Licorice: Benefits, Dosage, Contraindications

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Licorice is a perennial plant native to southeastern Europe and western Asia, growing up to 1 meter high, with a strong woody rhizome the thickness of a finger, brown on the outside, yellowish inside, and sweet-tasting, which earned it the name Glycyrrhiza formed from glycys, "sugar" and rhidza, "root." Licorice has been used since antiquity for asthma and ulcers. In Chinese medicine, it is considered a "phlegm-draining remedy," leading to its prescription for digestive inflammations and as an expectorant in respiratory tract conditions. Licorice contains several triterpenoid saponins (4-20%), the most studied of which is glycyrrhizin, known as glycyrrhizic acid or glycyrrhizinic acid, a mixture of potassium and calcium salts of glycyrrhetic acid. Glycyrrhizin is primarily absorbed after hydrolysis into glycyrrhetic acid. Other important constituents include: flavonoids (isoflavonoids, liquiritin, isoliquiritin, liquiritigenin, formononetin, glabridine, rhamnoliquiritin, neoliquiritin, and chalcones), phystosterols (beta-sitosterol, estriol, estradiol), polysaccharides, coumarins, and essential oils. Glycyrrhizin, the main active ingredient, can cause problems if consumed in large amounts. It may lead to a syndrome mimicking excess mineralocorticoid hormones, causing a state similar to hyperaldosteronism, where the body retains too much sodium and fluid. This can lead to symptoms such as water retention, edema (swelling), hypertension, hypokalemia (low potassium levels in the blood), and metabolic alkalosis (imbalance of pH in the body). Licorice is used for relieving digestive symptoms, including burning sensation and dyspepsia. It is also used as an expectorant (helping to expel mucus) in coughs associated with colds.

Other name(s) 

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Scientific name(s)

Glycyrrhiza glabra

Family or group: 

Plants

Active ingredients:

Glycyrrhizin


Indications

Rating methodology

EFSA approval.

Several clinical trials (> 2) randomized controlled with double blind, including a significant number of patients (>100) with consistently positive outcomes for the indication.
Several clinical trials (> 2) randomized controlled with double blind, and including a significant number of patients (>100) with positive outcomes for the indication.
One or more randomized studies or multiple cohorts or epidemiological studies with positive outcomes for the indication.
Clinical studies exist but are uncontrolled, with conclusions that may be positive or contradictory.
Lack of clinical studies to date that can demonstrate the indication.


Gastric Ulcer
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The anti-inflammatory, mucus-protecting, and anti-ulcer activities of licorice make it an interesting treatment for gastro-duodenal ulcers. Although these effects have been attributed to constituents glycyrrhizin and glycyrrhetic acid, deglycyrrhizinated licorice (DGL), containing < 3% glycyrrhizin, has also been studied and seems to produce the most promising results when used long-term. Licorice helps to transform non-specialized cells into mucus-producing cells and increases the manufacturing and release of mucus. A randomized placebo-controlled study (n = 100) showed that a Glycyrrhiza glabra root extract significantly decreased Helicobacter pylori infection compared to placebo, as evaluated by the 13C-urea breath test and the H. pylori antigen test in stools. In an uncontrolled trial of 32 patients with chronic duodenal ulcer, 3800 mg/day of deglycyrrhizinated licorice (divided into five doses) produced signs of healing in all cases and complete restoration of the mucosa in the majority of subjects. Although the treatment was continued for 24 weeks, significant improvement was observed in 56% of patients by the 12th week and in 78% by the 16th week. In contrast, a shorter 4-week trial in 96 patients with gastric ulcers did not yield the same positive results. Deglycyrrhizinated licorice combined with an antacid was as effective as cimetidine (200 mg three times a day plus 400 mg at night) after 6 weeks, according to a single-blind randomized trial in 100 volunteers with gastric ulcers. Both treatments continued to deliver similar results after 12 weeks and the relapse rates after tapering the two drugs were also similar. The German Commission E approves the use of licorice in the treatment of gastric and duodenal ulcers.

