Longleaf buchu (Agathosma betulina or Agathosma crenulata) has a longstanding traditional use in South African herbal medicine, where it has been employed as a diuretic and for urinary tract ailments, including kidney stones. Indigenous Khoisan peoples and later European colonists used buchu leaves to make infusions believed to promote urinary health. Historical texts from the 19th century document its use as a folk remedy for kidney and bladder complaints, likely due to its perceived ability to increase urine flow and potentially "flush out" stones or gravel.

However, scientific validation for buchu's effectiveness in treating or preventing kidney stones is extremely limited. Modern research has identified certain volatile oils (such as diosphenol) in buchu with mild antiseptic and diuretic properties, but there are no high-quality clinical trials demonstrating efficacy against kidney stones. Most contemporary herbal references mention buchu's use for urinary tract infections rather than for calculi specifically. As such, the evidence for its use in kidney stone support is primarily anecdotal and traditional, rather than evidence-based.