Aerva lanata, commonly known as mountain knotgrass or "polpala," has a long-standing history of use in traditional medicine systems, especially in Ayurveda and other South Asian medicinal practices, for supporting urinary tract and bladder health. Traditionally, the whole plant or its decoctions are used as a diuretic, to support urine flow, and to help in the management of urinary stones (urolithiasis). Ethnobotanical surveys and Ayurvedic texts mention its use for alleviating difficulties in urination, reducing burning sensations, and promoting the expulsion of kidney and bladder stones.

Scientific studies supporting these traditional uses are limited but present. In vitro and animal model research indicates that aqueous extracts of Aerva lanata may possess diuretic and anti-urolithiatic activities. Some studies have demonstrated a decrease in stone formation and an increase in urine output in rats, suggesting a possible scientific basis for its traditional use. Phytochemical analyses reveal the presence of alkaloids, flavonoids, and saponins, which might contribute to its observed effects.

However, robust clinical trials in humans are lacking, and most evidence is either anecdotal or preclinical. Thus, while there is a strong tradition of its use for supporting the bladder and urinary tract, with some preliminary scientific validation, the overall strength of evidence remains moderate at best.