Pyrrosia, a genus of ferns used in Traditional Chinese Medicine (TCM), is primarily known for its use in clearing heat, promoting urination, and relieving symptoms associated with urinary tract infections or kidney stones. In TCM, "blood poisoning" is not a direct biomedical diagnosis but may refer to various conditions characterized by systemic infection or "heat toxin" in the blood, such as sepsis or severe infections. Pyrrosia (often as Pyrrosia lingua, known as Shi Wei) is occasionally included in herbal formulations aimed at "clearing heat" or "detoxifying the blood," based on traditional concepts rather than modern medical understanding. There is very limited scientific research directly linking Pyrrosia to the treatment of sepsis or blood poisoning as defined in Western medicine. Studies on Pyrrosia have mostly focused on its diuretic, anti-inflammatory, and antioxidant properties. Historical texts and pharmacopeias may mention its use in combination with other herbs for conditions involving systemic inflammation or infection, but these references are rooted in traditional practices rather than clinical trials or biomedical evidence. In summary, the use of Pyrrosia for "blood poisoning" is supported by traditional practices and TCM theory, with little to no direct scientific validation for this specific indication. The evidence rating is low due to a lack of robust clinical or preclinical studies for this use.