Licorice root is a plant root used in foods, teas, mouth products, skin products, and supplements. Human studies suggest possible benefits in a few specific settings, especially mouth sores and sore throat after intubation, but the National Center for Complementary and Integrative Health says there is not enough high-quality evidence to clearly support it for any health condition.
The form matters. Licorice can contain glycyrrhizin, a compound linked with serious side effects when intake is high or long-term, including high blood pressure and irregular heartbeat.
Quick facts: forms, doses studied, and uses
| Form studied | Dose or concentration reported | Study length | Main use studied |
|---|---|---|---|
| Topical licorice extract | 1% or 5% in paste, patch, or mouthwash | Healing reported within 4 to 8 days in reviewed trials | Recurrent canker sores |
| Licorice gargle or lozenge | Amount was not stated in the review abstracts | Used before surgery | Sore throat after breathing-tube placement |
| Licorice preparations, including glycyrrhizic acid compounds | Preparations varied between trials | Durations varied between trials | Liver enzyme changes in people with primary liver disease |
| Oral products without glycyrrhizin, often called DGL | No research dose stated on the official page | Up to 4 months | Safety information, not a proven use |
These are research details, not suggested doses. A study result also depends on the outcome measured, not just the ingredient; surrogate outcomes in trials explains why a change in a lab number may not answer every practical question.
What do human studies show?
Recurrent canker sores
This is one of the more focused areas of research. A 2023 systematic review of clinical trials included six studies with 314 people who had recurrent canker sores. The trials used licorice as a paste, patch, or mouthwash at 1% or 5%. The review reported reductions in pain, ulcer size, and healing time, with healing reported over 4 to 8 days. The studies used different forms and methods, so the results do not identify one best product or routine.
NCCIH likewise reports that a licorice mouth rinse or gargle might reduce ulcer size and pain, while topical licorice might reduce ulcer size only. One study combined licorice extract with a medicine, so that result cannot tell you what licorice alone would do.
Sore throat after intubation
Licorice gargles or lozenges used before surgery might prevent or lessen sore throat after intubation, according to NCCIH. This is a narrow, short-term surgical setting. It does not show that tea, candy, or an oral supplement has the same effect for an everyday sore throat.
Liver enzyme results in people with liver disease
A 2024 systematic review and meta-analysis combined 15 randomized controlled trials involving 1,367 people with primary liver disease. Compared with control groups, licorice preparations were linked with lower ALT by 15.63 U/L and AST by 7.37 U/L. ALT and AST are blood-test markers that can rise when the liver is under stress.
The preparations, locations, and study lengths differed widely. Gamma-glutamyl transferase and total bilirubin did not change significantly overall. This is an effect on lab markers, not proof of a patient benefit, which is why the difference between lab outcomes and patient outcomes matters.
Skin use and burn healing
For skin, the evidence is early. NCCIH says preliminary evidence suggests topical gels containing licorice root might help eczema symptoms or burn healing, but more research is needed to confirm effects and safety. In a double-blind randomized trial, 50 people with second-degree burns used a hydroalcoholic licorice-root hydrogel or a hydrogel without the extract for 15 days. The licorice group had lower redness, inflammation, pain, and burning at some measured time points, and faster healing than the control group.
That one study used a specific hydrogel for burns. It does not show that every skincare product containing licorice root will give the same result.
Other uses people ask about
Licorice is promoted for digestive, respiratory, and energy support, but NCCIH says it is unclear whether licorice-only products affect digestive symptoms. The agency also says there is no good evidence supporting licorice for COVID-19. A review of four randomized trials of a licorice-and-jujube formula found that it may improve sleep symptoms during menopause, but concluded that evidence was insufficient for clinical recommendations; that finding concerns a combination formula, not licorice root alone.
What doses have researchers used?
Researchers used different species, extracts, preparations, and routes of use. That makes a single daily amount impossible to pull from these studies. For recurrent canker sores, the 2023 review described 1% and 5% topical preparations. For liver studies, the 2024 meta-analysis reported that the preparations and durations varied widely. NCCIH states that oral products without glycyrrhizin may be safe for up to four months, but it does not provide a daily research dose.
When comparing ingredient studies, check the exact form, dose, and condition rather than assuming that one result applies to every extract. study details by form and dose shows why those distinctions matter.
Can licorice root raise blood pressure or cause side effects?
Yes. NCCIH says glycyrrhizin, also called glycyrrhizic acid, can cause serious adverse effects such as irregular heartbeat and cardiac arrest, especially with large amounts or long-term use. Even small amounts from licorice-root products have been linked with severe adverse effects in people who consume a lot of salt and in people with high blood pressure or heart or kidney conditions.
| Question | What the official information says |
|---|---|
| High blood pressure | Glycyrrhizin-containing licorice can contribute to serious effects; people with hypertension may be especially sensitive. |
| Heart rhythm | Irregular heartbeat and cardiac arrest have been reported with high or long-term intake. |
| Skin irritation | Topical licorice may cause skin irritation in some people. |
| Medicines | Interactions with corticosteroids have been reported. NCCIH also advises discussing licorice with a health care provider before using it with any medicine. |
The official page does not provide a clear answer on whether licorice causes diarrhea, headaches, or anxiety. If a symptom occurs after using a product, the ingredient list and form are useful details to bring to a clinician or pharmacist.
Why avoid licorice root during pregnancy or breastfeeding?
NCCIH says consuming large amounts of oral licorice extract, about 250 grams of licorice per week, during pregnancy is unsafe and can increase the risk of delivery before 38 weeks of pregnancy. It also says little is known about safety during breastfeeding.
For skincare, NCCIH says topical licorice may be safe in the short term but can irritate skin in some people. The page does not give a pregnancy-specific conclusion for topical licorice. If you are pregnant, breastfeeding, or considering a product that combines oral and topical ingredients, ask a clinician about that exact product and its full label.
Who should talk to a clinician first?
Talk to a clinician or pharmacist before using licorice root if you are pregnant, breastfeeding, have high blood pressure, a heart condition, or kidney disease, consume a high-salt diet, or take any medicine. This is particularly important if you take corticosteroids because interactions have been reported. Do not use an ingredient page as a reason to start, stop, or change prescribed medicine.
What is still unknown?
Important gaps remain. There is no single established daily amount for licorice root because products and studies vary so much. High-quality evidence does not clearly support licorice for any health condition, according to NCCIH. The long-term safety of many oral products, the safety of licorice during breastfeeding, and whether topical skin products are safe during pregnancy all need clearer research.
Licorice is also called “sweet root,” and it is used as a flavoring in foods, candy, and tobacco products. Many U.S. products labeled “licorice” use anise oil instead of actual licorice, according to NCCIH, so the label matters.
How to read a label that lists licorice root
- Look for the form. A root powder, extract, topical gel, mouthwash, and glycyrrhizin-free product are not interchangeable.
- Check whether glycyrrhizin is named. This is the compound connected with the blood-pressure and heart-rhythm concerns described by NCCIH.
- Find the amount per serving. A label that lists licorice inside a proprietary blend may not tell you how much of the ingredient is present.
- Check the full ingredient list. Research on a combination formula or a blend cannot be treated as research on licorice root alone.
- Match the label to the question. A topical study does not answer an oral-supplement question, and a mouthwash study does not establish a benefit from tea.
Before you order or use a licorice product: confirm the exact form, whether it contains glycyrrhizin, the amount per serving, all other ingredients, and whether it fits with your medicines or health conditions.
By ClinicalStudyConnect.com Research Desk
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.