Lao Xinglin 老杏林
Gan Cao (Licorice) illustration

The Herb Cabinet 本草

甘草 gān cǎo

Glycyrrhiza uralensis · licorice root

Neutral Sweet All twelve channels Qi tonic 补气

“The peacemaker of the cabinet. It sweetens, softens, and keeps the other herbs from quarreling — though even peacemakers have limits.” — Lao Xinglin

What the tradition says

No herb appears in more classical formulas than gan cao, and its nickname — the "old gentleman of the nation" (国老) — tells you why: it harmonizes. Sweet and neutral, said to enter all twelve channels, licorice moderates harsh herbs, unifies a prescription into one medicine, tonifies the spleen, moistens the lung for cough, eases spasmodic pain, and clears fire toxin from sores and throats[1]. In most formulas it takes the modest "envoy" seat; the honey-fried form (炙甘草, zhi gan cao) is the warmer, more tonifying preparation[1].

What the research says

For all its ubiquity, the evidence for licorice as a treatment is thin: the NIH finds no condition with clearly supportive high-quality evidence, with preliminary signals for mouth ulcers and post-intubation sore throat[2]. The research that is solid concerns safety — see below.

Where to be careful

This is the important section. Licorice contains glycyrrhizin, which in large amounts or over long periods drives potassium down and blood pressure up — a condition called pseudoaldosteronism that can progress to irregular heartbeat and, rarely, cardiac arrest[2][3]. Risk concentrates in people with hypertension or heart or kidney disease, and rises with dose and duration[3]. Inside classical formulas the doses are small and typically short-term, which is exactly how the tradition used it; licorice teas, candies, and supplements taken daily are the usual source of trouble. Deglycyrrhizinated licorice (DGL) removes the compound at issue.

In the pharmacy

The sweet root of Glycyrrhiza uralensis (or G. glabra), sold raw in yellow slices or honey-fried to a deeper brown. That sweetness is glycyrrhizin itself — some fifty times sweeter than sugar, medicine and hazard in the same molecule.

References

  1. Bensky, Clavey & Stöger, Chinese Herbal Medicine: Materia Medica, 3rd ed., Eastland Press, 2004. ↩
  2. National Center for Complementary and Integrative Health (NIH), "Licorice Root: Usefulness and Safety." https://www.nccih.nih.gov/health/licorice-root ↩
  3. Yoshino T, Shimada S, Homma M, Makino T, Mimura M, Watanabe K. Clinical risk factors of licorice-induced pseudoaldosteronism based on glycyrrhizin-metabolite concentrations: a narrative review. Front Nutr. 2021;8:719197. PMID 34604277. https://pubmed.ncbi.nlm.nih.gov/34604277/ ↩

Under the modern lens

Chemists have catalogued some 558 distinct compounds in gān cǎo. The ones their papers return to most often:

GlycyrrhizinLiquiritinGlabridinGlycyrrhetinic acid

Constituent records from SymMap v2.0 and TCMSP, retrieved August 2026 and checked by hand. A list of what's inside is a map, not a promise — chemistry alone doesn't prove an effect.

Used in formulas

Lao Xinglin seal Reviewed 2026-08-25