Stachytarpheta cayennensis, commonly known as blue porterweed, has a history of use in traditional medicine across various cultures, particularly in the Caribbean, Central, and South America. In traditional herbal medicine, it has been employed for a wide range of ailments, including as a diuretic and for the treatment of kidney ailments and urinary tract infections. Folk practitioners sometimes prepare infusions or decoctions of the leaves or aerial parts to "cleanse" the kidneys or support urinary health. However, scientific validation for its use specifically in treating kidney infections (pyelonephritis) is limited. Most available studies focus on its anti-inflammatory, antioxidant, or general antimicrobial properties, with in vitro and animal model data suggesting some potential activity, but not specifically in the context of kidney infections. There are no robust clinical trials or detailed pharmacological studies that directly assess its efficacy or safety for kidney infections in humans. Therefore, the justification for using Stachytarpheta cayennensis in this context is based on traditional practices rather than established scientific evidence. The evidence rating is moderate (2/5), reflecting the presence of traditional usage and some relevant—but indirect—phytochemical or pharmacological findings, but a lack of direct clinical evidence.