Overview

Colitis refers to inflammation of the colon (large intestine). It is a descriptive term rather than a single disease: causes range from infections and reduced blood flow to chronic immune-mediated disorders. Onset, severity and prognosis vary by type. For general background and patient resources see Colitis overview.

Common signs and symptoms

Symptoms typically reflect irritation and impaired function of the colon. People with colitis may experience a combination of:

  • Diarrhea, often persistent and sometimes bloody
  • Cramping abdominal pain and tenderness
  • Urgency to defecate, sometimes with incomplete evacuation (tenesmus)
  • Fever, fatigue, and unintended weight loss
  • Extraintestinal effects such as joint aches or skin changes in some chronic types

For symptom checklists and when to seek care, consult symptoms guide.

Causes and major types

Colitis can be acute or chronic. Common categories include:

  • Infectious colitis — caused by bacteria, viruses or parasites.
  • Ulcerative colitis and Crohn's colitis — forms of inflammatory bowel disease (IBD) driven by immune mechanisms.
  • Ischemic colitis — due to reduced blood flow to the colon.
  • Microscopic colitis — inflammation visible only on biopsy, typically causing chronic watery diarrhea.
  • Pseudomembranous colitis — often associated with antibiotic-related overgrowth of Clostridioides difficile.

More on causes and risk factors is available at causes and risk.

Diagnosis

Evaluation commonly includes medical history, physical exam, blood tests, stool studies to detect infections, and colonoscopy with biopsy to identify the pattern and extent of inflammation. Imaging such as CT can assess complications. Reliable diagnostic pathways are summarized at diagnostic resources.

Treatment and management

Treatment depends on the underlying cause. Infectious colitis may require targeted antimicrobial therapy, while immune-mediated colitis is managed with anti-inflammatory medications, corticosteroids, immunosuppressants or biologic therapies. Supportive care includes fluid replacement, dietary adjustments and symptom relief. Surgery may be needed for severe, unresponsive disease or complications. Practical treatment information can be found at treatment overview and guidance for specific therapies at management options.

Complications, prognosis and prevention

Potential complications include severe bleeding, perforation, toxic dilation, and long-term risks such as an elevated risk of colorectal neoplasia in some chronic inflammatory conditions. Preventive steps focus on hygiene to reduce infectious causes, appropriate antibiotic use, vaccinations where indicated, smoking cessation and regular follow-up for chronic forms. For advice on follow-up and prevention see follow-up and prevention.

Note: This article provides a general overview and is not a substitute for professional medical evaluation. If you suspect colitis, consult a healthcare provider promptly.