Hou Po Wen Zhong Tang (Magnolia Bark Middle-Warming Decoction) hòu pǔ wēn zhōng tāng · 厚朴温中汤

Safety. Hou Po Wen Zhong Tang is recorded in Neiwaishang Bianhuo Lun, the thirteenth-century work of Li Gao (Li Dongyuan), and it is this library's first entry in a category that had been empty until now: warming the middle and moving qi. Every ingredient in it is acrid, warm and drying except fu ling, which drains rather than warms. The classical target is cold-damp with qi stagnation in the spleen and stomach, and the presentation given is fullness and distension in the epigastrium and abdomen, pain, poor appetite and heaviness of the limbs. In the classical account the fullness is the point: it is what happens when cold and damp obstruct the middle and qi has nowhere to go. Fullness is also one of the most dangerous ordinary words in medicine, and this entry has to say why. Abdominal distension and pain that begins suddenly, or is severe, or comes with vomiting, fever, an inability to pass stool or wind, blood in the stool, or a rigid and tender abdomen, belongs in surgical assessment. Appendicitis, cholecystitis, bowel obstruction, perforation, mesenteric ischaemia, ectopic pregnancy and abdominal aortic aneurysm all present with abdominal pain, and a formula that moves the bowels is contraindicated while obstruction has not been excluded. Abdominal pain in pregnancy needs obstetric assessment rather than self-management. Distension that persists has its own list: functional dyspepsia, irritable bowel syndrome, gastroparesis, small intestinal bacterial overgrowth, coeliac disease, ovarian and pancreatic cancer, and ascites from liver or heart failure. What moves a person out of the first group and into investigation is unintentional weight loss, blood in the stool, difficulty swallowing, vomiting, pain that wakes them from sleep, iron-deficiency anaemia, and indigestion beginning for the first time after the age of fifty. This library lists them because a formula for fullness is exactly what a person reaches for while those are being missed. Two ingredients carry most of the specific cautions. Zhi gan cao contains glycyrrhizin, and liquorice taken over time is a well documented cause of apparent mineralocorticoid excess: raised blood pressure, low potassium and oedema. The effect is additive with diuretics and with digoxin, whose toxicity rises as potassium falls. Mu xiang is the root of an Aucklandia (Saussurea costus) species; it is not the same substance as qing mu xiang, which is an Aristolochia species containing aristolochic acid and is no longer used medicinally. The two names differ by a single character, and that distinction is worth restating every time the name appears. Hou po's principal constituents, magnolol and honokiol, have been studied for muscle relaxation and central nervous depression, and there are animal reports of kidney effects at high exposure; this library labels that animal and laboratory evidence because that is what it is. Gan jiang and cao dou kou are acrid and warm, and the whole formula is unsuitable where heat and depleted yin are the picture. Chen pi and hua ju hong are two different substances despite the similar names. A formula this acrid, warm and moving is, in pregnancy, a decision for the person's own clinicians. Research on this formula is largely preclinical. This library makes no claim of efficacy.