What is the treatment for right-sided colitis?

Treatment for Right-Sided Colitis

Right-sided colitis (extensive ulcerative colitis extending proximal to the splenic flexure) should be treated with oral mesalazine 2-4 g daily or balsalazide 6.75 g daily as first-line therapy for mild to moderate disease. 1

First-Line Treatment Approach

For mild to moderately active right-sided (extensive) colitis:

• Start with oral aminosalicylates: Mesalazine 2-4 g daily or balsalazide 6.75 g daily are the cornerstone of initial therapy 1
• Once-daily dosing is as effective as divided doses and may improve adherence in real-world practice 1
• Olsalazine 1.5-3 g daily is an alternative, though it has a higher incidence of diarrhea in pancolitis and is better reserved for left-sided disease or patients intolerant of other 5-ASA formulations 1
• Consider adding topical mesalazine enemas (1 g daily) for troublesome rectal symptoms, though topical agents are unlikely to be effective as monotherapy in extensive disease 1

The evidence strongly supports aminosalicylates as first-line therapy, with the 2017 ECCO guidelines 1 and 2004 Gut guidelines 1 consistently recommending this approach. The dose-response relationship is well-established, with higher doses (≥2.4 g/day) showing superior efficacy 2, 3.

Escalation for Inadequate Response

If aminosalicylates fail after an adequate trial (typically 2-4 weeks at optimal dose):

• Initiate oral prednisolone 40 mg daily for patients requiring prompt response or those with mild to moderate disease who have not responded to mesalazine 1
• Taper prednisolone gradually over 8 weeks according to disease severity and patient response; more rapid reduction is associated with early relapse 1
• Topical agents (mesalazine or steroids) may be continued as adjunctive therapy during steroid treatment 1

Steroid-Dependent or Refractory Disease

For patients who become steroid-dependent or have chronic active disease:

• Add azathioprine 1.5-2.5 mg/kg/day or mercaptopurine 0.75-1.5 mg/kg/day as steroid-sparing agents 1
• Long-term steroid treatment is undesirable due to significant side effects and should be avoided 1
• Ciclosporin may be effective for severe, steroid-refractory colitis, though this should be managed in specialist centers 1

Severe Disease Requiring Hospitalization

Patients meeting Truelove and Witts criteria (bloody stool frequency ≥6/day plus tachycardia >90/min, temperature >37.8°C, hemoglobin <10.5 g/dL, or ESR >30 mm/h) require:

• Immediate hospital admission for intravenous therapy 1
• Intravenous hydrocortisone 400 mg/day or methylprednisolone 60 mg/day 1
• Exclusion of infection, particularly Clostridium difficile 1

Important Caveats

• Sulfasalazine 2-4 g daily has a higher incidence of side effects compared to newer 5-ASA drugs and is not recommended as first-line therapy, though it may benefit selected patients with reactive arthropathy 1
• Proximal constipation should be treated with stool bulking agents or laxatives, as this can complicate extensive colitis 1
• Avoid antidiarrheal medications as they can mask worsening symptoms and theoretically predispose to toxic dilatation 4
• Disease activity should be confirmed by sigmoidoscopy and infection excluded before initiating treatment, though treatment need not wait for microbiological analysis 1

Maintenance Therapy

• Lifelong maintenance therapy is generally recommended for all patients with extensive colitis 4, 5
• Aminosalicylates remain effective and safe for long-term maintenance 4, 5
• For steroid-dependent disease, continue azathioprine or mercaptopurine as maintenance immunomodulation 4, 6