Rongtong Dictionary · Single Herbs

Licorice Root (Gancao): Textual History, the “Chief Minister” of Herbs, Chemistry, and the Limits of the Evidence

Published and reviewed 2026-07-08

Licorice is no mere sweetener-in-a-supporting-role. It is a superior-class drug that Tao Hongjing honoured as guolao — the “chief minister” and “king of herbs” — and that appears in roughly half of Zhang Zhongjing's two-hundred-odd formulas. Its “harmonizing” of other drugs is a formulation function, not a boundless safety guarantee; its chief compound, glycyrrhizin, is both the source of its sweetness and pharmacology and the reason overuse can cause pseudoaldosteronism.

1. Names and origins: “sweet herb,” “honey herb,” and the “chief minister”

Licorice enters the record in the Shennong Bencao Jing, ranked superior and named for its sweetness (“beautiful herb,” “honey-sweet”), credited with dispelling cold-heat pathogens, strengthening sinews and flesh, and resolving toxins; the even earlier Erya already mentions it. In the Northern and Southern dynasties Tao Hongjing gave it an enduring honorific — guolao, “chief minister” — explaining that it is “the master of all drugs, rarely absent from classical formulas… though not the sovereign, it is revered by the sovereign, and so it can harmonize the mineral and herbal drugs and resolve their toxins.” Li Shizhen later called it “the good chancellor among drugs.”

Its story is trans-civilizational: licorice appears in the Code of Hammurabi (~2100 BCE), was stored in Egyptian tombs three millennia ago, and was prized by Greeks and Romans as a cough-and-throat remedy. A humble sweet root threads several thousand years of pharmacy, East and West.

2. Source and authenticity: three species and “nine of ten formulas”

Licorice is among China's most-used bulk drugs — a saying runs that “nine of ten formulas contain licorice,” and its prescription rate approaches 80%, usually as an assistant/envoy that harmonizes. The Chinese Pharmacopoeia admits three legume species: Glycyrrhiza uralensis, G. inflata, and G. glabra, dug in spring and autumn, with Inner Mongolia and Ningxia yielding premium material.

The pharmacopoeia assays liquiritin and glycyrrhizic acid as markers. Processing divides the drug so sharply that raw and honey-fried licorice hold separate monographs: raw licorice clears heat, resolves toxin, and relaxes spasm; honey-fried licorice tonifies the middle and restores the pulse. “Raw to unblock, fried to tonify” is the key to reading any licorice product.

3. Actions and combination: why “classical formulas are rarely without it”

Licorice is sweet and neutral, entering the heart, lung, spleen, and stomach; its actions are tonifying spleen-qi, clearing heat and resolving toxin, transforming phlegm and stopping cough, relaxing spasm and pain, and — uniquely — harmonizing the other drugs of a formula.

A Qing commentary captures it: of Zhang Zhongjing's ~200 formulas, nearly 100 use licorice. It keeps the dispersing formulas (mahuang, guizhi) from over-dispersing, the purging ones (the Chengqi group) from over-purging, the warming ones (Sini, Wuzhuyu) from over-drying, and the cooling ones (Baihu, Zhuye Shigao) from over-chilling — “without licorice mediating between them, each would rush off and not return.” Paired with gypsum and anemarrhena it guards the stomach against cold; with aconite and dried ginger it guards yin against dryness; with rhubarb and mirabilite it gentles a harsh purge. It is the buffer of the formulary — the “king of herbs” by function, not flattery.

4. How the physicians used it: from Zhang Zhongjing's sovereign licorice to Zhi Gancao Tang

Though usually an assistant, licorice sometimes reigns. Zhang Zhongjing's Gancao Tang, Gancao–Ganjiang Tang, and Shaoyao–Gancao Tang make it principal; the last pairs licorice with peony to “relax spasm and pain,” the ancestor of later antispasmodic formulas. The Chengqi purgatives and the Xiexin (“drain the heart”) formulas all pivot on it.

Most famous is Zhi Gancao Tang (Honey-Fried Licorice Decoction, also “Restore the Pulse”), where honey-fried licorice is sovereign alongside ginseng, rehmannia, ophiopogon, donkey-hide gelatin, hemp seed, cinnamon twig, ginger, and jujube, treating “palpitations with a bound or intermittent pulse” — later hailed as a founding yin-nourishing formula. Tellingly, Zhang's original “zhi” licorice was dry-fried, not the honey-fried slice of today — a processing drift that reminds the reader that a shared name need not mean an identical drug.

