Licorice Uses and Plant Monograph

Made famous for its role in flavoring candy, licorice root is a powerful herb that people have used for thousands of years in Asia, Africa, India, and North America. Shennong’s Classic of Materia Medica, published around 4,000 years ago in what is now China, mentions licorice as medicine, and licorice has been a central part of many Traditional Chinese herbal formulas ever since. It’s theorized that monks probably brought licorice to Europe in the Middle Ages.

While Glycyrrhiza glabra (licorice) and G. uralensis (Chinese licorice) are the species used in Europe and Asia, Glycyrrhiza lepidota (American licorice) is a species of licorice native to North America that has been used as both food and medicine for thousands of years.

Energetics

Licorice root is overtly sweet and demulcent. The botanical genus name for licorice, Glycyrrhiza, means “sweet root” in Greek. This is an apt name for a root that is many times sweeter than sugar cane (Saccharum spp.).

The sweet and moistening characteristics of licorice root are often used to nourish and build the body when there are signs of weakness and dryness.

In Traditional Chinese Medicine (TCM), licorice is often referred to as the “peacekeeping herb”: it’s frequently added to harmonize and improve the flavor of formulas. Due to this extensive use, it is one of the most commonly used herbs in TCM.

For the Skin

Soothing demulcent qualities coupled with a powerful ability to modulate inflammation make licorice an ally both externally and internally to support skin health.

In one study, a topical cream made with a combination of licorice, willow bark, and gentian was shown to be more effective than placebo and just as effective as hydrocortisone cream at reducing skin inflammation associated with atopic dermatitis.¹

Hot, painful, and irritated throats from upper respiratory infections are easily soothed with licorice root. It’s commonly found in sore throat tea formulas, like Traditional Medicinal’s well-known Throat Coat tea.

When I have a scratchy or sore throat, licorice root tea is the first thing I reach for. The sweet taste and thick consistency of licorice seem to magically erase a dry and scratchy sore throat. When I have a cold, I keep a thermos of licorice tea on my bed stand to easily access when I wake up with an irritated throat.

Besides soothing sore throats, licorice is commonly used as a pectoral (chest) herb. It soothes coughs, especially those dry and irritating coughs that can keep you up all night. Since sore throats and coughs tend to come together, licorice is a wonderful herb to reach for in these conditions. Add in the antiviral and antibacterial properties of licorice, and you’ve got an incredibly useful herb for common upper respiratory infections.

Licorice can also help prevent sore throats that are caused by surgery. A 2019 review showed that using a topical application of licorice before surgery “appears significantly more effective than non-analgesic methods for preventing postoperative sore throat.”² Simply gargling with licorice tea was shown to prevent sore throats associated with intubation.³ Licorice lozenges have also been shown to help smokers prevent post -operative sore throat pain.⁴

A review of licorice and the component glycyrrhizic acid showed that it can potentially reduce inflammation associated with allergic asthma.⁵

Heals Digestion

Licorice is famously used to heal ulcers and to address digestive heat and bacterial imbalances like those of Helicobacter pylori(H. pylori).

In a randomized, double-blind, placebo-controlled study, 140 patients with H. pylori infections were divided into two groups. One group received a beverage of fermented milk with the probiotic Lactobacillus paracasei and licorice root, and the other group received a placebo. Those who received the herbal milk showed reduced density of H. pylori and had significant improvement in inflammation levels and gastrointestinal symptoms compared to those who received the placebo.⁶

The soothing demulcent qualities of licorice root can also be helpful for addressing hot, irritable pain in the stomach and bowels that isn’t associated with ulcers. Additionally, licorice can also work as a mild laxative for people with dry, hard stools.

Antiviral and Antibacterial

Licorice and its extracts have been shown to be active against a variety of viruses, including hepatitis viruses, herpes simplex virus, viral pneumonia, and viral upper respiratory infections.^7,8,9

The polysaccharides in licorice have been shown to inhibit pathogens that are associated with gum disease and ulcers from adhering to cell walls, leading researchers to conclude that water extracts of licorice are “potent tools for a further development of cytoprotective preparations with anti-infectious potential.”¹⁰

After the initial outbreaks of severe acute respiratory syndrome (SARS) in the early 2000s, many studies looked at the potential of herbal medicines to inhibit the SARS-associated coronavirus. One study that looked at several compounds found that glycyrrhizin, an extract of licorice root, was the most active in inhibiting the replication of the SARS-associated coronavirus.¹¹

