Colitis is a term for inflammation of the large intestine, also known as the colon, which occurs when its inner lining becomes swollen. It is not a single disease but a broad label for a group of conditions that cause the colon to become inflamed. The inflammation can be a temporary issue that resolves on its own or with simple treatment, or it can be a chronic, long-term problem.
Common Symptoms of Colitis
The signs of an inflamed colon vary depending on the specific cause and severity. One of the most common experiences is abdominal pain, which can range from mild discomfort to severe cramping. This pain is often accompanied by changes in bowel habits, most frequently persistent diarrhea that may contain blood or mucus. Individuals might also feel a frequent and urgent need to have a bowel movement. Beyond digestive issues, colitis can lead to unintended weight loss, loss of appetite, fatigue, and in some cases, a fever as the body responds to the inflammation.
Types and Causes of Colitis
A primary category is Inflammatory Bowel Disease (IBD), which includes ulcerative colitis and Crohn’s disease. These are chronic conditions where the body’s own immune system mistakenly attacks the digestive tract, leading to persistent inflammation. While ulcerative colitis specifically targets the colon’s innermost lining, Crohn’s disease can affect any part of the gastrointestinal tract and all layers of the bowel wall.
Another form is infectious colitis, a temporary condition caused by an invading microorganism. Bacteria such as Salmonella, E. coli, or Clostridioides difficile (C. diff) can cause acute inflammation from consuming contaminated food or water. Viruses and parasites are other potential culprits. This type of colitis resolves once the infection is cleared, often with antibiotics for bacterial causes.
A different cause of inflammation is a sudden reduction of blood flow to the colon, a condition known as ischemic colitis. This occurs when blood vessels supplying the colon become blocked or narrowed, often due to blood clots or atherosclerosis. Ischemic colitis is more common in older adults and can cause sudden, severe abdominal pain.
Microscopic colitis is a unique type that cannot be seen with the naked eye during a colonoscopy. There are two main subtypes: lymphocytic colitis, characterized by an increased number of white blood cells called lymphocytes in the colon lining, and collagenous colitis, identified by a thicker-than-normal layer of collagen just beneath the lining. The exact causes of microscopic colitis are not fully understood but are thought to involve an abnormal immune response.
How Colitis Is Diagnosed
Determining the presence and specific type of colitis begins with an evaluation of a person’s medical history and symptoms. A physician will conduct a physical examination to check for abdominal tenderness or other physical signs. This initial assessment helps guide the subsequent diagnostic steps.
Blood tests can reveal markers of inflammation and check for anemia from chronic bleeding in the colon. A stool sample analysis is also important to rule out infectious causes, such as bacteria or parasites, which can mimic the symptoms of other forms of colitis.
To directly visualize the inner lining of the colon, a physician will perform an endoscopic procedure. A colonoscopy allows the doctor to view the entire length of the colon, while a sigmoidoscopy examines only the lower part. During these procedures, the doctor looks for redness, swelling, ulcers, or bleeding.
A biopsy is often the most definitive step for diagnosing many types of colitis. During the endoscopy, small samples of tissue are taken from the colon lining and sent to a laboratory for examination under a microscope. This analysis is required for identifying microscopic colitis and can help differentiate between other types, such as Crohn’s disease and ulcerative colitis.
General Treatment Approaches
The management of colitis is highly dependent on its specific type and cause. For colitis caused by bacterial infections, a course of antibiotics is prescribed to eliminate the pathogen. For chronic, autoimmune forms like ulcerative colitis and Crohn’s disease, the goal is to control the inflammatory response with medications such as anti-inflammatory drugs, immunosuppressants, or biologics.
In addition to medication, dietary and lifestyle modifications can help manage symptoms. While diet does not cause most forms of chronic colitis, certain foods can exacerbate symptoms during a flare-up. A doctor might recommend a low-fiber diet temporarily to reduce bowel irritation. Maintaining adequate hydration is also important, especially for those experiencing persistent diarrhea.
In situations where chronic colitis is severe, does not respond to medication, or leads to complications, surgery may be considered. For some individuals with severe ulcerative colitis, a colectomy, which is the surgical removal of the colon, is a necessary procedure. This is viewed as a last resort after other treatment avenues have been exhausted.