as redness or swelling. When you have UC, your immune system can cause chronic inflammation, contributing to colon damage and UC symptoms 

Inflammatory bowel disease (IBD) – A family of diseases that involve chronic inflammation of the digestive tract. UC is one of the two types of IBD. IBD is not the same thing as irritable bowel syndrome (IBS), which can have similar symptoms but does not involve chronic inflammation

Severity – With UC, severity is determined by colon lining inflammation and damage, your UC disease history, and how greatly UC impacts you, including your measurable symptoms. This is in addition to your gastroenterologist confirming that you have “moderate to severe UC,” which is based on your stool frequency and the presence of blood in your stools 

Ulcer – An open sore and a common characteristic of UC, in which ulcers happen in the lining of the colon 

Biopsy – A medical procedure where a piece of tissue from the body, such as the colon, is collected and examined in a laboratory. Biopsies can be taken during an endoscopy to check for inflammation or damage to the colon that is visible only with a microscope

Colonoscopy – An exam that uses a small camera entering through the anus to look at the colon and/or rectum and help diagnose and monitor the severity of UC

Endoscopy – A procedure where a flexible tube-like instrument with a light and lens for viewing is used to look at the inside of the GI tract by entering through the mouth or anus to monitor your disease and potential complications

Gastroenterologist – A doctor who specializes in issues of the gastrointestinal tract, including inflammatory bowel diseases (IBD) like UC

Mayo score – A score that looks at four categories (stool frequency, rectal bleeding, endoscopy, and an assessment by your healthcare provider) to measure the severity of someone’s UC at diagnosis. After diagnosis, a Mayo score can be used to assess severity over time and whether treatment is working

Aminosalicylates (5-ASAs) – Drugs that contain 5-aminosalicylic acid (5-ASA) and decrease inflammation in the lining of the colon

Biologics – Substances made from living organisms or their products and given by infusion or injection for the prevention or treatment of various diseases. Biologics are also called biologic agents

Colectomy – A type of surgery that removes part or all of the colon

Corticosteroids (Steroids) – Medications that help keep the immune system in check by limiting the body’s ability to initiate and maintain the inflammation process

Immune modifiers (Immunomodulators) – Medications that modify the body’s immune system activity to stop it from causing ongoing inflammation

Janus kinase (JAK) inhibitor – A medication that works by targeting JAKs, some of the proteins involved in inflammation. RINVOQ is an example of a JAK inhibitor taken orally as a once-daily pill

Mechanism of action (MOA) – The process of how a drug works inside the body

Mucosal healing –The absence of blood, erosions, and ulcers in the colon, and the combination of findings from endoscopy (nonsurgical procedure used to visually examine a person's digestive tract) and histology (the study of tissues and cells under a microscope)

Proctocolectomy – A type of surgery that removes the colon and rectum

Remission – A period when someone experiences few or no UC symptoms and their colon lining has visibly improved. Your gastroenterologist can confirm if you're in remission based on the frequency of your bowel movements, a lack of bloody stools, and a visible improvement of the colon lining seen in endoscopy results. Consider treatment options that offer lasting remission, even at 1 year

Small molecule – A drug that can enter cells easily because it has a low molecular weight. Many medications that interact with specific components in your body are small molecules

Treatment response – In UC, treatment response is a reduction in UC symptoms and/or an improvement in overall colon appearance, specifically caused by taking medication (as opposed to other factors like diet or exercise)