Researchers are currently studying licorice root and its extracts for their effect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19).¹² We know that licorice can interfere with COVID-19 pathogenesis via “inhibition of virus replication and entry to its host cells,” but no human clinical trials have been completed.¹³

While the roots of licorice are the most commonly used part, the leaves have also been shown to have antibacterial potential against gram-positive bacteria.¹⁴

Improves Oral Health

As mentioned above, studies show that licorice root is active against pathogens like Porphyromonas gingivalis that can cause gum disease,¹⁵ An in vitro study has also shown licorice’s ability to address bacterial infections that can cause tooth decay.¹⁶

In addition to its antimicrobial properties, the roots of licorice can be made into a practical toothbrush, which makes it an ideal herb for oral health. The end of the root is chewed until softened into bristles, which are then used to brush or scrub the teeth and the gum line. My husband has been using licorice root as his primary toothbrush for many years, and he always gets a great report at his dental hygiene visits.

What is DGL?

Because of its mineralocorticoid action, in large doses licorice root can cause some people to retain water and thus develop hypertension. Deglycyrrhizinated licorice (DGL), is a processed form of licorice in which glycyrrhizin has been removed. This form of licorice can be taken in higher doses without the undesirable effects of water retention or hypertension. DGL lozenges are commonly used for soothing mucous membranes, such as a sore throat or inflamed digestive tissues. DGL is especially useful for soothing and protecting the inflamed lower esophagus that people with gastroesophageal reflux disease (GERD) or heartburn experience.

When using licorice for its antiviral properties, the whole root must be used rather than DGL products.

As an Adaptogen

Licorice has adaptogenic qualities, which means it helps the body adapt to stress and normalize physiological functions. Licorice is specifically helpful for people with adrenal insufficiency and low cortisol levels: the root helps the body spare cortisol by inhibiting its conversion to cortisone. Herbalists often incorporate Licorice into adaptogenic formulas.

Cancer

Researchers are beginning to examine the potential role of licorice in fighting cancer. One in vitro study showed licorice’s antiproliferative properties against the PC-3 human prostate cancer cell line.¹⁷

(Source.)

Plant Preparations

Licorice can be made into teas or decoctions, tinctures, or a powder for capsules or other applications. It can also be made into a mouthwash, and the whole dried roots can be fashioned into a toothbrush.

Chewing on licorice roots is sometimes recommended as a replacement habit for people who want to stop smoking.

Licorice is commonly added in small amounts to herbal formulas rather than being used as a simple.

Interestingly, most of the licorice produced in the world today is used as a tobacco-flavoring agent.

Not all licorice candies have licorice in them—many have artificial flavoring.

Dosage Suggestions

• Powder: 1–9 grams per day
• Tea/Decoction: 1–9 grams per day
• Tincture (dried root): 1:5, 30% 2–3 mLs, three times a day

 

 

Special Considerations

Licorice, especially when taken in large amounts for long periods of time, can cause water retention and thus increase blood pressure. Some people seem to be more susceptible to this than others.

Here are some safe practice suggestions for licorice:

• Take licorice in smaller doses and as part of a larger herbal formula.
• Avoid taking more than 9 grams of licorice per day for an extended period of time.
• If you decide to take larger dosages of licorice, regularly check your blood pressure and discontinue use if you notice any unusual water retention in your body.
• Avoid use of licorice if you currently have high blood pressure and/or edema (swelling).

Because it inhibits the breakdown of cortisone, Licorice may also interact with corticosteroid medications by increasing their effect. If you are on corticosteroid medication, then it would be best to work with someone experienced in using these two substances together.

Many of the case studies that included unwanted effects of licorice were reported in people consuming large amounts of licorice candy.

Licorice root is not recommended during pregnancy, and its safety has not been established for use during lactation.

Written by Rosalee de la Forêt

Rosalee de la Forêt is an herbalist and author of the bestselling book Alchemy of Herbs: Transform Everyday Ingredients Into Foods & Remedies That Heal and co-author of Wild Remedies: How to Forage Healing Foods and Craft Your Own Herbal Medicine. She’s a registered herbalist with the American Herbalists Guild. Explore Rosalee's website and podcast. All content and photos in this article are © Rosalee de la Forêt.