Gan Cao Tang
Star甘草汤 (Licorice Decoction)
Source: Shang Han Lun — Zhang Zhong-Jing (Eastern Han, c. 220)
Last updated October 20, 2026
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Description
Gan Cao Tang (Licorice Decoction) is the formula given in Line 311 of the Shang Han Lun for sore throat in lesser yīn disease of two or three days (lesser yīn visiting heat); Platycodon Decoction is given if it does not resolve. The commentary notes that the licorice is used raw, to clear heat and resolve toxin.
Source: Mitchell C, Feng Y, Wiseman N. Shang Han Lun: On Cold Damage, Translation & Commentaries. Paradigm Publications, 1999, pp. 517–518.
Composition
Liquorice — estimated at the Chinese Pharmacopoeia's minimum content: about 563 mg of glycyrrhizic acid a day (Gan Cao 31.25 g × 1.8 %). The EU Scientific Committee on Food considers 100 mg/day an upper limit for regular intake that protects most people. The estimate assumes all of it passes into what is taken, uses the pharmacopoeia's dry-weight minimum, and takes the amounts as one day's dose.
Sources
Sources: Chinese Pharmacopoeia 2020, 甘草 and 炙甘草, assay (glycyrrhizic acid not less than 1.8 % in the dispensed slices and 1.0 % in honey-fried liquorice, by dry weight). EU Scientific Committee on Food, Opinion on glycyrrhizinic acid and its ammonium salt, SCF/CS/ADD/EDUL/225 Final, 2003. The Committee notes this limit may not protect people with high blood pressure, electrolyte or fluid-balance disorders, slow gut transit, or reduced 11β-HSD2 activity.
- 《中华人民共和国药典》2020年版一部 — 甘草, 饮片 甘草片【含量测定】甘草酸 不得少于1.8%（按干燥品计算） (opens in a new tab)
- 《中华人民共和国药典》2020年版一部 — 炙甘草【含量测定】甘草酸 不得少于1.0%（按干燥品计算） (opens in a new tab)
- EU Scientific Committee on Food, Opinion on glycyrrhizinic acid and its ammonium salt, SCF/CS/ADD/EDUL/225 Final (10 April 2003) (opens in a new tab)
- EMA/HMPC/108399/2024 — European Union herbal monograph on Glycyrrhiza glabra L.; Glycyrrhiza inflata Bat.; Glycyrrhiza uralensis Fisch., radix, §4.9 Overdose (opens in a new tab)
| Herb | Amount | % | Role | Function |
|---|---|---|---|---|
|
Gan Cao
as printed: 甘草二两 (2 liang; not marked mix-fried, used raw per the commentary on p. 518); 31.25 g at 1 liang = 15.625 g (p. 64)
|
31.25g | 100% | — |
Energetics dose-weighted
The formula's overall nature, taste balance and channel reach, weighted by each herb's dose. Classical formulas often pair warm and cool herbs on purpose, so a net figure summarises the mix — it doesn't describe every herb in it.
Nature
Net neutral (0.00)
From 100% of the weighed grams.
Grams by band: neutral 100%.
Taste
- sweet 100%
From 100% of the weighed grams.
Channels reached
- Lung 100%
- Stomach 100%
- Spleen 100%
- Heart 100%
Share of the grams entering each channel, from 100% of the weighed grams.
Dose-weighted from each herb's recorded nature, taste and channels (missing values are left out, never counted as neutral). It describes the composition — it is not a recommendation.
Preparation
[For] the above one ingredient use three shēng of water. Boil to get one and a half shēng and remove the dregs. Take seven gě warm, two times a day. (Mitchell, Feng & Wiseman 1999, pp. 517–518, Line 311)
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Match score combines dosage-weighted composition (cosine, 70%) with shared-herb overlap (Jaccard, 30%).
Traditional formula information is for educational purposes only. Herbal formulas should be prescribed by a qualified practitioner — dosages and combinations are individualized and can interact with medications.
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