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Effects of Licorice Root on Tooth Decay, Gum Disease, and Health

Linda Crampton has an honors degree in biology. She is interested in chemicals from other organisms and their benefits to the human body.

Licorice root is edible, sweet, and delicious.

Licorice root is edible, sweet, and delicious.

A Potentially Useful Root

Licorice is a perennial herb in the legume family—the same family to which peas and beans belong. The root of the plant is edible and is both sweet and flavorful. In addition to being eaten whole and chopped, it can be boiled in water to make an extract. This extract can be concentrated and added to foods and drinks or used to make candy, sometimes in combination with other substances. The word "licorice" is used to refer to the plant, the extract, or the candy. In the UK, the word is spelled "liquorice".

Licorice has been a popular food additive since ancient times. It's also had a long use in traditional medicine. Today it's claimed to have many health benefits. There is preliminary evidence supporting some of these claims, but for others the evidence is mixed. Research suggests that the substance may be beneficial for oral health, however. It appears to inhibit the activity of certain bacteria that cause tooth decay and gum disease. Dentist-recommended procedures should be followed to maintain healthy teeth and gums. The possible benefits of licorice when used in addition to these procedures are interesting to explore, however.

Although the future role of licorice in oral hygiene looks promising, there are potential dangers to ingesting the root or extract, especially for some people. Anyone who eats or drinks the products or who uses them in the hope of improving dental hygiene needs to be aware of these dangers.

The Licorice Herb

The scientific name of the licorice herb is Glycyrrhiza glabra. It's a member of the family Fabaceae, which is also known as the Leguminosae or the Legume family. Peas, beans, lentils, and peanuts also belong to the family. The members of the family have compound leaves and a fruit in the form of a legume or a pod.

Licorice is native to southern Europe and some parts of Asia. It's also grown in other areas as a garden plant. Like other legumes, the plant has nodules on its roots that contain bacteria that fix nitrogen. "Fixing" is the process of converting atmospheric nitrogen into nitrogenous compounds that plants and other organisms can use.

Glycyrrhiza glabra is known as licorice or the licorice herb in everyday English. The plant shouldn't be confused with Helichrysum petiolare, which is known as the licorice plant and belongs to the family Asteraceae. This plant is not edible.

Antibacterial Compounds in Licorice Root

Two antibacterial chemicals in licorice root are licoricidin and licorisoflavan. An international research team has made some interesting discoveries that link these chemicals to oral health. The results were published by the American Chemical Society. A link to the relevant article is provided in the first reference below.

The researchers found that each chemical strongly inhibited two major tooth decay bacteria—Streptococcus mutans, which is the most important bacterium involved in human tooth decay, and Streptococcus sobrinus. The chemicals also had a major inhibitory effect on two common gum disease bacteria—Porphyromonas gingivalis and Prevotella intermedia. In addition, the licoricidin moderately inhibited a third bacterium, Fusobacterium nucleatum, which is often associated with periodontal disease.

The scientists used an extract made from licorice root and tested it on bacteria that were placed in lab containers. Hopefully, the chemicals obtained from the root will have the same effect in our mouths as they did in the lab. If they do, we'll need to find out how much of the root needs to be used and how long it will have to stay in contact with oral bacteria to inhibit their growth.

Streptococcus mutans is a common cause of tooth decay.

Streptococcus mutans is a common cause of tooth decay.

Trans-Chalcone and Oral Bacteria

Researchers at the University of Edinburgh examined another antibacterial compound in licorice. The researchers tested the effect of a chemical called trans-chalcone on oral bacteria. The news release from the university refers to the potential benefit of natural products for oral health, but it also says that the trans-chalcone was "related" to chemicals in licorice root. This presumably means that a natural substance was slightly altered. Even before the experiment was performed, scientists knew that licorice root contains chemicals called chalcones and that these have antibacterial properties.

The researchers found that trans-chalcone blocks an enzyme needed by Streptococcus mutans when it forms biofilms. A biofilm is a collection of bacteria embedded in a protective polysaccharide layer. Biofilms in the mouth are known as plaque. Bacteria in biofilms are much harder to attack than those outside biofilms.

The research is very interesting, but once again it was performed in lab equipment instead of in the human mouth. Lab results are sometimes the same as the results in humans, but not always. Two problems with the use of licorice products for oral health are that materials in the mouth are diluted by saliva and they are quickly swallowed. Researchers at the University of Michigan may have a solution to this problem. They used a licorice lollipop in their research project. Since the lollipop was repeatedly sucked, potentially beneficial compounds were continually added to the mouth.

The research linking licorice to oral health described in this article was performed by scientists from reputable organizations. I have been unable to find reports of more recent studies than the ones described. This doesn’t mean that the discoveries made so far are invalid, however.

