Herb

Gan Cao

Licorice | 甘草

Also known as:

Licorice , Raw licorice root

Gan Cao

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Properties

Qi-tonifying herbs (补气药) · Neutral

Traditionally supports*

Digestive Health Respiratory Health Throat Health Muscle cramp relief

Parts Used

Root (根 gēn)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

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About This Herb

Traditional Chinese Medicine background and properties

Herb Description

One of the most widely used herbs in all of Chinese medicine, licorice root supports digestion, soothes sore throats, relieves muscle cramps, and helps other herbs in a formula work together harmoniously. The ancient Chinese called it 'The Elder Statesman' (Guó Lǎo) because of its ability to mediate and balance the actions of other medicinal ingredients. It appears in more classical formulas than almost any other herb.

Herb Category

Qi-tonifying herbs (补气药)

Main Actions

  • Tonifies the Middle and Augments Qi
  • Clears Heat and Resolves Toxicity
  • Expels Phlegm and Stops Cough
  • Relaxes Spasms and Relieves Urgency
  • Harmonizes Other Herbs

How These Actions Work

'Tonifies the Spleen and augments Qi' means Gān Cǎo strengthens the digestive system and boosts the body's vital Qi. Because it is sweet in taste and enters the Spleen and Stomach channels, it naturally supplements the middle Qi that the Spleen produces. This makes it useful for tiredness, poor appetite, loose stools, and shortness of breath that come from a weakened digestive system. In the honey-prepared form (Zhì Gān Cǎo), this tonifying action is significantly enhanced.

'Clears Heat and resolves toxins' applies specifically to the raw, unprocessed form (Shēng Gān Cǎo). Despite being neutral in temperature overall, raw licorice has a slightly cooling quality that allows it to clear Heat-toxins. This is why it is used for sore throat, skin abscesses, boils, and mouth ulcers, often paired with herbs like Jīn Yín Huā (honeysuckle) or Jú Gěng (platycodon). It also helps neutralize the toxicity of other herbs and even some ingested poisons.

'Expels Phlegm and stops cough' reflects licorice's ability to moisten the Lungs and help clear Phlegm from the airways. It enters the Lung channel and is sweet and moistening, making it suitable for coughs of almost any type, whether from cold, heat, dryness, or deficiency.

'Relaxes spasm and stops pain' (缓急止痛 huǎn jí zhǐ tòng) means the herb can relieve cramping and spasmodic pain, particularly in the abdomen and limbs. The classical example is Sháo Yào Gān Cǎo Tāng (Peony and Licorice Decoction), where licorice works with white peony to ease muscle cramps and leg spasms.

'Moderates and harmonizes other herbs' is perhaps licorice's most famous role. Its sweet, gentle nature buffers the harsh or toxic properties of other herbs in a formula, softens strong flavours, and helps different ingredients work together smoothly. This is why classical Chinese physicians nicknamed it Guó Lǎo ('The Elder Statesman') and why the saying goes 'nine out of ten prescriptions contain Gān Cǎo.'

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony that reveal what's out of balance in the body. Gan Cao is traditionally associated with these specific patterns.

The following describes this herb's classification within Traditional Chinese Medicine theory and is provided for educational purposes only.

Why Gan Cao addresses this pattern

Gān Cǎo is sweet in taste and enters the Spleen and Stomach channels, making it a natural supplement for weakened digestive Qi. When the Spleen fails to properly transform food into Qi and Blood, symptoms like fatigue, poor appetite, and loose stools appear. Gān Cǎo's sweet, tonifying nature directly replenishes the Spleen's Qi, and its gentle quality makes it safe even for patients who are quite depleted. In this pattern, the honey-processed form (Zhì Gān Cǎo) is preferred for its stronger warming and tonifying effect.