Posologie

posologieOral route: root

posologie100 - 900 mg

formulationpowder, tea/infusion, mother tincture, dry extract


Eczema
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The application of gel formulations containing 1% or 2% licorice root extract three times a day for two weeks appears to reduce erythema, edema, and itching. The 2% gel is more effective than the 1% gel. The anti-inflammatory effect induced by glycyrrhetic acid provides a theoretical basis for its use as a topical anti-inflammatory agent (similar to hydrocortisone) in the treatment of dermatitis. In practice, glycyrrhetic acid has been used to potentiate the effects of mild steroids (such as hydrocortisone) to increase pharmacological effects without the need for more potent corticosteroids. It is assumed that increasing corticosteroid activity in this manner will not lead to an increase in adverse effects; however, no study has confirmed this presumption yet. A study comparing the effects of ointments containing hydrocortisone and glycyrrhetic acid on dermatitis revealed that hydrocortisone was generally superior in acute and infantile eczemas, while glycyrrhetic acid was superior in chronic and subacute conditions. It should be noted that glycyrrhetic acid might have more pronounced anti-inflammatory effects than glycyrrhizin. Glycyrrhetic acid is not present in licorice but is produced in the gastrointestinal tract from glycyrrhizin; therefore, it is unclear whether topical preparations containing pure licorice can produce the same effects.

Posologie

posologieTopical route: root

formulationgel, ointment, cream


Canker Sores
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Clinical research shows that applying an oral patch containing licorice at a dosage of 0.015-0.229 mg/kg for 16 hours each day for 8 days does not affect ulcer healing time but reduces ulcer size and post-stimulus pain compared to placebo. A small clinical study also shows that applying bioadhesive hydrogel patches containing 1% licorice extract reduces pain, necrosis diameter, and inflammatory halo of recurrent canker sores compared to baseline. Mouth rinses containing licorice have also been used. A clinical study shows that swishing a solution of diphenhydramine and 5% licorice extract in the mouth for about 3 minutes, four times a day, until the canker sores are healed, reduces the average healing time compared to a solution containing only diphenhydramine. Pain was reduced by up to 69% more in people using the licorice extract. Preliminary clinical research shows that gargling with warm water containing 200 mg of deglycyrrhizinated licorice powder four times a day for 7 days improves pain in 75% of patients on the first day and achieves complete healing in 75% of patients by the third day.

Posologie

posologieOral route: root

formulationgel, patch, mouth rinse


Hepatitis
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In some preliminary clinical research, a specific intravenous preparation containing glycyrrhizin seems to reduce mortality due to viral hepatitis by about 50%. Other clinical research suggests that this same product reduces serum alanine aminotransferase (ALT) in patients with hepatitis C but does not improve hepatitis C viral RNA levels. Used long-term, this preparation appears to reduce the risk of hepatocellular carcinoma in patients with hepatitis C, compared to long-term use of other supplements like vitamin K. This product has been used at different doses: 40 or 100 mL, containing 2 mg glycyrrhizin, 1 mg cysteine, and 20 mg glycine per ml of solution, administered daily for 4-8 weeks, other dosages have been used, intravenously. Other research shows that this preparation reduces ALT, aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGT) in patients with hepatitis B virus. To date, oral licorice has not been evaluated for this purpose.

Posologie

posologieIntravenous route: root

posologie600 - 900 mg

formulationpowder, mother tincture, dry extract


Digestive Disorders
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Licorice has been evaluated in combination with other plants, for dyspepsia. The most studied product is Iberogast which contains, in addition to licorice, a tincture of bitter candytuft as well as tinctures of angelica root, German chamomile flowers, caraway seeds, milk thistle fruit, lemon balm leaves, peppermint leaves, and celandine. A meta-analysis of studies using the Iberogast product shows that taking 1 mL orally three times daily over a period of 4 weeks reduces the severity of acid reflux, epigastric pain, cramps, nausea, and vomiting compared to placebo. The EMA recommends licorice as a traditional herbal medicinal product for the relief of digestive symptoms, including burning sensation and dyspepsia.

