Birch (Betula spp.) has a long history of use in traditional herbal medicine, particularly in Europe and parts of Asia, for supporting urinary tract health and the bladder. Traditionally, birch leaves and bark have been used as a mild diuretic, meaning they promote the production of urine. Folk medicine practitioners have employed birch preparations to help flush out the urinary system, reduce water retention, and sometimes to relieve symptoms of urinary discomfort or inflammation. The diuretic effect is thought to help "cleanse" the bladder and urinary tract, although these claims are based primarily on historical use rather than rigorous scientific validation.

Scientific evidence supporting the use of birch for bladder health is limited. Some laboratory and animal studies suggest that birch leaves contain flavonoids, saponins, and other compounds that may promote diuresis. However, well-controlled clinical trials in humans are lacking, and there is insufficient evidence to firmly establish efficacy for bladder-related conditions. Regulatory bodies such as the European Medicines Agency acknowledge birch leaf’s traditional use for "increasing the amount of urine to achieve flushing of the urinary tract," but stress that these uses are based on longstanding practice rather than scientific proof. Therefore, the use of birch for supporting the bladder is primarily justified by tradition, with only modest evidence from scientific research.