A practitioner would look for one or more of these signs

Eye Fatigue

Tiredness and lack of stamina from weakened digestive function

Poor Appetite

Reduced desire to eat

Loose Stools

Soft or unformed bowel movements

Shortness Of Breath

Mild breathlessness on exertion

TCM Properties

Temperature

Neutral

Taste

Sweet (甘 gān)

Channels Entered
Heart Lungs Spleen Stomach
Parts Used

Root (根 gēn)

This is partial information on the herb's TCM properties. More detailed information is available on the herb's dedicated page

Product Details

Manufacturing, supplier, and product specifications

Product Type

Granules

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Botanical & Sourcing

Quality Indicators

Good quality Gan Cao root is cylindrical, long, and relatively thick (0.6-3.5 cm diameter). The outer skin should be tight-fitting (not loose or peeling), reddish-brown in colour, and finely textured. The cross-section should be yellowish-white with a clear visible cambium ring and distinct radial lines, showing a floury (powdery) texture. The herb should feel solid and heavy when held. The taste should be distinctly sweet with a characteristic subtle flavour. The traditional saying is: 'skin fine and red, solid in texture, cross-section yellowish-white, powdery, and sweet in taste' (皮细色红、质坚实、断面色黄白、粉性足). The best grade, historically called 'Fen Cao' (粉草, powdery licorice), has a large diameter and tight cross-section with clear markings. Avoid roots that are thin, light, pithy, fibrous without powder, dark-coloured internally, or bitter-tasting.

Primary Growing Regions

The premier terroir (道地药材) region for Gan Cao is Inner Mongolia (especially the Alashan League and Ordos area), often called 'Liang Wai Cao' (梁外草). Other major production areas include Gansu, Ningxia, and Xinjiang. Inner Mongolia, Gansu, and Ningxia produce the highest quality, while Xinjiang has the largest total output. Historically, the herb from Inner Mongolia's western arid desert-margin grasslands has been most prized. Within the trade, herb from western regions is called 'Xi Cao' (西草) and from eastern regions 'Dong Cao' (东草). Glycyrrhiza inflata and Glycyrrhiza glabra are mainly produced in Xinjiang and Gansu.

Harvesting Season

Spring and autumn, with autumn harvest preferred. Roots are best at 3-4 years of growth.

Supplier Information

Treasure of the East

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Usage & Safety

How to use this herb and important safety information

Important Medical Disclaimer

The information provided here is for educational purposes only and is not intended as medical advice or to replace consultation with a qualified healthcare professional. This herb is a dietary supplement and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease.

Always consult with a qualified healthcare provider, particularly if you are pregnant, nursing, have a medical condition, or are taking other medications. Discontinue use and consult your healthcare provider if you experience any adverse reactions.

Recommended Dosage

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Instructions for safe storage and consumption

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Traditional Dosage Reference

Standard

2-10g

Maximum

Up to 30g in acute situations (e.g. severe poisoning, acute sore throat), for short-term use under practitioner supervision. For daily formulas, do not exceed 10g without specific clinical justification.

Notes

Use lower doses (2-6g) when Gan Cao serves as an envoy herb to harmonise a formula or moderate harsh properties of other herbs. Use moderate doses (6-10g) for tonifying Spleen Qi, relieving cough, or alleviating pain. Higher doses (10-30g) may be used short-term for clearing Heat-toxins (raw Gan Cao) or in acute poisoning situations. Raw Gan Cao (Sheng Gan Cao) is preferred for clearing Heat, resolving toxins, and soothing the throat. Honey-roasted Gan Cao (Zhi Gan Cao) is preferred for tonifying Qi, nourishing the Heart, and harmonising the Middle Jiao. When using doses above 10g or for periods longer than 4-6 weeks, monitor blood pressure and serum potassium. Elderly patients and those with pre-existing cardiovascular or renal conditions require more conservative dosing.

Processing Methods

Processing method

Stir-fried with honey (蜜炙). The sliced root is mixed with a measured amount of refined honey diluted with a small amount of water, allowed to absorb, then stir-fried over a gentle flame until it turns golden-yellow to deep yellow and is no longer sticky to the touch.

