Roots and rhizomesTonifyingRadix et Rhizoma Glycyrrhizae

Gan Cao (Licorice Root)

A practical guide to Gan Cao: what it is, how Traditional Chinese Medicine uses it, the classical formulas it appears in, and who should be careful with it.

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Last reviewed Sep 25, 2026

Quick Facts

Latin NameRadix et Rhizoma Glycyrrhizae
Chinese Name & Pinyin 甘草 · Gan Cao
Medicinal PartRoots and rhizomes
The herbGan Cao is the dried root and rhizome of the three Glycyrrhiza species above. Common forms: raw and honey-fried. Licorice slices and extracts are not the same dose as the decoction piece.
Nature and channelsSweet, neutral. Enters the Heart, Lung, Spleen, and Stomach. Sweetness tonifies, moderates, and harmonizes.
Pharmacopoeia lineTonifies the spleen and boosts qi. Clears heat and resolves toxin. Expels phlegm and stops cough. Relaxes tension and relieves pain. Harmonizes other herbs. Used for spleen-stomach weakness, fatigue, palpitations and shortness of breath, cough with phlegm, cramping pain in the abdomen or limbs, sores, and reducing toxicity or harshness of other drugs.
Pattern cuesSpleen-deficiency fatigue. Palpitations. Cough with phlegm. Cramping pain. Sores and swellings.
In this articleRaw versus honey-fried Gan Cao. How it differs from Da Zao, honey, and Bai Shao. The four incompatible herbs. Why edema and blood pressure matter. Who should skip it.

What Is Gan Cao?

Gan Cao (甘草; Gān Cǎo; Latin: Glycyrrhizae Radix et Rhizoma; English: licorice root / liquorice) is the dried root and rhizome of Glycyrrhiza uralensis Fisch., Glycyrrhiza inflata Bat., or Glycyrrhiza glabra L. In Chinese medicine it is a qi-tonifying herb. It is sweet and neutral, enters the Heart, Lung, Spleen, and Stomach channels, and its core actions are to tonify the spleen and boost qi, clear heat and resolve toxin, expel phlegm and stop cough, relax tension and relieve pain, and harmonize the other herbs in a formula. Older texts call it the “elder statesman” of the materia medica: it softens harsh herbs and moderates toxicity. It is not Western licorice candy. Candy is mostly sugar and does not share the official actions of the decoction piece.

It is used most often for three patterns:

  • Spleen deficiency / insufficient Heart qi — fatigue, palpitations, shortness of breath
  • Cough with phlegm / spasmodic pain — cough from Lung qi not holding, or cramping in the gut or limbs
  • Sores, and harmonizing a formula — boils and toxins, or reducing the harshness of other drugs

Raw Gan Cao leans toward clearing heat, resolving toxin, and expelling phlegm. Honey-fried Gan Cao leans toward tonifying the middle, boosting qi, and restoring the pulse. The usual decoction dose is 2–10 g. Do not combine it with Gan Sui, Jing Da Ji, Hai Zao, or Yuan Hua (the “eighteen incompatibilities”). Damp fullness and edema are a poor match. Long-term or high-dose use can cause edema, higher blood pressure, and low potassium. It is not a root to chew every day as candy.

When qi is weak, cramping hurts, or a formula needs an envoy, Gan Cao’s sweetness tonifies and moderates. That is why it appears in so many prescriptions, including Zhi Gan Cao Tang and Shao Yao Gan Cao Tang. Sweetness can cloy. Middle fullness, phlegm-damp, and a thick greasy coating get worse if more Gan Cao is added.

Gan Cao is not a catch-all for qi deficiency or cough, and it is not a sweet herb to self-dose for months. In damp edema, high blood pressure, or a formula that already contains an incompatible herb, using it alone or in large amounts can generate dampness and raise blood pressure. Raw or honey-fried should be decided by a licensed Chinese medicine practitioner after pattern diagnosis.

Gan Cao Licorice Root

Gan Cao: Materia Medica Profile

Identification & Quality Standard

Radix et Rhizoma Glycyrrhizae

Botanical Origin

The dried root and rhizome of Glycyrrhiza uralensis Fisch.(Fabaceae).

