Fuling Rongyan Tang (Poria, Atractylodes and Rock Salt Decoction) fú líng róng yán tāng · 茯苓戎盐汤

Safety. Three ingredients, and the third is salt. That deserves to be said without softening, because it is the thing about this formula that a modern reader will notice and that the classical line never remarks upon. 戎盐 is rock salt, also named 大青盐, sodium chloride. In a formula whose presenting complaint is 小便不利 — scanty or difficult urine — a sodium load is not an excipient-level matter. Heart failure, hypertension, chronic kidney disease and cirrhosis are precisely the conditions in which both scanty urine and visible fluid retention are common, they are precisely the conditions in which sodium retention makes the picture worse, and they are precisely the conditions in which someone is most likely to be looking for help with water. This library records the tension as a feature of the formula rather than as a reason to argue with a text two thousand years old. It also records that modern instructions for such conditions routinely set a sodium ceiling measured in grams per day, which is an amount a person can reach without noticing. The rest of the entry is shorter. The line assigns this formula the same indication it has just assigned to two others, with almost no overlap in ingredients and no rule for choosing. Three options, one sentence, no discriminator: this library notes the absence and supplies nothing. And 小便不利 itself resolves into several different things that now have separate names and separate first tests. Too little urine is oliguria, the earliest sign of acute kidney injury, urgent because obstruction — stone, prostate, stricture, tumour, catheter — is reversible only while it is still being sought, and because in an older person retention can present as restlessness or new confusion rather than as pain. Difficulty emptying divides into obstructive and non-obstructive causes and is sorted today with a post-void residual and an ultrasound. Frequency, urgency and burning answer to urinary tract infection, interstitial cystitis, stone and urethral syndrome, and again, in an older person, infection may present without fever. Two materia notes. 茯苓 is a fungal sclerotium that grows on pine roots; it is a wood-decaying fungus, and it is not 土茯苓, which is a Smilax root and an entirely different plant. 白术 is Atractylodes macrocephala; classical texts often did not separate it from 苍术, and later practice did — this library records the split without adjudicating the older usage. White atractylodes is discussed in modern pharmacological literature in relation to fluid handling, and this library makes no clinical claim on the basis of that literature. Reliable safety data for pregnancy and breastfeeding are lacking, and this library does not suggest use in either. Chinese-language reports of formulas of this class are small and methodologically limited; this library records that they exist, not that benefit has been established.