Background: Irritable bowel syndrome (IBS), defined according to the Rome IV diagnostic criteria, is a chronic functional gastrointestinal disorder characterized by recurrent abdominal pain related to altered bowel habits. First-line recommended treatments are limited to combining drugs targeting predominant symptoms, particularly pain (antispasmodics), constipation (laxatives), and diarrhea (loperamide), yielding only a limited therapeutic gain. GASTRAP® DIRECT is a class IIa medical formulation composed of a combination of chitin-glucan and simethicone indicated for the symptomatic treatment of gas-related gastrointestinal disorders by combining different mechanisms of action. Aim: To evaluate the efficacy, tolerability, and safety of 4-week GASTRAP® DIRECT treatment in patients with IBS. Methods: In this prospective, multicenter, open-label trial, 120 patients with IBS received three sticks of GASTRAP® DIRECT (1.5 g/d of chitin-glucan and 0.75 mg/d of simethicone) per day for 4 weeks. The primary endpoint was the responder rate, defined as the number of patients whose abdominal pain score decreased by ≥ 30% from baseline to week (W) 4. The analysis was performed using the per-protocol set. Cardinal symptoms, impact of global symptoms on daily life, change in stool consistency, and improvement in defecatory disorders were evaluated. Results: Overall, 100 patients were evaluated. At W4, 67% (95%CI: 57-75) showed improvement in abdominal pain (score: 5.8 ± 2.4 vs 2.9 ± 2.0, P < 0.0001). Similar improvements were observed for bloating [8.0 ± 1.7 vs 4.7 ± 2.9, P < 0.0001; 60% (95%CI: 50-70) responders], abdominal distension [7.2 ± 2.1 vs 4.4 ± 3.1, P < 0.0001; 53% (95%CI: 43-63) responders], and impact of global symptoms on daily life [7.1 ± 2.0 vs 4.6 ± 2.9, P < 0.0001; 54% (95%CI: 44-64) responders]. Stool consistency improved in most patients (90% and 57% for patients with liquid and hard stools, respectively). Overall, 42% of patients with defecatory disorders reported very much/considerable improvements by W2. No severe adverse event occurred, and tolerability was rated "good" or "very good" by 93% of patients. Conclusion: GASTRAP® DIRECT is safe and well tolerated, alleviating IBS symptoms rapidly in 2 weeks. This open-label study suggests that the combination of chitin-glucan and simethicone could be beneficial in patients with IBS.