Production Regions

Primarily produced in the Chinese provinces of Inner Mongolia, Shanxi, Gansu, Xinjiang, Ningxia.

Quality Requirements

Superior medicinal material has tight outer skin, reddish-brwon color, firm texture, yellowish-white fractured surface and powdery.

Macroscopic Features

Cylindrical, outer skin unevenly tight. Externally reddish-brown or grayish-brown, with obvious longitudinal wrinkles, grooves, lenticels and loose thin scars of root. Firm texture; fractured surface is slightly fibrous, yellowish-white and powdery. Rhizome surface has scars of bud; fractured surface has pith in the center. faint odor; sweet and distinctive taste. Pieces are angle-cut slices.

Authentic Producing Regions and Quality Identification

  • Key Regions: The best quality traditionally comes from Inner Mongolia, Xinjiang, and Gansu.
  • Appearance: Authentic roots are heavy, solid, and cylindrical with a reddish-brown or grayish-brown exterior. When sliced, the inside is yellowish-white and very powdery/starchy.
  • Taste and Smell: It has a distinct, lingering sweet taste and a mild scent.
  • Quality Check: High-quality pieces are dense with a strong, natural sweetness. Raw slices have a neutral nature, while the honey-fried version is slightly warmer.

Traditional Properties & Historical Lineage

Nature, Flavour & Channel Tropism

Sweet; NeutralHeartLungSpleenStomach

1. Historical Records in Materia Medica

  • Shen Nong Ben Cao Jing: Described it as capable of treating cold and heat evils in the organs, strengthening bones and muscles, and detoxifying the body.
  • Ming Yi Bie Lu: Noted its ability to warm the center, stop coughing and thirst, clear blood pathways, and neutralize the toxicity of other medicines.
  • Ben Cao Gang Mu: Emphasized its role as the ultimate harmonizer in herbal medicine, working like a wise elder to bring balance and peace to the body's internal environment.

2. Evolution of TCM Understanding

Throughout history, different TCM masters have highlighted its versatility:

  • The Nourisher: Some focus on its ability to strongly tonify the Spleen and boost vital energy.
  • The Harmonizer: Others consider it indispensable because it blends perfectly into almost any formula to balance stronger herbs.
  • The Soother: It is also widely trusted for its simple but effective ability to moisten the Lungs and calm acute coughing or wheezing.
  • Takeaway: Gan Cao (Licorice Root) is not a single-purpose cure-all, but a foundational, multi-functional tool that adapts based on how it is combined with other herbs.
Gan Cao Licorice Root

Core Efficacies & Traditional Applications

Traditional Functions

Supplements the spleen, boosts qi, clears heat, resolves toxin, dispels phlegm, relieves cough, relaxes tension, relieves pain, harmonizes the nature of other medicinals.

1. Primary Focus: Tonifying the Spleen and Benefiting Qi

  • Traditional Efficacy: Gan Cao (Licorice Root) is traditionally used to tonify the Spleen and benefit Qi, strengthening the digestive and transport functions of the Spleen and Stomach.
  • Target Symptoms: It is commonly used for Spleen and Stomach weakness, which may present as a sallow complexion, poor appetite, loose stools, fatigue, and lack of energy.
  • Common Combinations: It is often paired with herbs like Dang Shen (Codonopsis Root) and Bai Zhu (Atractylodes Rhizome) to enhance its Spleen-strengthening power.
  • When to Avoid Self-Use: Do not use it on your own if you have "excess" Spleen/Stomach patterns or internal damp-heat accumulation.

2. Secondary Focus: Moistening the Lungs and Stopping Cough

  • Traditional Efficacy: It can effectively moisten the Lungs and relieve coughing.
  • Target Symptoms: Frequently used for coughing and wheezing caused by Lung deficiency.
  • Common Combinations: Often used alongside Jie Geng (Platycodon Root) and Xing Ren (Apricot Seed) to boost its ability to stop coughs and calm wheezing.
  • When to Avoid Self-Use: Use with caution during the early stages of an externally contracted cough (like a fresh cold).