How it changes properties

Honey-processing shifts the herb's temperature from neutral toward slightly warm. It greatly enhances the Qi-tonifying and Spleen-strengthening action, and adds the ability to tonify Heart Qi and restore the pulse (益气复脉). The Heat-clearing and toxin-resolving actions of raw licorice are significantly reduced or lost. The honey further increases the moistening quality.

When to use this form

Use Zhì Gān Cǎo when the goal is to tonify Qi, especially Spleen and Heart Qi. Key indications include fatigue, poor appetite, loose stools from Spleen Qi Deficiency, and irregular heartbeat (palpitations with a knotted or intermittent pulse). This is the form used as the King herb in Zhì Gān Cǎo Tāng (Honey-Prepared Licorice Decoction) for heart palpitations and arrhythmia.

Toxicity Classification

Non-toxic

Gan Cao is classified as non-toxic in the Chinese Pharmacopoeia and is one of the safest herbs in the materia medica. However, its main active compound glycyrrhizin can cause pseudoaldosteronism when consumed in high doses or over prolonged periods. The mechanism involves glycyrrhetinic acid (a metabolite of glycyrrhizin) inhibiting 11β-hydroxysteroid dehydrogenase type 2 in the kidneys, which allows cortisol to activate mineralocorticoid receptors. This results in sodium and water retention, potassium loss, elevated blood pressure, and edema. The amount of glycyrrhizin estimated to produce these side effects in normal subjects is 0.7-1.4g, corresponding to roughly 10-14g of crude herb taken daily over an extended period. These effects are dose-dependent and reversible upon discontinuation. Risk factors include older age, pre-existing hypertension, constipation, hypoalbuminemia, and concurrent use of potassium-depleting medications.

Contraindications

Caution

Edema or fluid retention conditions. Gan Cao's sweet flavour can promote dampness and fluid retention, and its glycyrrhizin content causes sodium and water retention through pseudoaldosteronism. Use is contraindicated in patients with existing edema.

Caution

Hypertension. The glycyrrhizin metabolite glycyrrhetinic acid inhibits 11-beta-hydroxysteroid dehydrogenase type 2 (11β-HSD2) in the kidneys, leading to mineralocorticoid-like effects that raise blood pressure. Avoid prolonged use or high doses in hypertensive patients.

Avoid

Hypokalemia or patients at risk of low potassium (e.g. those on potassium-depleting diuretics). Gan Cao promotes potassium excretion through its pseudoaldosterone effect, which can cause dangerously low potassium levels, cardiac arrhythmias, and muscle weakness.

Avoid

Congestive heart failure or severe kidney disease. Sodium and water retention caused by glycyrrhizin can worsen cardiac and renal congestion.

Caution

Dampness with abdominal bloating and fullness (湿盛中满). Gan Cao's sweet, moistening nature can worsen dampness accumulation and cause distension. Classical texts warn that it can 'assist dampness and obstruct Qi, causing abdominal fullness.'

Caution

Nausea and vomiting due to excess dampness. The sweet, cloying nature of Gan Cao can aggravate these symptoms.

Avoid

Patients on digoxin or other cardiac glycosides. Gan Cao-induced hypokalemia increases the toxicity of cardiac glycosides and may precipitate dangerous arrhythmias.

Caution

Long-term use at high doses (exceeding 10g daily for more than 4-6 weeks) without medical supervision. Prolonged use increases the risk of pseudoaldosteronism with hypertension, hypokalemia, and edema.

Classical Incompatibilities

Gan Cao is incompatible with Gan Sui (甘遂, Radix Kansui), Da Ji (大戟, Radix Euphorbiae Pekinensis / Radix Knoxiae), Yuan Hua (芫花, Flos Genkwa), and Hai Zao (海藻, Sargassum) according to the Eighteen Incompatibilities (十八反). The classical mnemonic verse states: '藻戟遂芫俱战草' (Seaweed, Euphorbia, Kansui, and Genkwa all war against Cao). This prohibition was first recorded in the Ben Cao Jing Ji Zhu by Tao Hongjing, was later formalised as a verse in the Ru Men Shi Qin, and is codified in the Chinese Pharmacopoeia. Note: some historical formulas (e.g. Gan Sui Ban Xia Tang from the Jin Gui Yao Lue, Hai Zao Yu Hu Tang) deliberately combine Gan Cao with its 'incompatible' partners for specific therapeutic purposes, but this requires expert judgement and is not standard practice.

