Ban Xia Hou Po Tang (Pinellia and Magnolia Bark Decoction) bàn xià hòu pò tāng · 半夏厚朴汤

Safety. The ingredient that must be explained first is 半夏 (pinellia). Raw pinellia tuber is an irritant poison: it contains needle-shaped calcium oxalate raphides and lectins that cause intense burning and swelling of the mouth, tongue and throat, and swelling in that space can threaten the airway. It is never used raw by mouth. Every product on the market uses a processed form - 法半夏, 姜半夏 or 清半夏 - and the processing is the safety measure, not a refinement of flavour. Traditional texts also list pinellia as incompatible with aconite-type herbs (the 十八反 incompatibility), so the two should not be combined in the same preparation. - The classical indication is the sensation described as 咽中如有炙脔 - a lump in the throat that will not swallow away - which later tradition calls 梅核气, plum-pit qi. A persistent sensation of a lump, or actual difficulty swallowing, has structural causes that must be excluded: reflux, thyroid enlargement, oesophageal motility disorders, and tumours among them. This formula is the common reason people present late with a swallowing problem they have been treating as a qi pattern, and that is worth saying directly. - 厚朴 (magnolia bark) contains honokiol and magnolol. Honokiol modulates GABA-A receptors in preclinical work, so additive sedation with alcohol, benzodiazepines or other sedating medicines is plausible; the human evidence for this is limited and is stated as such. Magnolia bark is also one of the botanicals where substitute species turn up in commerce, so knowing which Magnolia was used matters. - 生姜 in the amounts used as food is unremarkable, but concentrated ginger products carry antiplatelet and warfarin cautions, and ginger can aggravate gallstone symptoms in some people. - 紫苏叶 (perilla leaf) is widely eaten as a food herb; allergy within the Lamiaceae (mint) family is the main caution, and perilla seed oil and perilla leaf are different products. - Guidance on pinellia in pregnancy conflicts between sources, and that conflict is a reason not to self-administer rather than a reason to pick a side. - Amounts are set by a licensed practitioner and are deliberately not given here.