3. Common Single-Herb Pairings

  • Gan Cao and Jie Geng: Gan Cao moistens the Lungs and stops coughing, while Jie Geng opens the Lungs and dispels phlegm. Together, they create a strong synergistic effect for treating coughs with abundant phlegm.
  • Gan Cao and Bai Shao: Gan Cao relaxes spasms and relieves pain, while Bai Shao (White Peony Root) nourishes the blood and softens the Liver to stop pain. This pair is classic for treating rib-side pain due to Liver Qi stagnation. Both pairings require professional TCM diagnosis.
Gan Cao Licorice Root

Modern Research

Modern research offers useful context, but Traditional Chinese Medicine prescribes on whole-pattern diagnosis rather than isolated compounds.

1. Main Chemical Components

Modern science has identified several key compounds, including glycyrrhizin, glycyrrhetinic acid, and various flavonoids.

  • Lab Findings: In test-tube studies, these sweet compounds show anti-inflammatory and anti-allergic properties, while helping to suppress coughs and clear phlegm.
  • Animal Studies: Research on animals suggests it can help regulate the immune system and protect the linings of the digestive and respiratory tracts.

2. Modern Pharmacological Research Directions

Today, scientists are highly focused on the herb's potential for reducing inflammation, modulating immune responses, and its overall protective effects on cellular health. However, much of this is still in the experimental phase, and larger human trials are needed to confirm these specific effects.

3. Limitations of Modern Research

While the science is promising, we must view it through the lens of traditional practice:

  • Animals vs. Humans: Success in a lab or an animal model does not guarantee the same outcome in complex human bodies.
  • Extracts vs. Whole Herbs: Taking an isolated chemical extract (like pure glycyrrhizin) is very different from drinking a traditional, slowly brewed whole-herb decoction.
  • Holistic Synergy: TCM relies on the combined, synergistic effect of all the natural compounds inside Gan Cao (Licorice Root) working together, rather than singling out one specific molecule.
Gan Cao Licorice Root

Comparing Similar Herbs

1. Common Ground: Gan Cao vs. Huang Qi

  • Both Gan Cao (Licorice Root) and Huang Qi (Astragalus Root) are Qi-tonifying herbs used to treat Qi deficiency.
  • Both require careful dosage control, as taking too much can lead to Qi stagnation or bloating. They often appear together in formulas to boost overall energy.

2. Core Differences

  • Nature and Flavor: Gan Cao is sweet and neutral, whereas Huang Qi is sweet and slightly warm.
  • Clinical Focus: Gan Cao excels at harmonizing other herbs, moistening the Lungs, and gently tonifying the Spleen. Huang Qi is much stronger at raising "sunken" Qi and securing the body's exterior to stop excessive sweating.
  • Energy Movement: Gan Cao is mild and stabilizing. Huang Qi has a strong lifting and ascending nature.
  • Target Symptoms: Use Gan Cao for mild Spleen weakness or coughing. Use Huang Qi for severe Qi sinking (like organ prolapse) or spontaneous sweating due to exterior deficiency.
  • Contraindications: Gan Cao should be avoided by those with severe dampness, bloating, or edema. Huang Qi is strictly forbidden for those with excess heat, damp-stagnation, or early-stage skin sores.

3. One-Sentence Summary

Gan Cao is a gentle harmonizer that focuses on tonifying the Spleen and moistening the Lungs; Huang Qi is a powerful lifter that strongly boosts Qi and secures the body's exterior against sweating.

Gan Cao Licorice Root

Classical Formulas Containing Gan Cao

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Formulas vs. Single Herbs

  • Synergy is Key: A formula is a balanced team. The healing power comes from how the herbs interact, so a single herb cannot simply replicate a full formula's effects.
  • Holistic Balance: The exact dosage and combination in a formula affect the entire body. Never try to mix or alter these formulas at home based on internet articles.