Special Populations

Pregnancy

Use with caution during pregnancy. While Gan Cao is not classified as a prohibited herb in pregnancy and is included in many classical formulas used during pregnancy at low doses, modern research suggests potential concerns. Glycyrrhizin may affect cortisol metabolism through inhibition of 11β-HSD2, and there are reports suggesting that high licorice intake during pregnancy may be associated with preterm labour and adverse developmental outcomes. Standard low doses (2-6g) as part of a balanced formula for short periods are generally considered acceptable under professional guidance. Avoid high doses or prolonged independent use during pregnancy.

Breastfeeding

No specific prohibition during breastfeeding at standard doses. Glycyrrhizin and its metabolites may transfer into breast milk, and the potential for mineralocorticoid-like effects (fluid retention, blood pressure changes) in the nursing infant has not been well studied. Low doses within balanced formulas are generally regarded as acceptable for short-term use. Prolonged high-dose use should be avoided. Monitor the infant for signs of fluid retention or irritability.

Pediatric Use

Gan Cao is widely used in paediatric formulas at reduced doses appropriate to the child's age and weight. As a general guide, children under 6 may use one-third to one-half the adult dose, while children 6-12 may use one-half to two-thirds. However, because Gan Cao can promote fluid retention and affect electrolyte balance, prolonged use at higher doses should be avoided in children. Monitor for signs of edema or blood pressure changes with extended use.

Drug Interactions

Cardiac glycosides (digoxin): Gan Cao-induced hypokalemia significantly increases the risk of digoxin toxicity and cardiac arrhythmias. Concurrent use should be avoided or carefully monitored with regular potassium level checks.

Thiazide and loop diuretics (hydrochlorothiazide, furosemide): Both Gan Cao and these diuretics promote potassium loss. Combined use increases the risk of severe hypokalemia. Monitoring of electrolytes is essential.

Antihypertensive medications: Gan Cao's sodium- and water-retaining properties can directly counteract the effects of antihypertensive drugs, reducing their efficacy and worsening blood pressure control.

Corticosteroids (prednisone, prednisolone): Glycyrrhizin inhibits the breakdown of corticosteroids, potentiating their effects and increasing the risk of corticosteroid side effects including adrenal suppression, hyperglycaemia, and immunosuppression.

Warfarin and anticoagulants: Hypokalemia from Gan Cao may alter cardiac rhythm and complicate anticoagulant therapy. The interaction is indirect but clinically relevant.

Oral hypoglycaemic agents and insulin: Glycyrrhizin may affect blood glucose levels. Patients using diabetes medications should monitor blood sugar closely when taking Gan Cao.

CYP3A4 substrates: Licorice root extract and glabridin have been shown to inhibit CYP3A4, a major drug-metabolising enzyme, potentially increasing blood levels of many medications metabolised by this pathway.

Dietary Advice

When taking Gan Cao, especially at higher doses or for extended periods, favour potassium-rich foods such as bananas, sweet potatoes, leafy greens, and beans to help offset its potassium-depleting effect. Reduce salt intake, as Gan Cao already promotes sodium retention. Avoid excessive consumption of other sweet or damp-producing foods (rich dairy, greasy fried foods, excessive sugar) that may compound Gan Cao's tendency to generate dampness. Classical sources note that Hai Zao (seaweed/sargassum) should not be consumed with Gan Cao due to their incompatibility.

Cautions & Warnings

Although this herb is typically safe for most individuals, it may cause side effects in some people. Pregnant women, nursing mothers, postpartum women, and those with liver disease should use the formula with caution.

As with any Chinese herbal remedy, it is advisable to seek guidance from a qualified TCM practitioner before beginning treatment.