What is the initial treatment for an acute flare of ulcerative colitis?

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Last updated: June 29, 2025View editorial policy

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From the Guidelines

The initial treatment for an acute flare of ulcerative colitis should involve oral 5-aminosalicylates (5-ASAs) for mild to moderate flares, with a recommended dose of 2-3 g/day, and corticosteroids, such as oral prednisolone, for moderate to severe flares, as supported by the most recent and highest quality evidence 1.

Treatment Approach

For mild to moderate distal colitis, topical mesalamine (1-4g daily) as suppositories or enemas can be highly effective and may be combined with oral mesalamine (2-4.8g daily) 1. In cases of more extensive disease, oral mesalamine at the same dosage is considered first-line therapy. If symptoms do not improve within 2-3 weeks, oral prednisone (40-60mg daily) should be initiated, with a gradual taper over 8-12 weeks once remission is achieved 1.

Severe Flares

For severe flares, hospitalization may be necessary, with treatment including intravenous corticosteroids, such as methylprednisolone 60mg daily or hydrocortisone 300mg daily in divided doses, alongside adequate hydration and nutrition 1. The choice of treatment should be guided by the severity of the flare and the patient's response to initial therapy.

Adjusting Treatment

Treatment should be adjusted based on clinical response, with escalation to immunomodulators or biologics if there is inadequate improvement 1. It is crucial to monitor patients closely and adjust the treatment plan as necessary to achieve and maintain remission, thereby minimizing morbidity, mortality, and improving quality of life.

Key Considerations

  • Mild to Moderate UC: Oral 5-ASAs are the first-line treatment, with topical mesalamine for distal disease 1.
  • Moderate to Severe UC: Corticosteroids, such as oral prednisolone, are recommended for induction of remission 1.
  • Severe UC: Hospitalization and intravenous corticosteroids may be necessary, with careful monitoring and adjustment of treatment as needed 1.

From the FDA Drug Label

For this trial, the endoscopy score definition of 1 (mild disease) was modified such that it could include erythema, decreased vascular pattern, and minimal granularity; however, it could not include friability. Of the 26 patients in the recommended mesalamine dosage arm, 65% achieved the primary endpoint after 8 weeks of treatment Patients were eligible for the initial 8-week phase if they had mildly to moderately active ulcerative colitis as defined by the UC-DAI score of at least 4 with an endoscopic subscore of 2 or 3.

The initial treatment for an acute flare of ulcerative colitis is mesalamine. The recommended dosage is not explicitly stated for acute flare, but for mildly to moderately active ulcerative colitis, 65% of patients achieved the primary endpoint after 8 weeks of treatment with mesalamine 2.

From the Research

Initial Treatment for Acute Flare of Ulcerative Colitis

The initial treatment for an acute flare of ulcerative colitis depends on the severity of the disease.

  • For mild to moderate disease, the following treatments are considered:
    • Aminosalicylates (5-ASA), such as mesalazine, are the first-line therapy 3, 4, 5
    • Topical treatment with mesalazine (mesalamine) is appropriate initial therapy for distal disease 6
    • High-dose aminosalicylates (such as Pentasa, 4 g orally daily and 1 g rectally) are an alternative for symptoms not interfering with daily activity 6
  • For patients with mild ulcerative colitis, oral or topical (rectal) application of aminosalicylates (5-ASA) is the cornerstone of treatment 7
  • For patients with ulcerative proctitis and left-sided colitis, rectal 5-ASA preparations are even more effective than oral administration 7

Treatment Options

The treatment options for acute flare of ulcerative colitis include:

  • Mesalamine with Multi-Matrix System(®) (MMX) technology, an oral (1.2 g), once-daily tablet formulation of mesalamine 4
  • Corticosteroids, which have been the mainstay in Europe for mild to moderate disease 6
  • Azathioprine, which is indicated for patients after a severe relapse of ulcerative colitis, those with early relapse after steroids, and those needing a second course of steroids within a year 6

Considerations

When considering treatment for acute flare of ulcerative colitis, the following should be taken into account:

  • The risk of colorectal tumours is increased in patients with longstanding ulcerative colitis, and epidemiological evidence indicates that chronic 5-ASA treatment reduces this risk 3
  • The use of aminosalicylates in combination with thiopurines or biologic therapy remains under debate 5
  • The timing of colectomy is the most important decision that a physician is called upon to make, in conjunction with the patient and surgical colleagues 6

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

The role of aminosalicylates in the treatment of ulcerative colitis.

Acta gastro-enterologica Belgica, 2002

Research

Modern use of 5-aminosalicylic acid compounds for ulcerative colitis.

Expert opinion on biological therapy, 2020

Research

Review article: the management of mild to severe acute ulcerative colitis.

Alimentary pharmacology & therapeutics, 2004

Research

[Efficient treatment of mild Crohn's disease and mild ulcerative colitis].

Innere Medizin (Heidelberg, Germany), 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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