Posologie

posologieOrally: root

posologie100 - 900 mg

formulationpowder, herbal tea/infusion, mother tincture, dry extract


Synergies


Gastritis
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In Germany, Commission E emphasizes that clinical trials have demonstrated the healing effect of glycyrrhizin and glycyrrhetinic acid on gastric ulcers and chronic gastritis.

Posologie

posologieOrally: root

posologie100 - 900 mg

formulationpowder, herbal tea/infusion, mother tincture, dry extract


Asthma
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In relation to the antiallergic effects of licorice, it is traditionally recommended for the treatment of allergic conditions such as asthma and dermatitis; however, clinical research is required.

Posologie

posologieOrally: root

posologie600 - 900 mg

formulationpowder, mother tincture, dry extract


Respiratory infections
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Animal studies show a reduction in viral activity for herpes simplex virus, encephalitis, and influenza A viral pneumonia; and in vitro studies reveal antiviral activity against HIV-1, SARS-related coronavirus, respiratory syncytial virus, arboviruses, vaccinia virus, and vesicular stomatitis virus. However, until controlled studies are available, the clinical efficacy of this treatment remains unknown. Licorice increases mucus production in the respiratory tract and exerts an expectorant and antitussive effect. Combined with its anti-inflammatory, antiviral, and possibly immune-stimulating effects, it is a popular treatment for infections of the upper and lower respiratory tracts. In practice, it is often used to treat cough and bronchitis.

Posologie

posologieOrally: root

posologie600 - 900 mg

formulationpowder, mother tincture, dry extract


Stomatitis
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Licorice is traditionally indicated for inflammations of the ENT pathways: laryngitis, sinusitis, stomatitis, due to its anti-infective and anti-inflammatory action.

Posologie

posologieOrally: root

posologie600 - 900 mg

formulationpowder, mother tincture, dry extract


Improve adaptability
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Traditionally, licorice is considered an "adrenal tonic", most likely due to its ability to slow the breakdown of cortisol. It may be beneficial for patients undergoing allostatic load due to chronic stress and therefore unable to organize a healthy response to stress. This phenomenon is also known as adrenocortical insufficiency. There are no controlled trials to determine its effectiveness in this situation. It is questionable whether this effect is desirable in patients who do not suffer from adrenocortical insufficiency and for whom increased cortisol levels can prove problematic. Chronically elevated cortisol levels have been associated with desensitization of the hypothalamic-pituitary-adrenal axis, insulin resistance, depression, and immunosuppression. In the early stages of stress, increased cortisol levels trigger negative feedback mechanisms to keep stress under control and, consequently, short-term use may be justified, but it is unlikely to be beneficial unless there is some adrenocortical insufficiency.

Posologie

posologieOrally: root

posologie600 - 900 mg

formulationpowder, mother tincture, dry extract


Properties


Anti-inflammatory

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Glycyrrhetic acid, a compound in licorice, works by increasing cortisol levels and other steroid hormones, thus contributing to its anti-inflammatory effects. It inhibits certain liver enzymes, prolonging cortisol activity. Licorice is studied for enhancing steroid effects. It also inhibits eicosanoid production and NF-kB transcription factor activation. Furthermore, studies show its effectiveness against inflammation in various experimental models, including asthma, colitis, and edema.

Usages associés

Gastritis, Hepatitis, Gastric Ulcer, Stomatitis, Canker Sores

Antiviral

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Oral and injectable forms of licorice, including glycyrrhizin and glycyrrhizic acid, have demonstrated antiviral activity against various viruses. In humans, these compounds reduce liver damage related to hepatitis B and C viruses. Animal studies show decreased viral activity for herpes simplex, encephalitis, and pneumonia caused by the influenza A virus. In vitro research also indicates effectiveness against HIV-1, SARS coronavirus, respiratory syncytial virus, various arboviruses, enteroviruses, coxsackievirus, and vesicular stomatitis virus. Proposed antiviral mechanisms include reducing transport to the cell membrane and inhibiting viral membrane fusion, as well as activating immune responses like gamma interferon.