Licorice Lollipops and Oral Bacteria

In a pilot study, researchers at the University of Michigan gave a small group of children sugar-free lollipops that contained a licorice extract. They found that when children at high risk for cavities sucked two lollipops a day for three weeks, the level of Streptocococcus mutans in their saliva was greatly decreased. The bacterial population stayed at a decreased level for twenty-two days after the last lollipop was sucked and then began to increase again.

In another pilot study using lollipops, the licorice extract in the candy was rich in a substance called glycyrrhizol A. In this study, people of different ages sucked two lollipops a day for ten days. Many of the people (but not all of them) showed a big decrease in Streptococcus mutans in their saliva after the treatment.

Other research suggests that licorice root extracts can reduce the inflammation involved in periodontal disease and even inhibit the bone loss that occurs in the disease. They could be very helpful for improving oral health.

The amount of licorice root that can be safely tolerated depends on body weight as well as pre-existing health conditions and life stage. Anyone with questions about the use of the substance in their own life should consult a doctor. Pregnant and nursing women and people with estrogen-sensitive diseases shouldn’t eat licorice.

Potential Dangers of Licorice Products

Black and red licorice candy rarely contain the extract from the plant. They’re generally flavored with anise oil and/or artificial flavors instead of licorice. They contain a lot of sugar too, which is bad for oral health. Both licorice and anise seeds get much of their flavor from a chemical called anethole.

Real licorice candy and products are available, but caution is needed before a person starts eating or drinking these. Licorice affects blood pressure by increasing the amount of a hormone called aldosterone in the blood. Aldosterone stimulates water and sodium reabsorption in the kidneys and also stimulates potassium excretion. An excessive amount of aldosterone raises blood pressure and may lead to heart problems. It may also cause muscle weakness.

Licorice contains isoflavones, which act as phytoestrogens. Phytoestrogens are thought to act like estrogen in our body. Both males and females have this hormone, though females have far more than men until menopause. (Males and females also have testosterone in different amounts.) Phytoestrogens may affect the function of some of our real hormones. Some evidence suggests that licorice lowers the testosterone level in men. Another potential problem with ingesting the substance is that it may interfere with the action of certain medications.

Black licorice candy may not contain real licorice extract and may not be tooth-friendly.

Black licorice candy may not contain real licorice extract and may not be tooth-friendly.

The European Scientific Committee on Food advises that regular glycyrrhizin doses of 100 mg/day present a risk to health, and advocate a safe average daily intake of no more than 10 mg/person/day. This is an amount equivalent to less than half a cup of liquorice tea or just 6 g of liquorice confectionary daily.

— Allcock, E. and Cowdery, J, British Medical Journal

The consensus of health experts seems to be that for most people licorice is safe when used occasionally and in moderate amounts to flavor foods or drinks or to eat as a treat. The maximum amount that is safe depends on an individual's state of health. As mentioned above, some people shouldn't eat the substance at all.

People over forty who have heart disease seem to be most susceptible to health problems caused by the root or extract. Even children may be adversely affected by licorice, however.

Several researchers say that up to five or six grams of licorice a day is probably safe for healthy adults. They also say that five grams a day may be too much for people who have heart disease or kidney problems, however. It seems advisable to use considerably less than this amount when using the substance for oral health, even when a product is being used as a mouthwash.

Healthy people should follow the recommended limits above and should also look at the WHO recommendations below, which are slightly different. People who have health problems such as heart or kidney problems or high blood pressure should ask their doctor about the advisability of eating, drinking, or using licorice products. It's a good idea to consult a doctor about licorice intake in children, too.

The World Health Organization (WHO) recommends a maximum intake of 2 mg glycyrrhizic acid per kg of body weight per day. The organization says this intake is unlikely to cause adverse effects, although negative effects are still possible in sensitive people. Licorice is assumed to contain 0.2% glycyrrhizic acid by weight.

Deglycyrrhizinated Licorice

Glycyrrhizin (or glycyrrhizic acid) is the main chemical responsible for the sweetness of licorice. It also seems to be responsible for many of the potentially dangerous effects of the substance. A boy described in the literature ate twenty real licorice candies a day for four months before seizures started. This gave him a daily dose of 2.88 mg of glycyrrhizic acid per kg of body weight, which is significantly higher than the upper limit recommended by the World Health Organization.

Deglycyrrhizinated licorice products (DGL products) are available in stores. These products have had their glycyrrhizin removed and may therefore be safe. It's not known if ingesting DGL instead of whole licorice eliminates every dangerous effect or if they have all of the health benefits that are attributed to the whole substance.

