Palo Azul (Eysenhardtia polystachya), also known as kidneywood, has a long-standing tradition of use in Mexican and Central American folk medicine for urinary tract and kidney-related conditions, including bladder infections (cystitis). The bark and wood are commonly prepared as a tea, believed to act as a diuretic, promoting increased urine flow and, thus, helping to "flush out" the urinary tract. This traditional use is largely anecdotal, with historical records and ethnobotanical surveys documenting its popularity for such purposes among local populations.

However, scientific validation of Palo Azul’s efficacy for treating bladder infections is very limited. Only a handful of laboratory studies have explored its potential antimicrobial or anti-inflammatory properties, and these have generally been preliminary, using extracts in vitro (outside the body) or in animal models. There are no well-conducted human clinical trials evaluating its effectiveness or safety for bladder infections. Thus, while its use is justified by tradition and historical practice, the current scientific evidence to support these uses is minimal, and authoritative health organizations do not endorse it as a treatment for bladder infection.