A Systematic Review and Meta-Analysis of Randomized Clinical Trials of the Efficacy of Mesalazine in Irritable Bowel Syndrome

Mesalazine (5-aminosalicylic acid, 5-ASA) has been proposed as a therapeutic option for irritable bowel syndrome (IBS) due to its anti-inflammatory properties, but its efficacy remains uncertain. This systematic review and meta-analysis evaluated randomized controlled trials comparing mesalazine versus placebo in adult patients with IBS. A systematic search of PubMed, ScienceDirect, and Google Scholar was conducted up to March 23, 2026. Only the first 100 Google Scholar results sorted by relevance were screened. Risk ratios (RRs) and standardized mean differences (SMDs) were pooled using a random-effects model, and risk of bias was assessed using the Cochrane RoB 2 tool. Seven randomized controlled trials involving 569 participants were included. Mesalazine did not significantly improve global IBS symptom response compared with placebo (RR 1.11, 95% CI 0.93-1.32; I² = 10%). No significant effect was observed for abdominal pain (SMD -0.10, 95% CI -0.82 to 0.61; I² = 83%). However, mesalazine significantly improved global IBS symptom scores (SMD -0.39, 95% CI -0.64 to -0.15; I² = 16%). The overall risk of bias was low to moderate across studies. In conclusion, mesalazine does not significantly improve global IBS response or abdominal pain, but it may modestly reduce overall symptom burden. Further high-quality randomized controlled trials are needed to identify whether selected IBS phenotypes with mucosal immune activation may benefit from mesalazine.