Liquorice, Glycyrrhiza glabra
- Indications with possible efficacy:
- Indications with possible, but poorly documented efficacy:
Stomach or duodenal ulcer
- Other indications with no proof of efficacy:
Boost the immune system
Respiratory tract infections (tonsillitis, pharyngitis)
- Risk of Drug Interactions: High
- Adverse Effects: Moderate
Parts of the plant used: roots, rhizomes and stolons (aerial stems)
The licorice plant is a small shrub that measures about 1.5 meters. It grows best in warmer climates and is mainly found in southern Europe, Asia and North Africa. Glycyrrhizic acid, which is one of the main active components in licorice, is responsible for some of its therapeutic effects. To prevent adverse reactions, some licorice extract does not contain glycyrrhizin and is known as "deglycyrrhizinated" licorice.
Traditionally, licorice has been used as a flavouring agent.
Directions for use
- Dyspepsia and stomach or duodenal ulcers
Tablets standardized to contain 20 % glycyrrhizic acid - 250 to 500 mg, 3 times a day. The safety of using licorice for more than 4 to 6 weeks has not been established.
Deglycyrrhizinated licorice tablets - 380 to 760 mg, 3 times a day, 20 minutes before meals.
- Adverse effects
There are few adverse effects associated with usual doses of licorice.
High doses of glycyrrhizic acid may cause sodium and fluid retention and low potassium levels which can lead, among other things, to hypertension, arrhythmia, headache, muscle weakness, respiratory failure and renal failure. Deglycyrrhizinated licorice may lower libido and worsen erectile dysfunction in men.
Use with caution in patients with hypertension, cardiovascular disease, heart failure and renal failure.
Licorice is not recommended for those taking oral anticoagulants, antiplatelets or anti-inflammatories. The same recommendation applies to those using corticosteroids, digoxin or powerful laxatives. Before using licorice, speak to your pharmacist to see whether it is compatible with the drugs you are presently taking.
- Pregnancy and breastfeeding
Licorice is not recommended during pregnancy. It appears to have a mild estrogenic effect and could cause a miscarriage. There is no reliable information about the safety of licorice when breastfeeding.
In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.
Medicinal plant contents vary naturally from plant to plant - just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.
For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.
- Natural Medicines Comprehensive Database, Therapeutic Research Faculty, 2010
- Passeportsanté.net. Réglisse. www.passeportsante.net
- Natural Therapeutics Pocket Guide, 2000-2001
- Rotblatt M. & Ziment I. Evidence-Based Herbal Medicine, Hanley & Belfus, 2002
- The Review of Natural Products, 6th Edition, 2010
- Health Canada, Natural Products Database
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