Your personal
AI assistant for
Ulcerative Colitis

What is ulcerative colitis?

‍

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) that causes inflammation and ulcers in the lining of the large intestine (colon) and rectum. This leads to abdominal pain, persistent diarrhoea, rectal bleeding, and urgent bowel movements. It is non-contagious but can significantly affect a person's quality of life.

‍

Unlike Crohn's disease, ulcerative colitis affects only the colon and rectum, and the inflammation is continuous rather than patchy. In more severe cases it can increase the long-term risk of colorectal cancer, making regular monitoring important.

Although it can develop at any age, ulcerative colitis most often first appears between 15 and 35 years, with a second smaller peak in people aged 50 to 70. It affects men and women equally and is most prevalent in Western countries, though rates are rising globally.

‍

Common locations where symptoms appear include the rectum, sigmoid colon, descending colon, and in more extensive cases, the entire colon.

‍

Common symptoms include:

• Persistent diarrhoea, often with blood or mucus
• Urgent and frequent need to use the bathroom
• Abdominal cramping and pain
• Rectal pain or bleeding
• Inability to defecate despite urgency
• Fatigue and low energy
• Unintended weight loss
• Loss of appetite
• Fever during flare-ups
• Nausea
• In children, delayed growth and development

How ulcerative colitis develops

‍

Ulcerative colitis develops when the immune system responds abnormally to the contents of the large intestine, triggering inflammation in the colon's inner lining. Unlike Crohn's, this inflammation stays within the innermost layer of the bowel wall and spreads continuously from the rectum upward through the colon. Over time, the inflamed lining develops ulcers that can bleed and produce mucus or pus.

‍

The exact trigger is not fully understood, but researchers believe it results from a combination of factors:

• Genetics — around 15% of people with UC have a first-degree relative with IBD, and over 200 gene variants have been associated with the condition.
• Immune dysfunction — an overactive immune response treats harmless gut bacteria as a threat, sustaining chronic inflammation in the colon.
• Gut microbiome imbalance — disruptions to the natural balance of bacteria in the large intestine appear to play a role in triggering or perpetuating inflammation.
• Environmental factors — diet, stress, antibiotic use, and urban living have all been linked to higher rates of UC. Interestingly, former smokers have a higher risk than current or never-smokers.

The inflammation in ulcerative colitis follows a relapsing-remitting pattern — periods of active symptoms (flares) alternate with periods of remission where symptoms ease or disappear entirely. Long-term management focuses on maintaining remission and reducing flare frequency.

‍

Types of ulcerative colitis

‍

Ulcerative colitis is classified by how much of the colon is affected. Knowing which type you have helps guide treatment decisions and explains differences in symptom severity between individuals.

• Ulcerative proctitis is the mildest and most common form, affecting only the rectum. Symptoms are often limited to rectal bleeding and urgency, and it tends to respond well to treatment.
• Proctosigmoiditis involves the rectum and the sigmoid colon (the lower end of the colon). It causes bloody diarrhoea, cramping, and an inability to move the bowels despite the urge.
• Left-sided colitis extends from the rectum up through the sigmoid colon and descending colon. It causes diarrhoea, abdominal cramping on the left side, and unintended weight loss.
• Extensive colitis affects the majority of the colon, including the transverse colon and beyond. Symptoms are more pronounced and may include significant diarrhoea, pain, fatigue, and weight loss.
• Pancolitis affects the entire colon and tends to produce the most severe symptoms, including frequent bloody diarrhoea, significant abdominal pain, fatigue, and in some cases, fever and anaemia.

It's worth noting that the extent of disease can change over time — some people with proctitis find that inflammation spreads further along the colon as years pass, which may require adjustments to treatment.

‍