Licorice Root for Tooth Decay, Gum Disease and Oral Health

Licorice root is edible, sweet and delicious.
Licorice root is edible, sweet and delicious. | Source

The Licorice Plant

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

Licorice has been a popular food additive since ancient times. It's also had a long use in traditional medicine. Today licorice is claimed to have many health benefits. There is preliminary evidence supporting some of these claims, but for other claims the evidence is mixed. Research suggests that licorice may be very beneficial for oral health, however. It inhibits the activity of bacteria that cause tooth decay and gum disease.

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

Leaves of a licorice plant (Glycyrrhiza glabra)
Leaves of a licorice plant (Glycyrrhiza glabra) | Source

Two Antibacterial Compounds in Licorice Root

Two antibacterial chemicals in licorice root are licoricidin and licorisoflavan A. In 2012, an international research team made some interesting discoveries that linked these chemicals to oral health. The results were published by the American Chemical Society.

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 licorice chemicals 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 licorice needs to be used and how long it will have to stay in contact with oral bacteria to inhibit their growth.

Streptococcus mutans, a common cause of tooth decay
Streptococcus mutans, a common cause of tooth decay | Source

Trans-Chalcone and Oral Bacteria

In 2015, 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 the natural substance in licorice 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, licorice compounds were continually added to the mouth.

Flowers of a licorice plant
Flowers of a licorice plant | Source

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 licorice lollipops, the licorice extract in the lollipops 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 lollipop 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. It could be a very useful substance for improving oral health.

The Licorice Plant - Glycyrrhiza glabra

Potential Dangers of Licorice Root Products

Black and red licorice candy rarely contain real licorice extract. 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. In some cases licorice use can raise blood pressure and lower the potassium level in the blood, leading to fluid and salt retention and possible heart problems. In addition, it may cause muscle weakness.

Licorice contains isoflavones, which are phytoestrogens, so it may affect the function of hormones in the body. Some evidence suggests that it lowers the testosterone level in men. Another potential problem with ingesting licorice is that it may interfere with the action of certain medications.

The amount of licorice root that can be safely tolerated depends on body weight as well as pre-existing health conditions and life stage. Pregnant and nursing women and people with estrogen-sensitive diseases shouldn’t eat licorice.

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

Harmful Effects of High Doses

The consensus of health experts seems to be that for most people licorice root is safe when used occasionally to flavor foods or drinks, provided small amounts are used. It may be safe in some people when used in larger amounts as a medicinal supplement, but mustn’t be used in medicinal doses for longer than four weeks. Ingesting very large amounts of licorice root or using licorice as a supplement for longer than four weeks may be dangerous.

The maximum dose of licorice that is safe is unknown. 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, as the video below shows.

The University of Maryland Medical Center states that eating more than 20 grams of licorice a day on a regular basis can be dangerous. Licorice raises the blood level of a hormone called aldosterone. 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.

The medical center also says that even 5 grams of licorice per day may be harmful for people who already have heart disease or kidney problems. It seems advisable to ingest considerably less than this amount when using licorice for oral health.

Seizures from Eating an Excessive Amount of Licorice

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 licorice consumption. The boy described in the video above had eaten twenty licorice candies a day for four months before his seizures. 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 of licorice or if DGL has all the health benefits that are attributed to whole licorice.

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 bad effects are still possible in sensitive people. Licorice is assumed to contain 0.2% glycyrrhizic acid by weight.

A Licorice Poll

Do you eat licorice?

  • I eat licorice root.
  • I eat candy made of real licorice.
  • I eat both licorice root and candy made of real licorice.
  • I eat licorice candy, but it doesn't contain real licorice.
  • I never eat licorice. I don't like it.
See results without voting
A licorice plant
A licorice plant | Source

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. There are already oral hygiene products available that are flavored with licorice root or licorice root extract, but it’s unknown if they contain enough licorice to affect oral bacteria.

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 antibacterial licorice chemicals. Until then, we need to be careful when we eat licorice products or drink licorice tea. It would be a good idea to keep track of the amount of licorice that we’re ingesting in order to prevent any health problems from the substance.


Dried licorice root fights oral bacteria - from the American Chemical Society

Licorice lollipops and oral health - from the European Archives of Paediatric Dentistry

Trans-chalcone and oral bacteria - from the University of Edinburgh

Black licorice dangers - from the FDA (Food and Drug Administration)

Licorice uses, precautions and interactions - University of Maryland Medical Center

Excess licorice and seizures from ScienceDaily

Safe level of glycyrrhizic acid - from WHO

© 2012 Linda Crampton

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Comments 26 comments

CMHypno profile image

CMHypno 4 years ago from Other Side of the Sun

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

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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

Eiddwen profile image

Eiddwen 4 years ago from Wales

A very well informed and useful hub.

Thank you for sharing;

Take care and enjoy the rest of your day;


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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

b. Malin profile image

b. Malin 4 years ago

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.

drbj profile image

drbj 4 years ago from south Florida

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.

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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.

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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.

Maren Morgan M-T profile image

Maren Morgan M-T 4 years ago from Pennsylvania

Sounds like a tricky chemical. Great research!

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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.

kashmir56 profile image

kashmir56 4 years ago from Massachusetts

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 !!!

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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!

Nell Rose profile image

Nell Rose 4 years ago from England

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

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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!

prasetio30 profile image

prasetio30 4 years ago from malang-indonesia

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


AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

Thanks, Prasetio. I appreciate your comment and rating!

Peggy W profile image

Peggy W 4 years ago from Houston, Texas

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!

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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.

Doodlehead profile image

Doodlehead 4 years ago from Northern California

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

AliciaC profile image

AliciaC 4 years ago from British Columbia, Canada Author

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

anar 2 years ago

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.

AliciaC profile image

AliciaC 2 years ago from British Columbia, Canada Author

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.

Quila 2 years ago

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 ;-)

AliciaC profile image

AliciaC 2 years ago from British Columbia, Canada Author

Thank you very much for sharing your experience, Quila!

roberta 19 months ago

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

AliciaC profile image

AliciaC 19 months ago from British Columbia, Canada Author

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

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    Linda Crampton (AliciaC)1,242 Followers
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    Linda Crampton has an honours degree in biology. She is very interested in the production of medicines from chemicals in nature.

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