Euphorbia pekinensis, known as "Peking Spurge," is a traditional Chinese medicinal herb. Its use for anal fistula and fissure is primarily grounded in traditional practice rather than robust scientific evidence. In Traditional Chinese Medicine (TCM), Euphorbia pekinensis is considered to have strong purgative and detoxifying properties and is used to "dispel water accumulation" and "remove toxins," which historically made it a candidate for treating various skin and soft tissue conditions, including suppurative diseases such as anal fistula and fissures. The herb is typically included in topical or oral formulations aimed at reducing inflammation, promoting discharge of pus, and facilitating healing of chronic sores or fistulas.

However, modern scientific validation for these uses is limited. There are only sporadic pharmacological reports suggesting anti-inflammatory or cytotoxic activities of extracts from the plant, but there are no high-quality clinical studies directly supporting its effectiveness for anal fistula or fissure. Moreover, Euphorbia pekinensis is known to be toxic, especially when used internally, which limits its therapeutic window. In summary, the rationale for its use in anal fistula or fissure is primarily based on historical and traditional use in TCM, with little current scientific data to confirm efficacy or safety for these specific conditions.