Spanish Needle (Bidens pilosa) has a long history of use in traditional medicine in various parts of the world, including Africa, Asia, and the Americas. In these traditional systems, the plant is used for a range of ailments, including infections and inflammation. Its use for kidney infections (pyelonephritis) is documented in some ethnobotanical sources, where decoctions or infusions of the leaves or whole plant are consumed to "cleanse" or "support" the kidneys and urinary tract. However, the evidence supporting this use is primarily anecdotal and based on historical or cultural practices rather than rigorous clinical research.

Scientifically, Bidens pilosa is known to possess antimicrobial, anti-inflammatory, and antioxidant properties, as demonstrated in laboratory studies. Some studies have shown that extracts of the plant can inhibit the growth of certain bacteria, which may be relevant to urinary tract infections. However, there are no controlled clinical trials or robust scientific studies specifically addressing the efficacy or safety of Spanish Needle for treating kidney infections in humans. As such, its use for this condition is considered to be supported by tradition rather than by clinical evidence, and the overall quality of evidence is low.