Nettle (Urtica dioica), commonly known as stinging nettle, has a long history of traditional use in supporting urinary tract health, including the bladder. Traditional European and herbal medicine systems have utilized nettle for its diuretic properties, meaning it helps promote urine flow and reduce fluid retention. This action was believed to "cleanse" the urinary tract and support overall bladder health. Specifically, nettle leaf and root have been used in folk medicine to alleviate symptoms of urinary tract discomfort, irritation, and mild lower urinary tract symptoms, especially in men with benign prostatic hyperplasia (BPH), which can impact bladder function.

The scientific evidence for nettle’s effects on the bladder itself is limited. Most modern research has focused on nettle root and its benefits for prostate health, which may indirectly influence bladder health by reducing symptoms like urinary frequency or urgency associated with BPH. Some studies suggest that nettle root may inhibit certain inflammatory pathways or enzymes involved in prostate enlargement, but direct effects on the bladder are not well established. Nettle leaf, on the other hand, is mainly studied for its general anti-inflammatory and diuretic effects rather than specific bladder-supporting actions.

In summary, the use of nettle to support the bladder is primarily based on traditional herbal practices, with only preliminary or indirect scientific support. The evidence rating is moderate (2) due to historical use and some related research, but direct, high-quality clinical trials for bladder support are lacking.