Licorice Root (Gan Cao): The Harmonizer in TCM
Licorice root (gan cao) is one of the most frequently used herbs in TCM, prized for its ability to harmonize formulas and support digestion. Learn about its benefits and uses.
Traditional Chinese Medicine Perspective
Licorice root is sweet, neutral, and slightly warm in nature. It enters all 12 meridians but primarily the Heart, Lung, Spleen, and Stomach. In TCM it is called the "national grandfather" of herbs because it harmonizes and detoxifies other herbs, moderates their harsh properties, and guides them to the right areas. It appears in over 80% of classical formulas.
Health Benefits
- Soothes digestive inflammation and supports gastric health — glycyrrhizin has mucosal-protective effects
- Supports respiratory health by soothing coughs and clearing phlegm
- Anti-inflammatory and adrenal-supporting — traditionally used for fatigue and stress
- Gentle laxative effect that supports regular bowel movements
- Contains antioxidant flavonoids (liquiritin, isoliquiritin) with hepatoprotective properties
How to Use
- 1.Add 1-2 thin slices to soups and broths — a little goes a long way due to its potent sweetness
- 2.Combine with ginger, red dates, and astragalus for a balanced Qi-tonifying tea
- 3.Brew as a standalone tea (1-2 thin slices in hot water for 5 minutes)
- 4.Use the honey-fried version (zhi gan cao) for stronger cough-soothing and Qi-tonifying effects
- 5.Not to be confused with Western licorice candy, which contains much less actual licorice and more sugar
Recipes Featuring This Ingredient
Safety & Precautions
Use in moderation. The glycyrrhizin in licorice can raise blood pressure and lower potassium with prolonged high doses (>15g daily for weeks). Caution with hypertension, heart disease, kidney disease, diuretics, and steroids. Not recommended for pregnant women in large amounts. Avoid if you have hypokalemia (low potassium). Use the "gan cao" variety specifically.
Frequently Asked Questions
Is TCM licorice the same as licorice candy?
No. TCM licorice (gan cao) is the dried root of Glycyrrhiza uralensis, used as a medicinal herb. Licorice candy is mostly sugar and anise flavoring with little actual licorice root.
Why is licorice called the harmonizer?
Gan cao appears in approximately 80% of classical TCM formulas because it harmonizes the actions of other herbs — moderating harsh herbs, enhancing tonic herbs, and guiding the formula to the right areas.
Can I drink licorice tea daily?
1-2 thin slices in 1-2 cups of tea daily is safe for most people. Avoid prolonged high-dose use. Take a break every few weeks to prevent potassium depletion.
What It Actually Is
Licorice root is the root and stolon of Glycyrrhiza uralensis, and of two other species, G. glabra and G. inflata, which are the European and Iranian sources. It is a perennial with a thick, branching underground system, and the commercial material is the dried root and the horizontal stolons, which are yellow-brown outside and bright yellow inside, fibrous, and distinctly sweet. The sweetness is the plant’s defining characteristic and it is genuinely remarkable — glycyrrhizin, the compound responsible, is roughly 30 to 50 times sweeter than sugar, which is why licorice root is used as a sweetener in some contexts and is the base of the anise-flavoured sweets most people know as licorice. It is a genuine herb rather than a food, though it is a genuine one in many traditions, and it is one of the most-used substances in the entire Chinese materia medica.
Where the Description Comes From
Licorice appears in the Shen Nong Bencao Jing, and it has the unusual distinction in this tradition of being simultaneously a sovereign, a minister, an assistant and an envoy — it appears in every tier of the classical formula hierarchy. The reason is the harmonising function: licorice is added to formulas to moderate the harshness of other herbs, to bind the formula together, and to protect the digestion. The Bencao Gang Mu records the same role, and it is worth noting that the same herb appears in both Eastern and Western herbal traditions with a broadly similar use as a demulcent and a sore-throat remedy, arrived at independently. The other thing worth knowing is that licorice candy in the west is a different experience from the root: the confectionery is almost always artificially flavoured with anise rather than made from actual licorice root, which is why people who have never tasted the herb are surprised by it.
What It Does in a Formula
Licorice in this framework does four things, and the first two are what it is famous for. It is a harmoniser — it moderates other herbs and reduces their harshness, which is why it appears in so many formulas. It is a spleen and stomach tonic, and it is used specifically for loose stools and for a weak, dry digestion. It is a lung tonic, and the classical indication is a dry, tickly, unproductive cough — it moistens the lungs and generates fluids, which is why licorice lozenges exist in every culture that has it. And it is a detoxifier in the specific classical sense of guiding and harmonising, not in the modern one of clearing toxins. Those are genuinely different uses and they are worth keeping separate, because the modern misuse of the word is where the safety problems come from.
What to Cook It With
An herb on its own does a fraction of what it does in company. These are the pairings the traditional material actually uses, and what each one is doing there.
The classical pairing in the literal sense — the two are a standard two-herb combination in the materia medica, and they are both in a sweet soup on this site. The dates nourish and protect the stomach; the licorice harmonises and adds a deeper sweetness. Together they do what neither does well alone.
The opposite pairing that is also standard: ginger warms and moves, licorice is neutral to slightly cool and moistening. Together they are the answer to a dry cough with a weak, slightly cold digestion, which is a very common combination in practice.
The most common qi-tonic pairing, and the two are complementary — astragalus builds and pushes, licorice harmonises and protects. Many of the classical qi formulas contain both, and the licorice is what makes them tolerable on a long course.
A warm, moving bark paired with a neutral harmoniser, and the combination is standard for a dry cough with cold extremities. The licorice moderates the cinnamon’s heat, which is a textbook example of the harmonising function doing the job it is named for.
Using It in a Kitchen
Preparation
The root is hard and fibrous. For a decoction, slice it thinly and simmer for 30 to 40 minutes; the sweetness comes out readily and the material gives up its glycyrrhizin steadily, so a long steep is not necessary. In a soup, a small piece or two in a two-hour simmer is enough and the effect is milder than a decoction. It is worth knowing that glycyrrhizin is somewhat water-soluble but not entirely, and that a hot, long decoction extracts more of it than a brief infusion, which matters because the compound is also the one responsible for the adverse effects. Cutting the root exposes more surface and raises extraction; there is no benefit to leaving it whole unless you want a milder, sweeter soup. Store it sealed and dry, and be aware that it will keep for a year.
How much
The classical dose is 2 to 10 grams a day, and 2 to 5 grams is what most of this site’s recipes use — a couple of small slices. Above 10 grams a day, taken daily for weeks, the adverse effects become a real concern rather than a theoretical one, and the official tolerable daily intake recommendations in several countries are in roughly the same range. As a sweetening agent it can be used in tiny amounts, and a quarter-gram will sweeten a pot of tea. There is no reason to exceed the classical range for any of the uses on this page.
Who It Is For, and Who Should Not Use It
Who the traditional use makes sense for
A dry, tickly cough that produces little; a sore throat; a weak digestion with loose stools; a dry mouth and throat; and the specific low-grade fatigue that comes with a spleen qi picture. As a cooking ingredient, it is the thing that makes a herbal soup taste like a herbal soup rather than a punishment, and a great many people use it for that reason alone. It is also one of the safest tonics in general use, and one of the few ingredients on this site that is genuinely used in multiple traditions with a consistent function.
Who should not use it
This is the clearest safety profile on the site and it is a real one, not a hedge. Glycyrrhizin inhibits 11-beta-hydroxysteroid dehydrogenase type 2, which allows cortisol to act on mineralocorticoid receptors. The result is sodium and water retention, potassium loss, and raised blood pressure — and this happens at doses well within the classical range, over weeks, in a substantial proportion of people. There are documented cases of severe hypokalaemia causing arrhythmia from long-term licorice use, and some cases of pseudoaldosteronism. The practical list: do not take it daily for more than a few weeks without a break; avoid it entirely if you have high blood pressure, kidney disease, heart disease or a history of hypokalaemia; it interacts with diuretics, which is the classic dangerous combination since the diuretic lowers potassium and the licorice lowers it further; and it is not a good idea with digoxin for a related reason. If you are pregnant, the amounts in a soup are not a concern and daily use should be discussed.
If You Cannot Get It, or Cannot Take It
The genuine substitute for the harmonising and digestive function, and safer in every respect because it has none of the mineralocorticoid activity. If you want the sweet, mild, stomach-protecting effect that makes licorice a useful cooking ingredient, this is the better choice — and it is the pairing licorice is most often used in anyway.
- Marshmallow root or slippery elm
Outside the tradition, but the closest Western equivalent for the demulcent and throat-soothing function, which is the property that made licorice a throat remedy in every culture that has it. If the reason for the interest is a dry throat, this does the same job with a different mechanism and a much better safety record.
- Anise or fennel
For the flavour rather than the medicine. Actual licorice candy is anise-flavoured and contains no licorice root, which is why someone who has only had the candy has no idea what the herb tastes like. If you want the sweet anise note in a stew, anise seed is the way to get it without any of the pharmacological concern.
What the Research Does and Does Not Show
Licorice is one of the most thoroughly characterised herbs in existence, which produces a slightly unusual result: the pharmacology is well understood and the clinical evidence for its traditional uses is still thin. What is well established is the mechanism of its principal adverse effect, in the detail given above — the 11-beta-HSD2 inhibition, the resulting mineralocorticoid excess, the hypokalaemia and the hypertension — and that has produced official tolerable intake figures and regulatory warnings in several countries. Glycyrrhizin also has documented anti-inflammatory and antiviral activity in laboratory models, and there is some clinical work on topical licorice preparations for skin conditions, and on glycyrrhizin for some liver and gastric indications in Japan where it is a licensed pharmaceutical. For the traditional uses — the cough, the loose stools, the harmonising role — the human evidence is mostly small trials of poor quality, and much of the wider research is on glycyrrhizin as a compound rather than on the root as a food. The overall position is worth stating clearly: a well-understood mechanism for real harm, a plausible pharmacology for the traditional claims, weak clinical evidence for the traditional uses, and an excellent case for treating it as something to use occasionally rather than daily — which is roughly what the classical tradition advised anyway.
A Piece of Common Advice That Is Wrong
“Licorice root is a natural hormone and it balances your adrenal glands, so you can take it daily.” The word “adrenal” and the word “balance” are doing a lot of unsupported work here. Licorice does interact with adrenal and mineralocorticoid biology, and that is precisely why it causes hypertension and potassium loss — it is not a gentle balancing act, it is a pharmacological blockade of a specific enzyme, and the consequence is a genuine medical problem. There is no good evidence that it “supports the adrenals” in the sense meant, and the classic picture of a person who started a tonic for fatigue and developed high blood pressure and leg cramps a few months later is one of the more recognisable presentations of licorice toxicity. It is a fine herb used in small amounts and in short courses. It is not a daily supplement, and “natural” does not modify any of this.
Questions This Ingredient Raises
How long can I take licorice safely?
Short courses and small amounts. The adverse effects are cumulative and dose-related, and the risk rises noticeably beyond a few weeks of daily use. If you want to use it regularly as a cooking ingredient, break it up — a licorice soup two or three times a week rather than daily — and if you are taking it for a cough or a specific aim, two weeks is a sensible frame and then reassess.
What are the warning signs?
The ones to act on: swelling in the ankles or legs, unexplained weight gain, muscle weakness or cramps, an irregular heartbeat, and headaches. All of these are consistent with the potassium loss and sodium retention the compound causes. If you are taking it and notice these, stop it and get a potassium level checked. This is not a theoretical list — there are documented cases of licorice-induced arrhythmia.
Why does my throat lozenge not have the same effect?
Because most throat lozenges contain a small amount of actual licorice, which is what gives the effect, and because the effect is local and brief. The sensation of coating and soothing comes from the same demulcent and anti-inflammatory action, and a lozenge delivers a very small dose directly to the throat. If your lozenge is flavoured with anise and contains no licorice extract, you are getting the flavour and none of the herb.
Is it safe with diuretics?
No, and this is the combination most worth knowing about. Diuretics lower potassium, and licorice lowers potassium by a different mechanism, and the two together have caused serious hypokalaemia and cardiac arrhythmias. If you are on a diuretic for blood pressure, a diuretic for fluid retention, or any medication at all, this is one to raise with your prescriber rather than work out yourself. The same applies to digoxin, because low potassium makes digoxin more toxic to the heart.
Sources and Further Reading
Every claim on this page falls into one of two groups, and they are sourced differently. Statements about the traditional use of an ingredient are references to the classical and modern literature that describes it, and they are not claims that it works. Statements about research point at the published work, including the work that came back negative. Where a search link appears it goes to the current results for that query rather than to a single paper, so you can see the whole record for the ingredient instead of the most favourable part of it.
Reference pages
- Traditional medicine: what it is and what the evidence says — World Health Organization
- Traditional Chinese Medicine: what you need to know — US National Center for Complementary and Integrative Health
- Chinese Text Project — the classical sources, in the original — Chinese Text Project
- Healthy diet: what the World Health Organization actually recommends — World Health Organization
- Dietary supplements: what the FDA regulates and what it does not — US Food and Drug Administration
- All dietary supplement fact sheets, indexed — US National Institutes of Health, Office of Dietary Supplements
- FoodData Central — composition data for every food in this site’s recipes — US Department of Agriculture
- Nutrition: the European food safety authority’s position on claims — European Food Safety Authority
- EFSA publications and opinions — European Food Safety Authority
- PubMed Central — free full text for the papers behind the summaries — US National Library of Medicine
- MedlinePlus — plain-language health information — US National Library of Medicine
- Health information for older adults — US National Institute on Aging
- Aging and nutrition research briefs — US Department of Agriculture, Economic Research Service
- Food safety topics — European Food Safety Authority
- Licorice Root — US National Center for Complementary and Integrative Health
- Licorice — Memorial Sloan Kettering Cancer Center, About Herbs
- Compound profile: Glycyrrhizin — PubChem, US National Library of Medicine
Search the evidence yourself
- How good is the evidence in traditional Chinese medicine? — systematic reviews of trial quality — PubMed
- Adverse events in traditional Chinese medicine — systematic reviews of what is reported and what is not — PubMed
- Licorice and glycyrrhizin — blood pressure and safety — PubMed
- Licorice — clinical trials including ulcerative colitis — PubMed
- Licorice — hypokalaemia and mineralocorticoid effects — PubMed
- Registered trials using licorice — ClinicalTrials.gov
Disclaimer
This website is a personal learning project and does not provide medical advice. All content is for informational and educational purposes only, based on traditional food therapy concepts and publicly available nutritional information.
- I am not a licensed physician, dietitian, or TCM practitioner. Nothing on this site should be interpreted as medical diagnosis, treatment, or prescription.
- Traditional food therapy concepts (Qi, Yin/Yang, Dampness, etc.) are cultural/philosophical frameworks, not clinically proven medical models.
- Individual responses to foods and herbs vary widely. What works for one person may not work for another, or may cause adverse effects.
- Always consult a qualified healthcare professional before making dietary changes, especially if you have a medical condition, take medications, are pregnant, or are nursing.
- If you experience persistent symptoms, seek medical attention promptly. Do not delay or disregard professional medical advice because of something you read here.
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