Usages associés

Respiratory Infections, Bronchitis

Mucolytic

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Initial research on licorice's mucoprotective properties led to the development of drugs such as carbenoxolone and enoxolone to treat gastric and esophageal ulcers. These drugs appear to work by increasing blood flow in the mucosa and mucus production, and modifying gastric prostanoid synthesis. Animal studies show that licorice, particularly in deglycyrrhizinated form, promotes healing by stimulating mucus production. Besides its gastrointestinal effects, licorice has shown expectorant and antitussive properties, possibly related to the stimulation of tracheal mucus secretion and tracheal relaxation.

Usages associés

Bronchitis, Cough

Gastroprotective

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Glycyrrhetic acid and licorice polysaccharides have shown an ability to inhibit the Helicobacter pylori strain in vitro studies. These compounds also inhibit H. pylori adhesion to human gastric mucosa. Licorice may also affect prostaglandin metabolism, suggesting a beneficial effect on gastro-duodenal ulcers. In vivo studies indicate that water-based licorice extract reduces ulcer size similarly to famotidine. Deglycyrrhizinated licorice (DGL) appears to speed ulcer healing without the side effects of carbenoxolone, a semi-synthetic derivative of glycyrrhetic acid.

Usages associés

Gastric Ulcer, Digestive Disorders

Antibacterial

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Licorice is traditionally used as an antimicrobial, with in vitro research showing it possesses antifungal activity and activity against both Gram-positive and Gram-negative bacteria. Licorice contains constituents like glabridine, glabrol, and 3-hydroxyglabrol with in vitro antimicrobial activity. Glabridine has been identified as a potentially active agent against Mycobacterium tuberculosis, responsible for tuberculosis. Licorice extracts in water and ether have shown antibacterial activity against E. coli, B. subtilis, E. aerogenes, K. pneumoniae, and S. aureus. In children at high risk of dental cavities, a licorice extract lollipop reduced the number of Streptococcus mutans, a bacteria involved in cavity formation.

Usages associés

Respiratory Infections, Canker Sores, Stomatitis

Antiallergic

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Licorice components, glycyrrhetic acid, and liquiritigenin, show significant anti-allergic effects. They relieve IgE-induced allergic reactions, reduce anaphylactic reactions, and scratching behavior in mouse models. In a mouse model of asthma, glycyrrhizin decreased lung inflammation and levels of interleukins and IgE. These results suggest therapeutic potential for treating allergic conditions like asthma and dermatitis, although further research is necessary to confirm these effects.

Usages associés

Asthma, Eczema

Hepato-protective

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Licorice extract, or glycyrrhizin, has a positive effect on rat liver, increasing the activity of important hepatic enzymes like CYP3A, CYP2B1, and CYP1A2. In rats with liver damage, it decreases liver damage indicators and improves levels of essential proteins (albumin and globulin). It also stimulates antioxidant defenses and protects against lipid peroxidation. Preliminary human studies suggest this extract could help reduce markers of liver damage in people with non-alcoholic fatty liver disease.

Usages associés

Hepatitis

Antifungal

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Licochalcone A and glabridine, components of licorice, have shown antifungal activity against Candida albicans. At high doses, they inhibit hyphae growth, with licochalcone A also reducing biofilm formation. However, it is important to note that these components may be toxic to oral epithelial cells at higher concentrations.


Estrogenic Action

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Licorice can act as both an anti-estrogenic and estrogenic agent. Preliminary research shows it limits the growth of estrogen-sensitive breast cancer cells. However, its estrogenic effect can vary depending on the concentration. Glabridine, a licorice isoflavone, stimulates cell growth at low concentrations but shows an antiproliferative effect at higher concentrations. Licorice also decreases testosterone production, likely by inhibiting certain key enzymes. It also reduces elevated prolactin levels in men.


