Below is a breakdown of Licorice, a widely used herb that commonly comes with safety warnings for its potential herb-drug and herb-herb interactions. What part of it is problematic, what are its active constituents, what exactly are the contraindications, who should worry about it, what can we conclude from the safety data, and what do I personally think about this herb? Read about it below.
Herb: Glycyrrhiza galabra ( Licorice )
Constituents: Oleannane triterpenes (glycyrrhizin [mixture of calcium and potassium salts], glycyrrhetic acid, and phytosterols); flavanone; isoflabanoids; chalcones; polysaccharides (mainly glucans); volatile oil (containing fenchone, linalool, furfural alcohol, benzaldehyde); miscellaneous: starch, sugars, amino acid. (Hoffmann, 2003) (MacLennon & Koog, 2014)
Potentially problematic constituents: glycrrhizic acid (NCCIH, 2020)
Contraindications: Prolonged use with thiazide and loop diuretics and cardiac glycosides is contraindicated. Licorice shouldn’t be used with spironolactone or amiloride. (Hoffmann, 2003) Patients taking cardiac glycosides, hypotensive agents, corticoids, diuretic drugs or monoamine oxidase inhibitors should not take this herb either as it is not recommended. (Hoffmann, 2003)
Herb-drug interactions: Corticosteroids and thiazide diuretics can cause potentiation, and digitalis or other cardiac glycosides can cause increased sensitivity. Though these were reported for Glycyrrhiza uralensis (Chinese licorice) and not Glychyrrhiza galabra, they are similar enough that this these warnings should be considered. (Dharmananda, 2020)
Side effects/adverse effects: Hofffmann reports that the side effects of licorice are minimal if daily intake of glycyrrhizin is less than 10mg, but that chronic use may cause hypokalemia, headaches, spastic numbness, hypertension, weak limbs, dizziness and edema. (Hoffmann, 2003) It may also cause decreased potassium and blood pressure, which is of concern for people with high blood pressure, or heart or kidney disease. These side effects are believed to be caused by glycrrhyzic acid. (NCCIH, 2020)
A documented adverse reaction to licorice was reported when a 51-year-old female was diagnosed with serious hypertension after taking an herbal medicine containing licorice. She was clinically diagnosed as having licorice intoxication, as she did not present with hypertension after ceasing the herbal medicine. It was discovered that she was heterozygous for wild-type and mutant HSD11B2 genes after taking licorice for over a year; therefore those with this gene mutation should not take licorice. (Harahap et al, 2011)
At risk populations: Heavy consumption of licorice during pregnancy has been associated with premature birth and health problems of the child. (NCCIH, 2020) A study showed that heavy consumption of 500mg a week versus low consumption of less than 250mg a week resulted in a twofold increase in preterm delivery of less than 37 weeks. (MacLennan & Koog, 2014) People with an HSD11B2 gene mutation should avoid licorice, as it can produce overt hypertension in those without a history of hypertension. (Harahap et al, 2011)
Summary of found data/conclusion: The safety of licorice seems to depend upon how much is used over how long of a period of time, and whether or not it has been dyglycyrrhizized. If the herb has been dyglycrrhizinated, called DGL, then it seems to have a much lesser degree of side effects. I concluded that it is still the dosage of licorice that matters in terms of side effects. I found this to be reported pretty much throughout everything I read, and from personal experience, have only really worked with DGL in terms of supplements from companies using licorice responsibly, as DGL is known to be “safer” for the general public because of hypertension issues an such. Regarding its safety for pregnant women, the study I read was done through a retrospective postnatal questionnaire, so it is quite possible that the actual amount of licorice consumed was different than the amount reported. None the less, licorice use in what the women recalled and qualified as a high amount was related to their preterm babies birth, so as with any other herb, and as with any other health condition, it should not be used in high amounts. The article also mentioned a study done in Korea regarding a correlation with licorice use during pregnancy and stillbirths, though when the authors broke the data down, they did not find the study to be statistically relevant. They concluded that “it is wrong for practitioners to be expected to continue to exercise such caution predicated on the basis of flawed clinical trials and skewed data analysis. The authors believe that, at present, there is insufficient information to categorically state whether or not glycyrrhiza may be used safely in pregnancy.” (Dharmananda, 2020) After everything I researched, I agree with their conclusion.
I do not get the impression that licorice is dangerous, though one should be prudent with whatever herb or supplement is taken. I do agree that high amounts should be taken with caution- though this is true with anything, as we know dosage matters. Licorice has so many immune system, liver, endocrine and lung benefits that it should not be ruled out, but it should not be abused. (Hoffmann, 2003) I did not find any contraindications for children or for the elderly, but wasn't surprised to find warnings for pregnant women.
References:
Hofffmann, D. (2003) Materia Medica, The Science and Practice of Herbal Medicine. Healing Arts Press. Rochester, VT.
MacLennan, E. Koog,YH. (2014) A re-analysis of studies regarding the use of Glycyrrhiza spp. in women during pregnancy. Journal of Herbal Medicine, Volume 4, Issue 2.
ISSN 2210-8033. Retrieved from: https://doi.org/10.1016/j.hermed.2014.01.005.
Dharmananda, S. (2020) The Interactions of Herbs and Drugs. Institute for Traditional Medicine, Portland, Oregon. Retrieved from: http://www.itmonline.org/arts/herbdrug.htm
Harahap, I. Sasaki, N.Gunadi. Yusoff, S. Lee, M. Morikawa, S. Nishimura,N. Sasaki, T. Usuki, S. Hirai, M. Ohta, M. Takaoka, Y. Nishimoto, Nishio, T. (2011) ”Herbal Medicine Containing Licorice May Be Contraindicated for a Patient with an HSD11B2 Mutation", Evidence-Based Complementary and Alternative Medicine, vol. 2011, Article ID 646540. Retrieved from: https://doi.org/10.1093/ecam/nep211
National Center for Complementary and Integrative Health. (2020) Health Information [Licorice Root] Retrieved from: https://www.nccih.nih.gov/health/licorice-root
Image credit: pic hosted by https://pixabay.com/photos/licorice-root-herbal-natural-2543337/ image taken by gate 74 at https://pixabay.com/users/gate74-5942741/