What Is Acute Ulcerative Colitis?

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For patients with ulcerative colitis, a chronic disease affecting the mucosal lining of the intestine, symptoms may come and go. While it is an incurable disease, mild to moderate symptoms may be managed with diet and medication. Acute ulcerative colitis is when patients experience a severe flare-up of this inflammatory bowel disease. It is a severe medical condition that can be potentially life-threatening without prompt treatment.

Approximately 20 percent of patients diagnosed with ulcerative colitis will experience cases of acute ulcerative colitis that require hospitalization.

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While the exact cause of ulcerative colitis is unknown, research indicates it is likely a complex interaction of various factors that cause an inappropriate immune response in the intestine. Factors that may interact to cause ulcerative colitis include a person's genetics, age, and gut microbiota, toxic pathogens, and the environment.

Some patients with ulcerative colitis are more at risk for experiencing acute ulcerative colitis that requires hospitalization. Risk factors for these severe flare-ups include:

  • Less than 40 years of age at diagnosis
  • Extensive disease (affecting large areas of the intestine)
  • Presence of large or deep ulcers
  • Dependency on corticosteroids
  • No previous appendectomy
  • High levels of inflammation
  • Nonsmokers


Acute ulcerative colitis is a medical emergency, as it indicates the inflammation has spread beyond the lining of the intestine and is impacting the body as a whole (systemic). If you experience symptoms of acute ulcerative colitis, it is important to seek hospitalization. Prompt treatment can be life-saving.

Symptoms of acute ulcerative colitis include:

  • Severe abdominal pain
  • Heavy diarrhea
  • Bleeding
  • Fever
  • Abdominal or colonic distension
  • Signs of systemic toxicity


Acute ulcerative colitis is diagnosed based on the severity of symptoms, lab tests, and imaging. There are two systems used to define acute ulcerative colitis: the Truelove and Witts criteria, and the Mayo Clinic scoring system.

Following the Truelove and Witts criteria, acute ulcerative colitis is defined as:

  • Six or more bloody bowel movements per day

AND at least one of the below:

  • Heart rate greater than 90 bpm (beats per minute)
  • Temperature greater than 37.8 C (100 F)
  • Hemoglobin less than 10.5 g/dL (grams per deciliter), and/or
  • Erythrocyte sedimentation rate greater than 30 mm/h (millimeters per hour)
Truelove and Witts Criteria - Disease Severity Score
 Variable Mild  Severe Fulminant 
Number of stools/day <4 >6 >10
Blood in stool Intermittent Frequent Continuous
Temperature, C Normal >37.5 >37.5
Pulse (bpm) Normal >90 >90
Hemoglobin Normal <75% normal Transfusion required
Erythrocyte sedimentation rate (mm/h) ≤30 >30   >30
Colonic features on radiograph None Air, edematous wall, thumbprinting Colonic dilation
Clinical signs None Abdominal tenderness Abdominal distention and tenderness

Following the Mayo Clinic system, acute ulcerative colitis is defined as:

  • Score of 6-12


  • Endoscopic subscore of 2 or 3
Mayo Clinic Scoring System for Ulcerative Colitis
Stool Pattern Score Most Severe Rectal Bleeding of the Day  Score
Normal number of daily bowel movements 0 None 0
1-2 more bowel movements than normal 1 Blood streaks seen in the stool less than half of the time
3-4 more bowel movements than normal 2 Blood in most stool 2
5 or more bowel movements than normal 3 Pure blood passed 3
 Endoscopic Findings  Score
Normal/inactive colitis  0
Erythema, decreased vascularity
Friability, marked erythema, erosions 2
Ulcerations, severe friability, spontaneous bleeding 3


Optimal treatment of acute ulcerative colitis requires a multidisciplinary team approach including a gastroenterologist specializing in IBD, an abdominal surgeon, a radiologist, the IBD nurse, and a nutritionist.

Intravenous Corticosteroids

The first line of care for acute ulcerative colitis is the use of intravenous corticosteroids.Corticosteroids are a class of drugs that act similarly to the hormone cortisol, which the body naturally produces to reduce inflammation or calm an overactive immune response. Corticosteroids are immediately administered to patients hospitalized for acute ulcerative colitis.

Hydration, Electrolytes, and Nutritional Status

In addition to corticosteroids to reduce inflammation, most patients need intravenous fluids. These treat dehydration and correct electrolyte imbalance due to severe diarrhea, vomiting, and bleeding. Patients are at most risk for hypokalemia and iron deficiency anemia. In some cases, enteral nutrition support may also be helpful.

Immunosuppressive Drugs

For patients who don't respond to corticosteroids after three days, medical rescue therapy with an immunosuppressive drug may be attempted. Drugs typically used include Avsola (infliximab) or cyclosporine. Both drugs have equal effectiveness in medical rescue therapy with 70 percent to 75 percent of patients responsive in the short term and 50 percent in the long term.


Unfortunately, not all patients will respond to medical and rescue therapy, and surgery must be considered within 3 to 5 days for the safety and health of the patient.

Approximately 10 percent to 20 percent of patients admitted to the hospital for acute ulcerative colitis will need a colectomy compared with 30 percent to 40 percent of patients who have been hospitalized one or more times for flare-ups.

Colectomy is the only treatment that will "cure" acute ulcerative colitis. It is the complete removal of the tissue that is inflamed, which prevents future reoccurrence. However, there are consequences. Removal of the colon and/or parts of the intestine results in significant changes in the body's functions as well as potential complications from the surgery.


Acute severe ulcerative colitis is a life-threatening condition associated with significant morbidity and mortality. However, prompt medical treatment of the disease can prevent it. Since the use of corticosteroids, mortality from acute ulcerative colitis has decreased from 30 percent to 40 percent to approximately 1 percent to 2.9 percent.

Approximately 65 percent of patients will respond to corticosteroids administered intravenously. As ulcerative colitis is incurable, the patient's status should be continuously monitored and evaluated.

A Word From Verywell

If you've been diagnosed with ulcerative colitis, speak with your doctor about how you may be able to manage your symptoms and minimize the risk of having a severe flare-up of acute ulcerative colitis.

Timely management is crucial. Learn to catch the early signs and symptoms to ensure the best possible prognosis. If you suspect you are experiencing acute ulcerative colitis, do not hesitate to seek emergency treatment and hospitalization.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rebecca Valdez, MS, RDN
Rebecca Valdez is a registered dietitian nutritionist and nutrition communications consultant, passionate about food justice, equity, and sustainability.