Hydrangea (Hydrangea arborescens) has a long history of use in traditional herbal medicine, particularly in North America, as a remedy for urinary tract conditions, including urinary tract infections (UTIs), kidney stones, and bladder inflammation. Native American tribes and early American herbalists commonly used the root and rhizome as a diuretic and to "cleanse" the urinary tract, believing it could help flush out irritants and soothe the lining of the bladder and urethra.

Despite this traditional use, there is very limited scientific evidence supporting Hydrangea's effectiveness for treating or preventing UTIs. Most of the available information comes from historical texts and anecdotal reports. Modern research on Hydrangea has primarily focused on its potential anti-inflammatory and antioxidant properties, but studies are mostly limited to in vitro (test tube) or animal models. There are no robust clinical trials in humans demonstrating its efficacy against UTIs specifically.

In summary, while Hydrangea is traditionally used for urinary tract health, its use for UTIs is not validated by modern scientific research, and the overall quality of evidence is low. Anyone considering herbal remedies for UTIs should consult a healthcare professional, as untreated or improperly treated UTIs can lead to serious complications.