5. Chemistry and pharmacology: glycyrrhizin and pseudoaldosteronism

Licorice's core compound is the triterpenoid saponin glycyrrhizic acid (aglycone: glycyrrhetinic acid), alongside flavonoids (liquiritin, liquiritigenin, isoliquiritin). Glycyrrhizin is far sweeter than sucrose — hence the “sweet herb” — and is a pharmacopoeial marker.

Preclinical studies attribute anti-inflammatory, antioxidant, hepatoprotective (e.g., effects on carbon-tetrachloride-induced liver fibrosis via TGF-β1 inhibition), and antiviral activities to glycyrrhizin/glycyrrhetinic acid and licorice flavonoids, and glycyrrhizin preparations are used in some liver conditions. Two cautions: most mechanisms are in vitro/animal and are not human efficacy; and glycyrrhizin is simultaneously licorice's chief hazard — it inhibits 11β-hydroxysteroid dehydrogenase, producing pseudoaldosteronism with hypertension, hypokalemia, and edema. NCCIH notes that high-quality evidence is insufficient to clearly support licorice for any health condition.

6. From sliced root to product: compound licorice tablets, glycyrrhizin drugs, and DGL

Licorice's product range is instructive. Traditionally there are raw and honey-fried slices and countless compound formulas; in modern practice, compound licorice tablets (containing licorice fluid extract) were a common antitussive-expectorant, and glycyrrhizin drugs (diammonium glycyrrhizinate, magnesium isoglycyrrhizinate) are used in some liver diseases. Internationally there is also deglycyrrhizinated licorice (DGL), deliberately stripped of glycyrrhizin to reduce blood-pressure and potassium risk, mostly for digestive complaints.

Key points: DGL and whole licorice are not equivalent in composition or risk, and their data are not interchangeable; glycyrrhizin-containing products carry explicit electrolyte and blood-pressure monitoring needs; and licorice used as a food sweetener/flavour differs in context and dose from medicinal use. Any prolonged or larger-dose use warrants professional assessment.

7. Dose, processing, and pharmacopoeial use (for professional reference)

The Chinese Pharmacopoeia gives a usual decoction dose of 2–10 g. Raw versus honey-fried differ in emphasis (raw: clear heat, resolve toxin, relax spasm; fried: tonify the middle, restore the pulse), and the choice follows the treatment strategy. Classical incompatibilities apply: licorice should not be combined with euphorbia (jing-daji), kansui, genkwa, or sargassum. Given glycyrrhizin risk, prolonged high-dose use warrants special caution. The dose range is given to explain the standard, not as individualized advice.

8. Safety boundaries and interactions

Licorice's foremost hazard is glycyrrhizin: excess or prolonged use can cause pseudoaldosteronism — hypertension, hypokalemia, edema, even arrhythmia — with special risk in hypertension, heart, kidney, or potassium disorders and pregnancy. It can interact with diuretics, cardiac glycosides (digoxin), antihypertensives, and corticosteroids. NCCIH notes many U.S. “licorice” products are actually anise-flavoured and contain no real licorice, so labels must be read carefully. Stop and seek care for rising blood pressure, weakness, muscle fatigue, or palpitations, and disclose all licorice-containing herbs, formulas, and supplements at clinical visits.

9. How to judge whether a claim about licorice is credible

• Does it distinguish plant (three species) — raw/honey-fried slice — glycyrrhizin drug — DGL — food sweetener?
• Does it separate the traditional “harmonizing” function from modern clinical evidence?
• Does it state whether studies are in vitro/animal or human, with type, comparator, sample size, and limits?
• Does it flag glycyrrhizin's blood-pressure and potassium risks and special-population boundaries?
• Does it note interactions (diuretics, digoxin, antihypertensives, steroids) and classical incompatibilities?

Educational content only. It does not provide a diagnosis, prescription, or individualized treatment recommendation. The pharmacopoeial dose range is given to explain the standard, not as a basis for self-medication. Seek qualified care for persistent or urgent symptoms.