Ren Zhi Jia

Ren Zhi Jia (人指甲), also called Unguis Hominis or Ren Jia in classical sources, is the human fingernail used as a traditional Chinese medicinal substance. The keratinous nail clippings are collected, cleaned, soaked in alkaline water, washed, and dried before use, sometimes calcined to a fine ash. Composed chiefly of fibrous keratin, the material is classified in TCM as sweet and salty, neutral, entering the Liver and Lung channels. Classical indications include bleeding from external wounds, sore throat, ear discharge, and difficult labor, where it has been used topically or in small ground or charred doses. Modern practice rarely employs Ren Zhi Jia due to ethical, hygienic, and biosafety concerns surrounding human-derived substances, and it is omitted from most contemporary materia medica.