七情合和

The "seven emotions" of herb combination — better translated as the seven modes of interaction — denote the seven possible relationships between two herbs used together. The category appears already in the earliest extant Chinese pharmacopeia, the Divine Husbandman's Classic of Materia Medica (《神農本草經》, Shén Nóng Běn Cǎo Jīng). The seven cover the entire range from full synergy to outright antagonism, and are the basic ruleset for safe and effective formula construction. Mastery of them is the precondition of any responsible prescription.

Despite the name, the "seven emotions" of herb combination have nothing to do with the seven emotions of human psychology that share the term. Here "emotion" carries its older meaning of "mode of relation" or "disposition between two parties."

Single use (单行, dān xíng) — the herb is effective by itself and needs no companion. The classic example is the lone-ginseng decoction, in which ginseng alone is used to rescue a patient in collapse.

Mutual reinforcement (相须, xiāng xū) — two herbs of similar action used together produce a notably amplified effect. Gypsum (Shí Gāo) paired with anemarrhena (Zhī Mǔ) clears qi-level heat far more powerfully than either alone; rhubarb (Dà Huáng) paired with mirabilite (Máng Xiāo) purges accumulated heat from the bowels with combined force.

Mutual assistance (相使, xiāng shǐ) — one herb is primary, the other supports and enhances its effect. Astragalus (Huáng Qí) paired with poria (Fú Líng) is a classic case: poria's percolating action enhances astragalus's qi-tonifying and water-moving functions.

Mutual fear (相畏, xiāng wèi) — one herb's toxicity or side effect is restrained by the other. Raw pinellia (Shēng Bàn Xià) is toxic, but its toxicity is restrained by fresh ginger (Shēng Jiāng); hence the saying that "pinellia fears ginger."

Mutual killing (相杀, xiāng shā) — the complementary phrasing of the same relationship: ginger "kills" the toxicity of pinellia. The terms "fear" and "kill" describe the same pair from each side.

Mutual aversion (相恶, xiāng wù) — one herb diminishes the therapeutic effect of the other. Ginseng "detests" radish seed (Lái Fú Zǐ): the dispersing action of radish seed undermines ginseng's qi-tonifying action.

Mutual opposition (相反, xiāng fǎn) — two herbs combined produce severe toxicity or adverse reaction, and must not be used together. This is the formal basis of the "Eighteen Antagonisms and Nineteen Incompatibilities" (十八反十九畏) memorized by every TCM student. These pairs are strictly avoided in clinical practice.