Shu Zao Yin Zi (Dredging and Channelling Drink) shū záo yǐn zǐ · 疏凿饮子

Safety. Shu Zao Yin Zi comes from the Jisheng Fang, and the name is literal: dredging and channelling, the work the classical tradition attributes to Yu when he opened the nine rivers. The formula moves on two fronts at once. Notopterygium, large-leaf gentian and ginger peel release the exterior, while the diuretics and the purgatives drain downward. That double action is why the classical formularies group it apart from the purely downward prescriptions, and it is also why this entry has to say more about the identity of its ingredients than most entries do. Pokeweed root is toxic. Shang lu is Phytolacca, and the standing confusion between its root and roots sold as ginseng, or as so-called native ginseng, is a real and repeated cause of poisoning rather than a theoretical one; the root has also been mistaken for horseradish and for other edible roots. American pokeweed is naturalised in China and is the species named in a number of reported poisonings. The saponins it contains produce burning of the mouth and throat, vomiting and diarrhoea, and at larger exposures neurological and cardiovascular effects. The mu tong in the formula is a second problem of identity, and the more serious one. The name covers several different plants. Guan mu tong is the stem of Aristolochia manshuriensis and contains aristolochic acid, the cause of aristolochic acid nephropathy and of carcinoma of the urinary tract; it must never appear in any preparation. What is legitimate today is the akebia stem of the Akebia species, or the clematis stem sold as chuan mu tong. Anyone reading a list of ingredients from a classical formula needs to know that the name alone does not tell you which plant was in the bowl. Two smaller confusions belong in the same paragraph. Chi xiao dou, the adzuki bean of this formula, is not the decorative red-and-black seed sold as a love pea, Abrus precatorius, whose seeds contain abrin and are among the most poisonous seeds known; the two have been confused in markets. Jiao mu is the seed of the Sichuan pepper, not the pungent husk that goes into the kitchen. The rest of the list carries its ordinary burdens. Areca seed brings arecoline and the carcinogenicity finding attached to areca. Alisma is a diuretic with renal findings reported in animal work at high exposure, and with a potassium-losing effect that matters when a person is also taking diuretics, digoxin, corticosteroids or stimulant laxatives. Poria skin is the outer layer of a fungal sclerotium, not a plant root. And the presentation again belongs to modern diagnosis. Generalised swelling with laboured breathing and reduced urine output is cardiac, hepatic, renal, protein-losing or drug-induced until shown otherwise; in an older person who cannot lie flat it may be acute decompensated heart failure, which is managed in hours rather than in courses. This library records the composition and stops there: no amounts, no preparation, no instructions, no claim of effect.