Si Shen Wan (Four Spirits Pill) sì shén wán · 四神丸

Safety. The classical indication is 五更泄 - diarrhoea that reliably wakes a person before dawn, framed traditionally as depletion of spleen and kidney yang. Anyone reading their own symptoms into that description should know that chronic morning-predominant diarrhoea has a modern differential which includes irritable bowel disease, microscopic colitis, bile acid diarrhoea, coeliac disease, diabetic autonomic neuropathy and thyrotoxicosis, and that colorectal cancer can present simply as a changed bowel habit. Blood in the stool, weight loss, fever or anaemia are not deficiency symptoms to be warmed; they are reasons for investigation. - 补骨脂 (psoralea fruit) is the ingredient with the strongest documented safety signal. It contains psoralens, the furocoumarins used medically in PUVA photochemotherapy, which means photosensitivity is a real effect: people exposed to psoralens burn more readily, and the combination of psoralen with ultraviolet A is photocarcinogenic. Psoralea-containing preparations have also been reported as a cause of drug-induced liver injury, and that is documented well enough that it is not merely a theoretical caution. - 吴茱萸 (evodia fruit) is classed as slightly toxic in traditional sources, and liver injury has been reported in association with evodia-containing products; its alkaloids (evodiamine, rutaecarpine) affect drug-metabolising enzymes in preclinical work, so the interaction question is open rather than settled. - 五味子 (schisandra fruit) carries the most practically useful interaction note in the formula: it inhibits CYP3A4 and has been shown to raise blood levels of tacrolimus and ciclosporin, which matters for transplant recipients, and this is documented rather than speculative. - 肉豆蔻 is nutmeg, roasted for this formula; myristicin-containing nutmeg is a recognised cause of poisoning at high intake, with tachycardia, confusion and anticholinergic-type features. - 生姜 and 大枣 at the amounts used here are unremarkable, though jujube is sugar-dense, which is a consideration in diabetes. - The traditional framing of warming depleted yang should not be read as a substitute for a diagnosis: whether this formula changes outcomes in any of the modern conditions listed above has not been established. - Amounts are set by a licensed practitioner and are deliberately not given here.