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Ulcerative colitis
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Ulcerative colitis

Ulcerative colitis is a chronic inflammatory bowel disease characterized by recurring ulcers in the inner lining of the large intestine, often leading to abdominal pain and digestive complications.

Overview

Ulcerative colitis is a chronic disorder characterized by abnormal inflammation of the inner surface (epithelium) of the rectum and colon, which make up most of the large intestine. This inflammation typically causes open sores, or ulcers, to develop. While it can develop at any age, it most commonly appears between the ages of 15 and 30. The condition is marked by inflammation that tends to flare up multiple times throughout a person's life.

Symptoms

The most common symptoms include cramping abdominal pain and frequent diarrhea, which often contains blood, pus, or mucus. Other signs and symptoms include:

  • Nausea and loss of appetite
  • Bowel urgency
  • Fatigue and fevers
  • Weight loss
  • Shortage of red blood cells (anemia) due to chronic bleeding
  • Slowed growth in affected children
  • Less common issues involving the skin, joints, eyes, kidneys, or liver

Complications

A rare but life-threatening complication is toxic megacolon, which involves a widening of the colon and an overwhelming inflammatory response. The disorder also increases the risk of developing colon cancer, particularly in individuals with long-term inflammation of the entire colon.

Causes & Risk Factors

The development of ulcerative colitis is likely influenced by a combination of genetic and environmental factors. Researchers believe the condition may stem from a breakdown in the protective function of the intestinal lining or an abnormal immune response to normal bacteria in the intestines.

  • Genetic Variations: Variations in dozens of genes, such as IL23R and IRF5, have been linked to the condition.
  • Immune System: Genetic variations may lead to an overactive immune response or a malfunction where the immune system attacks intestinal cells.
  • Intestinal Barrier: A breakdown in the intestinal barrier may allow bacteria and toxins to contact intestinal tissue, triggering chronic inflammation.

Inheritance

The inheritance pattern of ulcerative colitis is unknown due to the complex involvement of multiple genetic and environmental factors. However, having a family member with the condition increases an individual's risk of developing it.

Frequently Asked Questions

Screening colonoscopies are typically recommended to start 8 years after the initial onset of symptoms for individuals with pancolitis or left-sided colitis. After the baseline screening, surveillance colonoscopies are repeated every 1 to 3 years depending on personal risk factors, including the endoscopic severity of past inflammation, the presence of pseudopolyps or family history of colorectal cancer, and whether the patient has co-existing primary sclerosing cholangitis.
Yes, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, and high-dose aspirin can damage the intestinal mucosal barrier, interfere with gut prostaglandins, and provoke disease flares. Acetaminophen is generally the preferred over-the-counter analgesic for patients with ulcerative colitis, though any new or persistent pain should be discussed with a gastroenterologist before initiating regular therapy.
During an active flare, a temporary low-residue or low-fiber diet can help minimize bowel movement frequency and abdominal cramping. Patients are typically advised to avoid roughage, raw vegetables, seeds, nuts, spicy foods, caffeine, and dairy if lactose intolerant. Once remission is established, individuals should gradually reintroduce a broad, nutrient-dense diet containing soluble fiber to nourish the colonic microbiome, taking care to stay hydrated and address common deficiencies in iron, calcium, and vitamin D.
Toxic megacolon is a medical emergency signaled by severe abdominal distension and tenderness, high fever, a rapid heart rate (tachycardia), lethargy, and mental status changes. Crucially, a sudden decrease in the frequency of bowel movements after severe diarrhea, paired with worsening pain and bloating, can indicate colonic paralysis and dangerous stretching, which carries a severe risk of bowel perforation and peritonitis.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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