The use of knotweed (commonly referring to Polygonum cuspidatum, also known as Japanese Knotweed) for gall stones is primarily rooted in traditional medicine, particularly within East Asian herbal practices. Traditional Chinese Medicine (TCM) has employed various species of knotweed for their purported ability to "clear heat," "eliminate toxins," and support liver and gallbladder function. In some folk remedies, knotweed preparations have been used to address symptoms associated with gallbladder distress, including gall stones, although it is not a principal herb for this condition in classic TCM texts.

Scientifically, most studies on knotweed focus on its rich content of resveratrol and other polyphenols, which exhibit antioxidant and anti-inflammatory properties. However, there is a lack of direct clinical evidence or robust animal studies demonstrating that knotweed or its extracts can dissolve gall stones or significantly alter their formation. The rationale for its use in gall stones may stem from its general liver-protective effects and its mild choleretic (bile-increasing) activity observed in some experimental settings, but these findings are not specific or substantial enough to support its efficacy for gall stones in humans.

In summary, knotweed’s use for gall stones is based more on historical and traditional usage rather than validated scientific research. At present, the evidence base supporting its effectiveness for this condition is minimal, and it should not be considered a primary or reliable treatment for gall stones.