Irritable bowel syndrome (IBS) and functional dyspepsia (FD) are common functional gastrointestinal disorders with overlapping symptoms. Effectiveness and safety of Menthacarin (Menthacarin® is the active ingredient of the product Carmenthin® [Dr. Willmar Schwabe GmbH & Co. KG, Karlsruhe, Germany]) in FD treatment were already demonstrated. We assessed the effectiveness of Menthacarin in reducing concomitant IBS-associated symptoms in FD patients. A systematic search to identify eligible double-blind, randomized controlled trials (RCTs) investigating Menthacarin in FD patients and focusing on IBS-associated symptoms was performed. Three out of five identified RCTs included a total of 111 eligible subjects, which allowed for summary statistics and inclusion into subgroup analysis for FD patients with IBS-associated symptoms. With pain intensity values decreasing by 50–75% on average during 28 days of treatment in patients with accompanying IBS, the subgroup analysis indicates beneficial treatment effects of Menthacarin that are similar to those found for FD patients in the primary analyses. The reduction of IBS-associated symptoms in FD patients suggests Menthacarin as a treatment option for IBS patients.