Licorice is an herb that is native to the Mediterranean, southern and central Russia, and Asia Minor to Iran. Many species are now grown throughout Europe, Asia, and the Middle East. Licorice contains glycyrrhizic acid, which can cause complications when eaten in large quantities. Many “licorice” products manufactured in the U.S. actually don’t contain any licorice. Instead, they contain anise oil, which has the characteristic smell and taste of “black licorice.”
Licorice is taken by mouth alone or with other herbs for various digestive system complaints including stomach ulcers, heartburn, colic, and ongoing inflammation of the lining of the stomach (chronic gastritis). People also take licorice by mouth for many other conditions. There is some good evidence to support the use of specific licorice combination products for heartburn. But there is limited scientific evidence to support the use of licorice for other conditions.
Some people apply licorice to the skin for itchy, inflamed skin (eczema), psoriasis, or a skin condition characterized by brown spots (melisma). It may be helpful for itchy, inflamed skin, but there is no good scientific research to support its use for other skin conditions
Benefits of licorice
There are more than 300 different compounds in licorice, some of which have antiviral and antimicrobial properties.
Some clinical studies investigating the potential benefits of licorice have had promising results, particularly in the following areas:
Skin inflammation and infection
Licorice root may help treat eczema.
Eczema is the term for a group of skin conditions that, according to the National Eczema Association, affect over 30 million people in the United States.
Glycyrrhiza glabra extract, or licorice root extract, may be effective against bacteria that can infect the skin, according to a study in the Iranian Journal of Pharmaceutical Research.
The study showed antimicrobial activity against Staphylococcus aureus, which can cause skin infections, such as impetigo, cellulitis, and folliculitis. In this study, the researchers used extracts from the leaves and roots of the plant.
Stomach discomfort and ulcers
A double-blind study found that an extract containing glabridin and gangrene, which are flavonoids present in licorice root, was effective in relieving stomach discomfort. The extract reduced nausea, stomach pain, and heartburn.
Infection with bacteria called Helicobacter pylori can cause peptic ulcers in some people. Research suggests that a licorice extract may help kill H. Pylori bacteria. A clinical trial of 120 people found that the addition of licorice extract to the standard treatment significantly improved H. Pylori eradication.
Glycerine may help treat hepatitis C, a virus that infects the liver. Without treatment, hepatitis C can cause inflammation and long-term liver damage. Researchers have reported that glycyrrhizin demonstrates antimicrobial activity against hepatitis C in cell samples and may hold promise as a future treatment for this virus.
Doctors in Japan use an inject able form of glycyrrhizin to treat people who have chronic hepatitis C that does not respond to other treatments. The results of laboratory studies in Japan suggest that it may be helpful for this.
Some research suggests that licorice may help kill bacteria in the mouth that cause tooth decay.
However, although licorice has demonstrated antibacterial activity in the laboratory setting, human studies have not yet proven that it has any cavity-fighting power. Its ability to inhibit the growth of oral bacteria means that it does have potential as a future cavity treatment though.
Many people think of licorice as a sore throat remedy. A small study recruited people who were having a breathing tube inserted into their windpipe before surgery. Following its removal, the breathing tube can cause a postoperative sore throat, known as POST.
The researchers showed that gargling a licorice solution for 1–15 minutes before surgery was as effective as a ketamine gargle in reducing the incidence and severity of POST.
Another similar study found that solutions with a higher concentration of licorice were more effective than less concentrated solutions in improving POST.
Possible Side Effects
When taken as a supplement or tea, licorice root is considered safe and well tolerated in adults.
Licorice root supplements are only intended for short-term use. Consuming licorice daily for several weeks or longer can cause severe and potentially life-threatening side effects.
However, some side effects can occur if licorice root is taken in large quantities, and is likely the result of the excessive accumulation of glycyrrhizinic acid, which triggers an abnormal increase in the stress hormone cortisol. This can lead to a severe imbalance in the body’s fluids and electrolytes, manifesting with an array of possible symptoms, including
Extreme cases can lead to licorice poisoning and the development of kidney failure, paralysis, congestive heart failure, and pulmonary edema.11
Research shows that licorice root consumption during pregnancy or breastfeeding leads to adverse neurological effects in children later in life. As such, it should not be consumed by children, pregnant women, or nursing mothers.12 Licorice should also be avoided in people with kidney or liver dysfunction.
Side effects, toxicity, and interactions
Licorice can cause serious side effects if you take too much of it or use it for too long. It has an effect similar to aldosterone. Aldosterone is a hormone that causes your body to retain salt (sodium) and lose potassium.
Taking too much licorice can cause high blood pressure. This can be severe. It can cause the following symptoms:
You can even become poisoned from eating too much candy that contains real licorice or using licorice-containing tobacco.
You also shouldn’t take it if you drink a lot of alcohol. Women who are pregnant or breastfeeding also shouldn’t use this herb.
Don’t take licorice while fasting. Doing so can lead to a serious electrolyte imbalance.
Licorice can also interact with some medicines. Thiamine water pills (diuretics) may increase amount of potassium you lose when used with licorice. Licorice may also increase the effects of digitalis. This is because digitalis sensitivity is increased by low potassium levels.
Licorice may interfere with the effects of aldactone. This is a medicine used to treat high blood pressure. Talk with your healthcare provider before you take licorice.
You also shouldn’t take licorice if you take warfarin. It may increase your metabolism and decrease levels of warfarin.