Ulcerative colitis is a condition that generally affects the innermost lining (mucosa) of the large intestine (colon). The lining becomes inflamed (red and swollen) and tiny open sores (ulcers) form on the surface of the lining. These ulcers might bleed – in fact, bleeding from the rectum is often a first sign that something’s not quite right. The inflamed lining also produces a larger than normal amount intestinal lubricant or mucus, which sometimes contains pus.

What is IBD?

An inflammatory bowel disease (IBD) is a chronic inflammatory condition that affects parts of the digestive tract, but most commonly involves the small and large intestines. The most common diseases are ulcerative colitis and Crohn’s disease.

Ulcerative colitis affects the large intestine (colon), while Crohn’s disease can affect any part of the gastrointestinal (GI) tract, from the mouth to the anus.

How does Ulcerative Colitis affect the large intestine?

Inflammation ‘attacks’ the innermost lining of the colon known as the mucosa, resulting in bleeding and diarrhoea.

The inflammation is most often located in the rectum and lower colon, but can also involve other parts of the colon, sometimes even the entire colon. Less often, it might involve other parts of the intestine. Depending on the exact location of the inflammation, ulcerative colitis is known by other names:

  • Proctitis: involves only the rectum
  • Proctosigmoiditis: involves the rectum and sigmoid colon (the lower segment of the colon before the rectum)
  • Distal colitis: involves only the left side of the colon
  • Pancolitis: involves the entire colon
  • Backwash ileitis: involves the distal ileum.

What are the signs and symptoms?

The usual symptoms include:

  • Frequent, watery diarrhoea often containing blood, mucus and pus
  • Sense of urgency to have a bowel movement (especially when the rectum is involved)
  • Crampy abdominal pain (often because of constipation in unaffected parts of the colon)
  • Tiredness, fatigue
  • Loss of appetite
  • Weight loss

As the lining of the colon becomes more and more inflamed, it loses its ability to absorb water from the liquid waste that passes through from the ileum. This leads to watery diarrhoea, often containing mucus and pus. Among those affected, many will feel crampy abdominal pain and a strong urgency to have frequent bowel movements. It is common to feel tired and easily fatigued, especially during active phases of the disease. The tiny ulcers in the intestinal lining can easily crack open and bleed.

Over time, blood loss can lead to a significant decrease in the number of red blood cells (a condition known as anaemia), which adds to the tiredness and fatigue.