Phellodendron, also known as Huang Bai or Amur cork tree, is a traditional herb in Chinese medicine. Its use for gastrointestinal complaints, including symptoms similar to Irritable Bowel Syndrome (IBS), is rooted in historical practices. Traditionally, Phellodendron bark has been used for its purported anti-inflammatory and antimicrobial properties, often as part of multi-herb formulas such as Huang Lian Jie Du Tang, prescribed for "damp-heat" conditions affecting the digestive tract. While there are animal studies and limited in vitro research suggesting that Phellodendron extracts may modulate inflammatory pathways or gut microbiota, robust clinical evidence in humans for IBS specifically is lacking.

Few, if any, well-designed clinical trials have directly assessed Phellodendron as a monotherapy for IBS. Most available evidence supporting its use comes from traditional usage and anecdotal reports rather than rigorous scientific validation. The rating of 2 reflects this reliance on tradition with some suggestive, but not conclusive, preclinical support. As with many traditional remedies, efficacy and safety for IBS patients have not been firmly established by modern standards. Individuals considering Phellodendron for IBS should consult a healthcare professional, especially due to the lack of high-quality evidence and potential for herb-drug interactions.