A Licorice Poll

Oral Health Now and in the Future

Anything that decreases tooth decay and gum disease and is also safe to use would be a great addition to an oral hygiene routine recommended by a dentist. Oral hygiene products that are flavored with licorice root or extract already exist, but it’s unknown if they contain enough of the helpful chemicals to affect bacteria in the mouth.

Perhaps in the future we’ll be able to buy mouthwashes containing effective amounts of the antibacterial chemicals from licorice root (assuming their ability to fight oral bacteria is confirmed by more research). We may also be able to buy toothpaste and chewing gum that contain useful amounts of the chemicals. Until then, we need to be careful when eating or drinking products containing them. It would be a good idea to keep track of the amount of licorice that we’re ingesting or using in order to prevent any health problems from developing.


  • Dried licorice root fights oral bacteria from the American Chemical Society
  • Trans-chalcone and oral bacteria from the University of Edinburgh
  • Licorice lollipops and oral health from the European Archives of Paediatric Dentistry (abstract only)
  • An in-vitro (lab equipment) study of licorice’s effects on oral bacteria from the Journal of International Oral Health
  • Black licorice warning from the FDA (Food and Drug Administration)
  • Licorice manufacturers encouraged to state daily limit of consumption from the EurekAlert news service
  • Side effects and safety of the substance from WebMD
  • Hypertension (high blood pressure) induced by liquorice tea: a summary from BMJ Case Reports
  • Dangers of overconsumption of licorice from Medical Xpress

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2012 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on July 02, 2017:

Hi, Kathy. Yes, licorice candy can certainly be a problem for the teeth. Licorice root is better, but it does need to be used with care. Briefly chewing a small piece of the root might be helpful, but I don't think that chewing it for a long time would be a good idea because it would give a lot of time for potentially harmful substances to be released from the root and absorbed into the body. Even chewing a small amount of the root could be dangerous because we don't know the concentration of the chemicals that we're absorbing.

Kathy Kiesow on June 28, 2017:

Why not in the mea time, chew a portion of licorice root, then swish it in the mouth for 10 minutes or longer, and maybe even help it with coconut oil for oil pulling..I had no idea about the oral benefits of licorice, and I love licorice.But rarely eat the candy because of sugar.

Linda Crampton (author) from British Columbia, Canada on February 08, 2017:

Thanks for the comment and for sharing the information, Patty. Your friend's experience is definitely something to keep in mind.

Patty Inglish MS from USA and Asgardia, the First Space Nation on February 08, 2017:

This is a very interesting article. A friend in her 30s used to drink a cup of licorice root tea a few times a week. One day, she drank a quart of licorice root iced tea and had a full anaphylactic , allergic reaction. Went to the ER and was fine, but she was surprised.

Linda Crampton (author) from British Columbia, Canada on February 08, 2017:

Tom, since you are taking a blood pressure medication, I think it's very important that you talk to your doctor and perhaps your dentist as well before drinking a tea made from licorice root or using a licorice mouthwash.

Tom on February 08, 2017:

Recently bought one pound of licorice root. Ground up two roots to use in tea. Have moderate BP and taking BP med. Don't believe it is crucial. Never had licorice candy made with real licorice. Don't plan to use it daily, however, considering making a wash to run in my water pick. Any thoughts?

Linda Crampton (author) from British Columbia, Canada on March 26, 2015:

Thank you for the comment, Roberta. Congratulations on having your own teeth! I hope your friend is helped.

roberta on March 26, 2015:

as one who has her own teeth at 77 i am inquiring for a person who has a qite severe problems with teeth and gums has no dental insurance per haps this ariticle can help prevent more damage with her doctors permission very well written

Linda Crampton (author) from British Columbia, Canada on April 21, 2014:

Thank you very much for sharing your experience, Quila!

Quila on April 21, 2014:

I love liquorice root and have been chewing it on and off for as long as I can remember. I don't know much about the chemicals it contains, but the stringy texture (once chewed) seems to make a great tasting toothbrush. Of course, it's also a pretty good laxative - whether you need one or not - so, whilst I've no idea how much is safe, I would definitely say no more than one stick a day ;-)

Linda Crampton (author) from British Columbia, Canada on December 30, 2013:

Hi, anar. I've never seen any scientific reports about licorice root being an effective smoking cessation aid. It sounds risky to me because of the high chance of ingesting too much licorice. As you say, the danger of eating or sucking licorice root varies, depending on the size of the root, its chemical content and the frequency of use. There's a big chance of developing problems if multiple sticks are used each day, though, or even if one stick is used if it's big enough. Your doctor would probably be the best person to consult. I wish you luck in your quest to stop smoking.

anar on December 30, 2013:

Have you come across any data about how much licorice is ingested by chewing on the root itself and swallowing the juices? Licorice root is often recommended as a smoking cessation aid, but it's not very clear how many sticks are considered safe to consume in a day, week etc. Obviously it must vary incredibly, but I wish I could find a ballpark rule of thumb to follow.

