Nettle (Urtica dioica) has a long history of traditional use for supporting urinary system health, particularly in Europe. Traditionally, nettle leaf and root have been used as a diuretic ("water pill") to promote the excretion of urine and to help relieve symptoms associated with urinary tract infections (UTIs) and benign prostatic hyperplasia (BPH). Scientific research has begun to validate some of these uses, especially regarding nettle root and its effect on BPH symptoms in men. Several clinical studies and reviews have reported that nettle root extract may help reduce lower urinary tract symptoms associated with BPH, such as urinary frequency, urgency, and nocturia. The mechanism appears to involve anti-inflammatory properties, inhibition of certain enzymes relevant to prostate tissue, and possibly effects on sex hormone-binding globulin (SHBG).

However, while the evidence for nettle root in BPH is promising, it is not robust for all urinary conditions. Evidence supporting nettle leaf as a diuretic is weaker and mainly based on traditional use rather than modern clinical research. Overall, nettle is considered reasonably safe for most people when used appropriately, but more rigorous, large-scale studies are needed to fully confirm its effectiveness across all urinary conditions. Thus, nettle’s use for supporting the urinary system is partially justified by scientific evidence, with the strongest support for its use in BPH.