Diet & Daily Home Use

1. Home Recipes and Teas

  • Gan Cao Xiao Mai Da Zao Tang (Licorice, Wheat, and Jujube Decoction)
    • Ingredients: 10g Gan Cao (Licorice Root), 30g wheat, 5 jujubes (dates).
    • Method: Boil the three ingredients in water until the wheat is soft and cooked.
    • Best for: Those experiencing emotional restlessness, insomnia, or mental distraction.
    • Note: Do not use if you have internal damp-heat. Limit to 2–3 times a week. Remember, this is a medicinal herb, not a daily food.

2. Decoction and Processing

  • Raw vs. Processed: Raw Gan Cao is better for clearing heat, detoxifying, and dispelling phlegm. Honey-fried Gan Cao (Zhi Gan Cao) is warmer and much stronger at tonifying Spleen Qi.
  • Home Brewing: It does not require special cooking methods and can be boiled regularly with other herbs. Note that different forms (pills, powders, teas) cannot be swapped at a 1:1 dosage ratio.

3. Usage and Dosage

  • Standard Dosage: Traditional prescriptions generally range from 2 to 10 grams. Dietary doses should be much smaller.
  • Usage Cycle: Do not use it continuously for long periods, as it can cause adverse side effects like fluid retention. Special populations must consult a doctor first.
Gan Cao Licorice Root

Contraindications & Safety Warnings

1. Inappropriate Populations

  • Avoid: Individuals with severe dampness, abdominal bloating, or edema (water retention) should not use it.
  • Special Care: Pregnant or nursing women should use it with extreme caution. Children and the elderly need adjusted doses from a doctor.
  • Medical Conditions: Avoid use if you have abnormal kidney or liver function, or if you are allergic to it.

2. Herb-Drug Interactions and Dietary Notes

  • Medication Conflicts: Gan Cao can interact with several Western medications. It may increase the toxicity of cardiac glycosides (heart medications). It can also interfere with the effectiveness of blood pressure and blood sugar medications.
  • Dietary Myths: There is no solid evidence for general "food combining" dangers, but if you are taking prescription drugs, always consult your pharmacist or doctor before adding this herb to your routine.

3. Adverse Reactions and Overdose Risks

  • Overdose Symptoms: Taking too much can cause severe abdominal bloating, loss of appetite, and water retention.
  • Emergency Action: If you experience intense discomfort, allergic reactions, persistent vomiting, shortness of breath, or sudden worsening of symptoms, stop using the herb immediately and seek emergency medical care.

