Realgar (an arsenic sulfide mineral, principally tetra-arsenic tetrasulfide, As4S4)
Nature and flavour. Acrid, warm; classed as strongly toxic. Liver and Large Intestine systems.
A mineral arsenical rather than a plant drug, and the most dangerous item in this batch. Classical texts describe it as counteracting toxin and killing parasites, and record it externally for boils, sores and swellings, for snake and insect bites, and for scabies. It is also the substance behind the realgar wine of the Dragon Boat Festival — a recorded folk custom, and one that food-safety bodies have warned about repeatedly, since that wine is an alcoholic extract of an arsenical mineral. Classical sources also record it taken internally in very small amounts, for worm accumulation and for convulsive disorders. That internal use belongs to the historical record, not to present practice, and contemporary toxicology gives no reading under which it is a household remedy. Heating or burning realgar carries it toward arsenic trioxide, the substance known in Chinese as 砒霜, which is why the older texts already warned against fire and why this drug is never to be heated.
性味归经。辛，温；有大毒。归肝、大肠经。
一味矿物砷药而非植物药，也是本批中最危险的一味。古籍记载攻毒杀虫，外用治痈疽疔疮、肿毒、蛇虫咬伤与疥癣。它也是端午雄黄酒习俗所用的物质 —— 这是有记载的民俗，而食品安全机构已多次警示其风险：该酒本质上是砷矿物的酒精浸出液。古籍亦记载其微量内服，用于虫积与惊痫。内服属于历史记载，不是当代实践；现代毒理学不支持它在任何意义上作为家用药物。雄黄受热或燃烧会向三氧化二砷转化，即中医所称的砒霜，故旧本草早有忌火之说，本品绝不可加热。
文献列为有大毒：本品为砷化物，而砷在体内有蓄积性。任何形式都不作自用，除有资质执业者指导外绝不内服 —— 本页故意不写任何内服份量，因为不存在可以自行掌握的安全量。绝不可加热、燃烧或火煅：加热生成三氧化二砷，吸入其烟气是明确的中毒途径。孕期与哺乳期禁用，儿童忌用，肝、肾疾病患者不宜。不宜大面积、用于破损皮肤或长期反复使用 —— 经皮吸收已有记载。须远离食物、饮水与儿童可触及之处；市场上雄黄与雌黄（As2S3）曾混用，非正规渠道所获者既不能保证品种正确，也不能保证不含其他杂质。任何接触后出现麻木、刺痛、腹痛、呕吐、皮疹或皮肤色素沉着与增厚，都须就医评估；可疑的砷中毒应联系中毒救治机构，而不应等待观察。
1 related entry.