Linda Crampton (author) from British Columbia, Canada on September 17, 2012:

Thanks for the comment, Doodlehead. It is nice to know that licorice has some health benefits!

Doodlehead from Northern California on September 17, 2012:

Love that stuff. So nice to know it is healthy. Interesting about the gum disease bacteria.

Linda Crampton (author) from British Columbia, Canada on January 25, 2012:

I agree, Peggy - more research does need to be done. The potential benefits look very helpful, though! I would certainly use licorice toothpaste and mouthwash if they were shown to improve oral health. Thank you for the votes.

Peggy Woods from Houston, Texas on January 25, 2012:

How very interesting! I used to love those licorice strands of candy when I was a kid but even back then seldom ate much candy. I had no idea of the possible healthful and well as harmful effects of using licorice. It would seem that more research needs to be done. I like the idea of licorice mouthwash or toothpaste...especially if it would cut down on harmful bacteria in the mouth. Go researchers!!! Up, useful and interesting votes!

Linda Crampton (author) from British Columbia, Canada on January 15, 2012:

Thanks, Prasetio. I appreciate your comment and rating!

prasetio30 from malang-indonesia on January 15, 2012:

Again, you make this hub very detail and I learn many things from you. Thanks for writing and share with us. Rate up!


Linda Crampton (author) from British Columbia, Canada on January 14, 2012:

Hi, Nell. Thanks for commenting. Yes, licorice does need to be taken in moderation, but it does seem to have some benefits, and it's certainly tasty!

Nell Rose from England on January 14, 2012:

Hi, I remember reading years ago that it was good for asthmatics, but there was a down side there too, great stuff if taken in moderation, but as you say you have to be careful, thanks for the info, great stuff! cheers nell

Linda Crampton (author) from British Columbia, Canada on January 14, 2012:

Thank you very much for the comment and vote, Tom. I like licorice too, which I enjoy in the form of licorice tea. It's delicious!

Thomas Silvia from Massachusetts on January 14, 2012:

Hi Alicia, great well written and researched hub on the benefits of using licorice safely . I love black licorice! I found the information was very interesting and some of it i did not know.

Awesome and vote up !!!

Linda Crampton (author) from British Columbia, Canada on January 11, 2012:

Thank you, Maren Morgan. That's a good way of describing licorice - it is tricky! It seems to offer some great health benefits, but it's important not to eat too much of it.

Maren Elizabeth Morgan from Pennsylvania on January 11, 2012:

Sounds like a tricky chemical. Great research!

Linda Crampton (author) from British Columbia, Canada on January 11, 2012:

I would love chocolate toothpaste, drbj! I hope that someone invents it!! I've used toothpaste containing licorice, but just a small amount of licorice was added to the toothpaste to improve its flavor, not to be antibacterial. Thanks for the comment.

Linda Crampton (author) from British Columbia, Canada on January 11, 2012:

Thank you very much for the kind comment, b. Malin! Licorice is certainly an interesting plant and substance. I love the taste of licorice, and its possible health benefits are intriguing.

drbj and sherry from south Florida on January 11, 2012:

I'm looking forward to seeing licorice toothpaste and chewing gum on the market, Alicia. 'Twould almost be as stupendous as finding chocolate toothpaste containing antibacterial properties. Don't laugh. Stranger things have happened.

Thanks for this edifying and interesting hub.

b. Malin on January 11, 2012:

I used to LOVE Licorice as a child and now to hear how Beneficial it can be, may get me to once again eat it as an Adult! Just imagine Licorice Toothpaste! Wonderful, useful, Hub Alicia, once again, a most Enjoyable and Enlightening read.

Linda Crampton (author) from British Columbia, Canada on January 11, 2012:

Hi, Eddy. Thanks for the comment. I hope that you have a good day too!

Eiddwen from Wales on January 11, 2012:

A very well informed and useful hub.

Thank you for sharing;

Take care and enjoy the rest of your day;


Linda Crampton (author) from British Columbia, Canada on January 11, 2012:

Thank you, CMHypno. I agree, it is very important to look at the side effects of any herbal remedy, and of other medications too.

CMHypno from Other Side of the Sun on January 11, 2012:

Interesting article on licorice Alicia, especially as you look at the possible downsides of using licorice as well as the benefit. I think with all natural and herbal remedies it is important for people to investigate any potential side effects as well as the benefits