Si Ni San (Four-Ingredient Counterflow Powder) sì nì sǎn · 四逆散

Safety. A short classical formula of four ingredients, and the one most often taken as the base for later liver-coursing variations. It contains licorice, whose glycyrrhizin can raise blood pressure and lower potassium, particularly with potassium-losing diuretics or cardiac glycosides and with prolonged use. Immature bitter orange (枳实) contains synephrine-type amines, which has prompted caution in people with cardiovascular conditions and in those taking stimulant or decongestant medicines; its safety in pregnancy is not established. The traditional indications recorded for this formula come from classical sources rather than from controlled trials, and the modern research mostly concerns the individual ingredients rather than this combination. Despite the similarity of the name, this is a different formula from 四逆汤 (Si Ni Tang), which contains aconite and carries a different risk profile. For pattern differentiation by a licensed practitioner only; amounts are deliberately not given here.