Halloysitum Rubrum — a clay mineral drug, predominantly the hydrated aluminium silicate halloysite with iron oxides giving the red colour; a processed red kaolin-type earth from natural deposits.
Nature and flavour. Sweet, sour and astringent, warm. Stomach and Large Intestine systems.
A clay used as a medicine, which is a category that surprises people and that deserves a plain description. The sources record it for chronic diarrhoea and for the traditional picture of laxity with bleeding from the lower digestive tract, and externally for sores that will not close and for weeping, non-healing lesions. Modern kaolin has a long history of exactly the same internal use in Western domestic practice, and the mechanism assumed for both is physical — adsorptive, protective, bulking — rather than pharmacological. The human evidence for the traditional indications is limited and is not established, and the external use is better supported by tradition than by trials.
性味归经。甘、酸、涩，温。归胃、大肠经。
以黏土入药——这一类常让人意外，值得如实说明。文献记载其用于久泻，以及古籍所称滑脱不禁伴下消化道出血的情形；外用于久不收口的疮疡与渗液不愈的创面。现代高岭土在西方家常用药里有着几乎相同的内服使用史，两者被假定的机制都是物理性的——吸附、保护、增加体积——而非药理作用。传统用途的人体证据有限，尚未被证实；外用的支持更多来自传统而非试验。
它是矿物，而矿物的风险就是一起从地里带出来的东西。天然黏土矿层可伴生铅、砷、镉等重金属以及结晶硅；长期内服属累积性暴露，不应长期服用。只能使用经检验的材料，来源不明的散装矿物粉是这里的主要风险。黏土是吸附剂，会降低其它口服药的吸收——必须与任何其它药物间隔数小时；正在使用地高辛这类窄治疗窗药物或任何必需药物者，应先问药师。便秘、大便干结以及存在梗阻可能时，涩肠是错的方向；孕期与儿童不宜。外用相对安全，但材料仍须洁净。