Palo Azul (Eysenhardtia polystachya), also known as kidneywood, has a long history of use in traditional Mexican and Central American herbal medicine. Its primary traditional applications include support for urinary tract health, kidney stones, and as a diuretic. Some folk practices extend its use to "purifying" the body, which may loosely include supporting the liver and gallbladder. However, there is little direct documentation in traditional sources specifically citing Palo Azul for the treatment or prevention of gallstones (cholelithiasis). Most references associate it with kidney stones, not gallstones, and the mechanisms for these two conditions are quite different.

Regarding scientific evidence, there are currently no high-quality clinical trials or robust pharmacological studies supporting the efficacy of Palo Azul for gallstones. The available studies focus on its antioxidant and anti-inflammatory properties, and its possible effect as a mild diuretic. These properties could theoretically support general detoxification, but there is no direct evidence they affect gallstone formation or dissolution.

In summary, while Palo Azul is traditionally used for urinary and kidney health, its use for gallstones is either extrapolated or anecdotal. The evidence for its efficacy in treating or preventing gallstones is minimal, and there is no substantial scientific validation for this particular use.