Antidepressant

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Licorice flavonoids, such as glabridine, have shown an ability to dose-dependently inhibit serotonin (an important mood neurotransmitter) reuptake in vitro. However, effects on animals suggest that the impact might be more on norepinephrine and dopamine. In rats, licorice showed an antidepressant effect similar to some drugs, but via increased norepinephrine and dopamine levels rather than serotonin. Licorice might act by inhibiting monoamine oxidase (MAO inhibitors are used in the treatment of certain depressions).


Safety dosage

Adult from 18 year(s): 160 mg - 900 mg (dry extract)

- Herbal tea: 1.5 to 2 g of ground plant substance in 150 ml of boiling water as an infusion 2 to 4 times a day or 1.5 to 2 g of ground plant substance in 150 ml of water as a decoction 2 to 4 times a day. Drink a cup after meals.a - Dry extract: 32 mg 2 to 3 times a day for oral use in dyspepsia and 3 times 200 to 300 mg per day for other indications. - Powder: 3.6 to 6 g corresponding to 100 -240 mg of glycyrrhizin. Caution with the use of licorice-based products containing glycyrrhizin orally in large quantities for several weeks, or in smaller quantities for longer periods. In otherwise healthy individuals, daily consumption of glycyrrhizin for several weeks or more may cause serious adverse effects, including pseudo-hyperaldosteronism, hypertensive crisis, hypokalemia, cardiac arrhythmias, and cardiac arrest. Doses of 20 grams or more of licorice, containing at least 400 mg of glycyrrhizin, are more likely to cause these effects. However, smaller quantities have also caused hypokalemia and associated symptoms when taken for months or years. In patients with hypertension, cardiovascular or renal problems, or high salt consumption, as little as 5 grams of licorice product or 100 mg of glycyrrhizin per day can cause serious adverse effects.


Interactions

Médicaments

Antihypertensive: moderate interaction

High-dose licorice intake over a prolonged period may result in increased blood pressure, thereby reducing the effectiveness of the medication. Caution - monitor blood pressure when high-dose licorice preparations are taken for more than 2 weeks.

Antiplatelets/Anticoagulant: weak interaction

Licorice has been documented to have an anticoagulant effect, so high amounts should be avoided in patients taking any form of anticoagulant medication.

Corticosteroid: weak interaction

Case reports suggest that concurrent use of licorice and oral corticosteroids, such as hydrocortisone, may potentiate the duration of activity and increase corticosteroid blood levels.

Diuretics: weak interaction

Excessive use of licorice could worsen potassium loss induced by diuretics. Initiation of potassium supplementation or an increase in the dose of potassium supplementation may be necessary in some patients.

Midazolam: moderate interaction

In humans, glycyrrhizin appears to moderately induce the metabolism of midazolam. It should be used with caution in individuals taking midazolam.


Precautions

Breastfeeding woman: avoid

Insufficient data.

Hormone-sensitive condition: avoid

Licorice may have estrogenic effects. Women with hormone-sensitive conditions should avoid using licorice. Some of these conditions include breast cancer, uterine cancer, ovarian cancer, endometriosis, and uterine fibroids.

Child: avoid

Use in children and adolescents under 18 years has not been established due to the lack of adequate data.


Contraindications

High blood pressure: prohibited

The mineralocorticoid effects of licorice can increase blood pressure. Patients with hypertension should avoid consuming excessive amounts of licorice.

Renal insufficiency: prohibited

The mineralocorticoid effects of licorice may worsen renal function.

Pregnant woman: prohibited

Licorice has abortifacient, estrogenic, and steroidal effects. It may also induce uterine stimulation. Heavy consumption of licorice, equivalent to 500 mg of glycyrrhizin per week (about 250 grams of licorice per week), during pregnancy appears to increase the risk of premature birth.

Hypertension: prohibited

Licorice-induced hypokalemia may worsen hypertension. The mineralocorticoid effects of licorice can cause hypokalemia.

Hypokalemia: prohibited

The mineralocorticoid effects of licorice can reduce serum potassium levels and exacerbate hypokalemia.