Plant-Derived Treatments for IBS: Clinical Outcomes, Mechanistic Insights, and Their Position in International Guidelines

Irritable Bowel Syndrome (IBS) affects 4–15% of the global population, and the limited efficacy of existing pharmacologic therapies has driven growing interest in plant-based therapeutic options among both patients and clinicians. A comprehensive assessment of all plant extracts investigated in IBS is therefore essential, given the limited effectiveness of conventional treatments and the increasing interest in complementary approaches. Evidence from recent systematic reviews and meta-analyses consistently indicates that peppermint oil is the most effective botanical agent, particularly for reducing abdominal pain and overall IBS symptom severity. Iberogast (STW-5 and STW-5 II) has also demonstrated clinical improvements across multiple trials, while curcumin shows mechanistic and preliminary clinical potential by modulating several IBS-related pathways. In contrast, extracts such as Curcuma xanthorrhiza, Fumaria officinalis, and various Ayurvedic formulations have not shown significant clinical benefit. Other agents, including Aloe vera, flavonoids, St John’s wort, and ginger, exhibit mixed or inconsistent results, reflecting heterogeneity in study designs and underlying mechanisms. A review of international guidelines reveals that peppermint oil is the only plant-based therapy consistently acknowledged across adult and pediatric recommendations. The aim of this review is to summarize, compare, and critically evaluate all plant extracts studied for the prevention and treatment of IBS, integrating mechanistic pathways, clinical evidence, and current international guideline recommendations to clarify their therapeutic relevance for clinical practice.