Frequently Asked Questions About Gan Cao

What is Gan Cao? Is it the same as Western licorice or Zhi Gan Cao?
Official Gan Cao (甘草) is the dried root and rhizome of Glycyrrhiza uralensis, G. inflata or G. glabra. The pharmacopoeial name is Glycyrrhizae Radix et Rhizoma; it is nicknamed “National Elder.” G. glabra is one of the three official species, not a different drug. Zhi Gan Cao is the honey-fried slice, a separate monograph stronger to tonify the Spleen and restore the pulse. Western licorice candy and extracts are not official slices.
What are the TCM properties and traditional uses of Gan Cao?
According to the Chinese Pharmacopoeia, Gan Cao is sweet and neutral, enters the Heart, Lung, Spleen and Stomach channels, and acts to tonify the Spleen and benefit Qi, clear heat and resolve toxin, dispel phlegm and stop cough, relax tension and stop pain, and harmonize the other herbs. It is used for Spleen-Stomach weakness, fatigue, palpitations and shortness of breath, cough with phlegm, urgent pain of the abdomen and limbs, sores, and to moderate toxicity and harshness. Sweet and moderating, it is the “National Elder.”
How do raw and honey-fried Gan Cao differ?
Raw Gan Cao leans to clearing heat, resolving toxin and stopping cough—sore throat, sores, Lung-heat cough and drug toxin. Honey-fried Zhi Gan Cao more strongly tonifies the Spleen and Stomach and restores the pulse for weakness, fatigue, fearful throbbing and an intermittent pulse, as in Zhi Gan Cao Tang. Write raw for heat-toxin; write honey-fried to tonify and restore the pulse. Do not write only “Gan Cao.”
What is the usual dosage of Gan Cao?
The pharmacopoeial decoction dose is 2–10 g. As an envoy that harmonizes, 3–6 g is common; relaxing spasm or restoring the pulse may sit higher, still for a short course. It is not a long-term high-dose “sweet tea.” Even small amounts in hypertension, edema or low potassium need monitoring. Topically a suitable amount.
What are the contraindications? Can it be used in pregnancy?
Do not combine with Sargassum, Peking and red euphorbia, kansui or genkwa (the Eighteen Incompatibilities). Use caution in damp fullness, vomiting and edema. Long high doses can retain sodium and water, raise blood pressure and lower potassium—pseudoaldosteronism. Use caution in hypertension, kidney disease, heart failure and hypokalemia. Small harmonizing doses appear in pregnancy formulas; high-dose single-herb courses need a practitioner. Disclose diuretics, digoxin and corticosteroids.
Can Gan Cao tonify Qi, stop cough, stop pain and resolve toxin?
It can help. Spleen deficiency joins ginseng and Atractylodes in Si Jun Zi Tang. Cough joins Ephedra and apricot kernel or loquat leaf. Urgent spasm joins white peony in Shao Yao Gan Cao Tang. Sore throat and sores use the raw root; palpitations with an intermittent pulse use Zhi Gan Cao Tang. It harmonizes and relaxes; it is not a universal antitussive or antidote. Severe arrhythmia and poisoning are emergencies.
Can Gan Cao be steeped daily as a sweet throat tea?
Not as a long-term drink. Sweetness assists damp and stagnates Qi; focal fullness and phlegm-damp grow worse. Accumulated glycyrrhizic acid can raise blood pressure and drop potassium—swollen legs, headache and fatigue. Short raw-licorice use for the throat is reasonable; lasting hoarseness needs an ENT look. Western licorice sweets also contain the acid; do not stack them on a decoction.
How do you choose among Gan Cao, Huang Qi, Dang Shen, honey and Bai Shao?
Astragalus is sweet-warm and ascending: secures the exterior and promotes urination. Codonopsis is sweet-neutral: tonifies the middle and generates fluid. Licorice is sweet-neutral, a weaker tonic, best to harmonize, relax spasm and resolve toxin. Honey moistens the Lung and the stool. White peony is sour-cold: constrains Yin and softens the Liver; with licorice it stops urgent pain. Qi deficiency that should rise favors Astragalus; middle deficiency favors Codonopsis; harmonizing, sore throat and spasm favor licorice. They may be paired; damp fullness and hypertension cap the licorice dose.
Which herbs is Gan Cao combined with? What are the representative formulas?
With ginseng, Atractylodes and Poria it forms Si Jun Zi Tang. With white peony it is Shao Yao Gan Cao Tang. Fearful throbbing and an intermittent pulse join ginseng, raw rehmannia, ass-hide glue and cinnamon twig in Zhi Gan Cao Tang. Sore throat may use Gan Cao Tang; many exterior formulas keep it as envoy. Name raw or honey-fried, and keep it away from Sargassum, kansui, euphorbia and genkwa.
How do you choose and store Gan Cao?
Choose tight fine bark, reddish-brown exterior, ample powder, a yellow-white section with clear radiating rays, and a distinctive sweet taste. Honey-fried slices are deep yellow, smell of toast and are slightly sticky without smearing the hand. Store ventilated and dry, protected from insects. Discard moldy, hollow or bitter unsweet roots. The label should read Gan Cao or Zhi Gan Cao. Buy official slices; do not replace a decoction with licorice candy.

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Medical Disclaimer — This article is provided for educational purposes only and describes traditional Chinese medicine concepts. It is not medical advice, and it is not intended to diagnose, treat, cure or prevent any disease. Always consult a qualified practitioner before using any herb, particularly if you are pregnant, nursing, taking medication or managing a diagnosed condition.

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Gan Cao (Licorice Root): Tonify Spleen Qi, Resolve Toxicity, and Harmonize Formulas