Glycyrrhiza glabra

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Latest Edit: Hector 2014-03-18 (EDT)

See Also Botanical Monographs

Licorice (Glycyrrhiza glabra') is used in many formulations to activate and increase the effects of other herbs. It acts similar to hydocortisone, has anti-inflammatory, demulcent and many other properties making licorice effective in a number of conditions. To explore the characteristics, medicinal uses and prescribing considerations of this herb in more detail, check out the references indicated.[1], [2]



Historical Uses:

Glycyrrhiza was first described by Theophrastus for pectoral diseases. It has also been used as a flavouring to disguise the taste of medicine. Historically it has been used for coughs, thirst in dropsy, peptic ulcers, asthma, pharyngitides, malaria, abdominal pain, insomnia, and infections.

Medicinal Uses:

Article Botanical Approaches to Adrenal Insufficiency, Vital Link; 2006 Fall
  • Other Conditions
  • Stop smoking forumlations
  • used as a natural alternative to hydrocortisone
  • decrease free radicals and inflammation

Prescribing Considerations

Do not take for longer than 6-8 weeks if taking high daily dose.

The information provided is intended to augment the treatment from a naturopathic doctor or other trained medical professional. Although most herbs are generally safe, it is recommended that you avoid self-prescribing especially when there is an underlying ongoing medical condition, if you are on any prescription medications or if you are pregnant or breastfeeding.

Formulations and Preparation

  • Decoction (root) - 1/2-1 tsp three times daily
  • Tincture - 1-3mL (1:5, 40%) three times daily
  • Solid extracts - 1/4 tsp three times daily
  • Dried root - 2-12g daily or 20-25g daily, divided doses after meals
  • Ulcers - 1.2-4.6g daily of deglycyrrhizinated licorice (DGL)
  • Asthma - 1-3 tsp tincture before bed


The safety and prescribing considerations for this herb include:[4] [5]

  • Generally regarded as safe.
  • Side-effects are pseudoaldosteronism (which presents as hypernatremia, hypokalemia, hypertension, headache, edema, lethargy, and can lead to congestive heart failure). Deglycyrrhizinated licorice (DGL) is not associated with adverse side effects.
  • Cautions and Contraindications: pre-existing cardiovascular disease especially hypertension, liver or kidney dysfunction, pregnancy (safety not established), lactation, diabetes, estrogen replacement therapy, recovery from alcoholism overweight individuals
  • Drug-Herb Interactions.[4]
  • Acetaminophen - Beneficial or supportive interaction with professional management, prevention or reduction of drug adverse effect; Licorice induces UGT1A and increases clearance of acetaminophen (minor significance for acetaminophen due to multiple pathways of the drug's metabolism).
  • Acetylsalicylic Acid and Other Gastroirritant and Ulcergenic Agents - Beneficial or supportive interaction with professional management; Licorice helps reduce gastroirritant adverse effects of aspirin (clinically significant, anecdotally applicable to other drugs such as NSAIDs, mucositis-inducing chemotherapy agents, and ethanol).
  • Antibiotics and Antimicrobial Agents (Systemic) - Adverse drug effect on herbal therapeutics with strategic concern; Activation by hydrolysis of licorice glycosides to aglycone depends on bowel flora. Antibiotics reduce bowel flora number and function and may reduce herb bioavailability. Use probiotics or DGL if appropriate.
  • Beta-lactam Antibiotics - Potential or theoretical beneficial or supportive interaction with professional management; Licorice constituents reduce or reverse drug resistance to MRSA when combined with beta-lactam antibiotics.
  • Cimetidine and Related Histamine (H2) Receptor Antagonists - Potential or theoretical beneficial or supportive interaction with professional management; Synergistic increase in ulcerprotective and ulcer-healing properties suggested by combination of drug with DGL.
  • Cortisol, Prednisolone, and Related Corticosteroids (Oral and Topical) - Beneficial or supportive interaction with professional management, prevention or reduction of drug adverse effect; Licorice spares steroid by inhibiting metabolic degradation, potentiates anti-inflammatory effects and reduces adverse effects because lower drug doses permitted by combination.
  • Digoxin and Related Cardiac Glycosides - Minimal to mild adverse interaction - Vigilance necessary; Supratherapeutic doses of licorice may induce hypokalemia, which has been associated with potential digitalis toxicity (clinical significance low if drug and herb correctly prescribed and monitored with electrolyte monitoring). Monitor electrolytes and supplement with K+ and Mg+.
  • Potassium-Depleting Diuretics: Loop and Thiazide Diuretics - Minimal to mild adverse interaction - Vigilance necessary, adverse drug effect on herbal therapeutics with strategic concern; additive hypokalemic toxicity possible (in practice, reported cases all caused by unwitting or inappropriate self-adminstration of licorice-containing products). Avoid and advise patients to watch labels on candies, laxative, and other licorice-containing products.
  • Spironolactone - Interaction likely but uncertain occurrence and unclear implications; Complex interaction involving opposition of hypokalemia by drug at mineralcorticoid receptor and possible reduction in licorice adverse effect of hypertension (significance not established). Avoid until further data available.
  • Nitrofurantoin and Related Nitrofuram Antibiotics - Prevention or reduction of drug adverse effect; Reduction of gastroirritant side effects of drug (clinically less relevant due to replacement of nitrofurans with ciprofloxacin etc. Arguable same interaction as with aspirin, i.e., generic gastroprotective effect of herb). Co-administer DGL.


  1. Boon Heather, Smith Michael (2009) 55 Most Common Medicinal Herbs: The Complete Natural Medicine Guide Second Edition Institute of Naturopathic Education and Research, CCNM Toronto.
  2. Godfrey Anthony, Saunders Paul, Barlow Kerry, Gowan Matt (2011) Principles and Practices of Naturopathic Botanical Medicine, Advanced Botanical Medicine. V3 CCNM Press, Toronto.
  3. Shin YW, Bae EA, Lee B, Lee SH, Kim JA, Kim YS, Kim DH (Mar 2007) In vitro and in vivo anti allergic effects of Glycyrrhiza glabra and its components. Planta Med;73(3):257-61. PubMed PMID: 17327992.
  4. 4.0 4.1 Stargrove Mitchell Bebell, Treasure Jonathan, McKee Dwight L (2008) Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies.
  5. Brinker Francis (1997) Herbal Contraindications and Drug Interactions: Plus Herbal Adjuncts With Medicines, 4th Edition Eclectic Medical Publications.