en Gastroentrology Gastroentrology Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background:</span></i></b><b> </b>Irritable bowel syndrome (IBS) is the most common disorder of the gastrointestinal system. The study aimed to determine the effect of Mesalazine prescription on patients&#39; symptoms and level of fecal calprotectin in patients with IBS with predominant diarrhea and high fecal calprotectin.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> We conducted a double-blinded randomized clinical trial with 90 patients aged 18 to 45. These patients were selected from referrals to the gastroenterology clinic. They were evenly divided into two groups: the Mesalazine group, with an average age of 35.4, and the placebo group, with an average age of 36. The patients in both groups were then monitored for 8 weeks. There were no differences in the distribution of sexes between the two groups.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> In comparison between before and after Mesalazine therapy in our patients marked a statistically significant effect on the quality-of-life variables (p<0.05), patient&rsquo;s level of pain (p<0.05), abdominal distension (p<0.05), and calprotectin level (p<0.05) compared to before Mesalazine in patients studied, which showed the effectiveness of this treatment. However, its effect on stool form was not significant (P=0.11).</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion:</span></i></b><b> </b>Comparing the two groups after the intervention, the quality of life in patients treated with Mesalazine was significantly higher than in patients of the placebo group. The number of defecations in patients treated with Mesalazine was significantly lower than in patients of placebo groups. Abdominal distention and calprotectin levels were significantly lower in these patients than in patients of the placebo group.</span></span></span><br> &nbsp; Abdominal Pain, Calprotectin, Inflammatory Cells, Irritable Bowel Syndrome, Mesalazine. 667 673 http://caspjim.com/browse.php?a_code=A-10-3414-1&slc_lang=en&sid=1 Mohammad Hossein Somi soomi19990@gmail.com 100319475328460054598 100319475328460054598 No Liver and Gastrointestinal Diseases Research Center of Tabriz University of Medical Sciences, Tabriz, Iran Masood Faghih Dinevari dinevary1360@gmail.com 100319475328460054599 100319475328460054599 No Liver and Gastrointestinal Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran. Behnam Sajedi sajedibehnam9@gmail.com 100319475328460054600 100319475328460054600 Yes Liver and Gastrointestinal Diseases Research Center, Ardabil University of Medical Sciences, Ardabil, Iran Mehdi Rasolimanesh rasooliii911@gmail.com 100319475328460054601 100319475328460054601 No Liver and Gastrointestinal Diseases Research Center, Kashan University of Medical Sciences, Kashan, Iran Faraz Mahdizadeh farazm20@gmail.com 100319475328460054602 100319475328460054602 No Student General Practitioner, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran Farzad Heydari farzadheidari1379@gmail.com 100319475328460054603 100319475328460054603 No Student General Practitioner, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran