Gan Cao – Licorice – Glycyrrhiza

Gan caoGan Cao – Licorice – Glycyrrhiza


Licorice / Gan Cao  in Traditional Chinese Medicine

Licorice is a common herbal tonic in Traditional Chinese Medicine. Appearing in hundreds of herbal formulas, this familiar root with the unforgettable taste comes in two forms:

Gan Cao (甘草), raw, unprocessed licorice root, and

Zhi Gan Cao (炙甘草), “honey-fried,” processed licorice root.

The distinction makes a difference in how the herbs work to support health.

Raw licorice, Gan Cao, has a “raw” effect on the movement of the mysterious energy called Chi. Raw licorice adds energy to the Spleen, which is a metaphor for the general digestive function.  When the digestive tract does not have the energy to complete the digestion of food, and is releasing undigested food through loose bowels, raw licorice gives it extra energy so that diarrhea stops. When the abdomen does not have the energy to hold its muscles in their normal relationship, raw licorice energizes them to stop spasms and pain. Raw licorice also detoxifies substances that take the body’s normal Chi. And it “guides” the energies of other herbs in a formula into their proper Chi channels.

Processed licorice, Zhi Gan Cao, is usually a “made to order” item in a Chinese herbal apothecary. It doesn’t sit around for months waiting to be sold. It’s cooked, usually in honey, for immediate use.

honey fried Gan cao

The process of “frying” the herb in honey enables Zhi Gan Cao to “harmonize” other energies, not just those of the digestive tract, but also those of the heart. Zhi Gan Cao might be added to a formula when one of the symptoms is a weak pulse, or low blood pressure. But it may also be added to a formula when one of the symptoms is melancholy, not having the “heart” to face a life situation.

It turns out that the traditional understanding of licorice in energy terms mirrors the modern scientific understanding of licorice in pharmaceutical terms.

Taking Too Much Licorice for Too Long Can Result in Hypertension and Hypokalemia

It’s well known from medical observation that taking using too much raw licorice (Gan Cao) per day or processed licorice (Zhi Gan Cao) in herbal teas can have two untoward effects. First of all, there can be high blood pressure, sometimes dangerously high blood pressure. This is the natural result of “energizing” the heart. Secondly, the body responds to licorice by lowering potassium levels. The resulting hypokalemia (low serum potassium) can result in a variety of heart-related problems, including ventricular tachycardia and in some cases ventricular fibrillation followed by cardiac arrest. Perturbations of potassium levels can cause weakness, swelling, and occasionally encephalopathy, swelling of the brain.

How much Gan Cao / licorice is too much?

  • If you don’t have an underlying health problem, it is generally dangerous to take more than 20 g of licorice per day in teas for more than six weeks. If you don’t have high blood pressure, you may develop it.[1]
  • The life-threatening manifestations of licorice poisoning occur only after consumption of vastly more licorice than any practitioner of Traditional Chinese Medicine would ever prescribe. There is a case report of a woman who recovered from brainstem swelling and muscle breakdown after taking licorice—but she was using a pound (about 450 grams) a day, not the 5 to 15 grams a day that would appear in a professionally prescribed herbal formula.[2] It’s important to remember that licorice is a “medicine,” not a food.
  • To be on the safe side, most authorities recommend that people who already have high blood pressure should not take more than 5 g of licorice per day in teas or herbal formulas. If you have high blood pressure, a professionally trained herbalist will notice, and will not prescribe you too much. But you do need to be able to remember how much licorice you have already had in any given day before you take more. If you have memory problems, leave licorice alone.[3]

What’s Gan Cao / Licorice Good For?

Don’t let the fact that licorice has to be taken in moderate amounts discourage you from using it with professional guidance to support good health. Here are some of the evidence-based applications of the herb:gan cao

  • Licorice extracts can relieve hot flashes associated with menopause. A clinical trial in Iran found that taking 1140 mg of licorice extract a day was more effective at reducing the duration of hot flashes than estrogen replacement therapy, but that estrogen replacement therapy was more effective than licorice for reducing the frequency and severity of hot flashes. Both products work, but they work in different ways.[4] Extract taken 1140 mg a day is usually a safe dose of licorice for women who don’t already have high blood pressure.
  • Licorice creams fight eczema. Both traditional herbal teas and skin creams that contain licorice will relieve itching and redness caused by eczema or atopic dermatitis, but there’s no dangerous of overdose if you use the cream. Clinical studies prove that the creams work. In one clinical trial, applying gel formulations containing 1% or 2% licorice root extract three times daily for 2 weeks seems to reduce erythema by 35% to 61%, edema by 57% to 84%, and itching by 44% to 73%. The stronger, 2% licorice cream works better than the 1% cream.[5]
  • Licorice teas relieve indigestion. Clinical testing in Germany has shown that various herbal teas that contain licorice and peppermint as their main ingredients relieve acid reflux, belching, flatulence, vomiting, and diarrhea. What’s important to remember is that these teas don’t contain just licorice. They also contain other herbs such as the previously mentioned peppermint, and caraway, lemon balm, or the oddly named clown’s mustard. [6]Use a commercial product that has already measured out these herbs for you. Take it after meals.
  • Using deglycyrrhizinated licorice (DGL) as a mouthwash relieves the pain of canker sores fast. The kind of licorice you use for canker sores is neither Gan Cao or Zhi Gan Cao. It’s an extract of licorice that has removed the glycyrrhizin that can interfere with potassium balance. It’s safe to swallow the mouthwash as long as it is made with DGL, not any other form of licorice. A clinical trial in India found that DGL mouthwashes relieved canker sore pain in 75% of patients in just one day, and completely healed canker sores in 75% of patients in three days.[7]
  • Licorice creams can also lighten age spots, although you won’t find an effective product that contains just Applying a topical cream (Clariderm Clear, Stiefel Laboratories Inc., Guarulhos, SP, Brazil) containing licorice, emblica, and belides twice daily for 60 days is as effective as a cream containing 2% hydroquinone for lightening the skin in patients with age spots (melasma). The advantage of this herbal product over the more commonly used hydroquinone is that the herbs remove brown pigments without the side effect (usually on people with golden skin tones) of adding blue pigment.[8]

Licorice / Gan Cao in Herbal Products Best Used Under a Doctor’s Supervision

There are also specialized uses of licorice with other herbs that get remarkable results, but you can only get these products from your doctor.

  • Stabilizing hepatitis C. Stronger Minophagen C is a prescription formulation of glycyrrhizin extracted from licorice that stops liver damage caused by hepatitis C long enough to stabilize patients so they can receive other treatments. It has to be given by IV, but it reduces mortality from hepatitis C by about 50%.[9] Used long-term, it also reduces the risk of liver cancer in people who have active hepatitis C.[10]
  • Lowering cholesterol. A preliminary clinical trial found that taking 100 mg of licorice extract every day for a month one month reduced plasma total cholesterol levels by 5%, plasma low-density lipoprotein (LDL) cholesterol levels by 9%, and plasma triglyceride levels by 14% compared with baseline in patients with moderately high cholesterol.[11] You could try this on your own, but don’t use any licorice product for high cholesterol for more than one month at a time, and keep your consumption of extract limited to 100 mg a day.

There are even more exciting applications of licorice in combination with other herbs that you would get through a medically trained doctor of both western and Traditional Chinese Medicine. The licorice based formula sho-saiko-to has clinically proven efficacy against hepatitis B, although it absolutely, positively must not be given to people who have had interferon treatment.  Licorice and Peony Decoction can affect not just how women lactate, but also how they relate to their babies. Dozens of formulas that contain licorice can be useful in treating inflammatory bowel disease, peptic and duodenal ulcers, and irritable bowel syndrome.

But don’t attempt to use complex formulas entirely on your own. See a specialist trained in herbal medicine. Take advantage of the best professional health to get the best results of licorice in its many forms for supporting your good health.

[1] Sigurjonsdottir HA, Ragnarsson J, Franzson L, Sigurdsson G. Is blood pressure commonly raised by moderate consumption of liquorice? J Hum Hypertens 1995;9:345-8.

[2] Chatterjee, N., Domoto-Reilly, K., Fecci, P. E., Schwamm, L. H., and Singhal, A. B. Licorice-associated reversible cerebral vasoconstriction with PRES. Neurology 2010;75(21):1939-1941.

[3] Janse A, van Iersel M, Hoefnagels WH, Olde Rikker MG. The old lady who liked liquorice: hypertension due to chronic intoxication in a memory-impaired patient. Neth J Med 2005;63:149-50.

[4] Menati L, Khaleghinezhad K, Tadayon M, Siahpoosh A. Evaluation of contextual and demographic factors on licorice effects on reducing hot flashes in postmenopause women.Health Care Women Int. 2014 Jan;35(1):87-99. doi: 10.1080/07399332.2013.770001. Epub 2013 May 10. PMID: 23663094.

[5] Saeedi, M., Morteza-Semnani, K., and Ghoreishi, M. R. The treatment of atopic dermatitis with licorice gel. J Dermatolog Treat 2003;14(3):153-157.

[6] Madisch A, Holtmann G, Mayr G, et al. Treatment of functional dyspepsia with a herbal preparation. A double-blind, randomized, placebo-controlled, multicenter trial. Digestion 2004;69:45-52.

[7] Das SK, Das V, Gulati AK, and et al. Deglycyrrhizinated liquorice in aphthous ulcers. J Assoc Physicians India 1989;37(10):647.

[8] Costa, A., Moises, T. A., Cordero, T., Alves, C. R., and Marmirori, J. Association of emblica, licorice and belides as an alternative to hydroquinone in the clinical treatment of melasma. An Bras Dermatol 2010;85(5):613-620.

[9] Acharya SK, Dasarathy S, Tandon A, et al. A preliminary open trial on interferon stimulator (SNMC) derived from Glycyrrhiza glabra in the treatment of subacute hepatic failure. Indian J Med Res 1993;98:69-74.

[10] Arase, Y., Ikeda, K., Murashima, N., Chayama, K., Tsubota, A., Koida, I., Suzuki, Y., Saitoh, S., Kobayashi, M., and Kumada, H. The long term efficacy of glycyrrhizin in chronic hepatitis C patients. Cancer 1997;79(8):1494-1500.

[11] Fuhrman, B., Volkova, N., Kaplan, M., Presser, D., Attias, J., Hayek, T., and Aviram, M. Antiatherosclerotic effects of licorice extract supplementation on hypercholesterolemic patients: increased resistance of LDL to atherogenic modifications, reduced plasma lipid levels, and decreased systolic blood pressure. Nutrition 2002;18(3):268-273.



The information and reference materials contained here are intended solely for the general information of the reader. It is not to be used for treatment purposes, but rather for discussion with the patient’s own physician. The information presented here is not intended to diagnose health problems or to take the place of professional medical care.

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