More Than a Candy Flavor
Licorice root (Glycyrrhiza glabra and its close relatives) is among the most widely used herbs in the world. It appears in European throat lozenges, in a large share of traditional Chinese formulas, in Ayurvedic preparations, in herbal teas, and in the black candy that people either love or can’t stand. Its sweetness made it a natural way to make bitter formulas easier to swallow, and its slippery, coating quality earned it a reputation for soothing sore throats and upset stomachs.
It is also one of the few common herbs with a well-understood, dose-dependent, clinically significant side effect. Most herbal safety warnings are hedged with “theoretically” and “may.” Licorice’s effect on blood pressure and potassium is established physiology. That makes it a useful herb to understand properly, both for what it might offer and for what it can do when overused.
This guide is the why behind licorice: what’s in it, how the main compound works, what the evidence supports, and who should leave it on the shelf.
What’s in Licorice Root
The root contains hundreds of compounds, but two groups matter most:
- Glycyrrhizin (also called glycyrrhizic acid) is a saponin roughly 50 times sweeter than table sugar. It typically makes up a few percent of the dried root by weight, though the amount varies widely between plants and products. It’s responsible for the sweetness, for some of the proposed benefits, and for nearly all of the risk.
- Flavonoids such as glabridin and liquiritin are polyphenols studied for antioxidant and soothing properties. These remain when glycyrrhizin is removed.
That split explains why licorice is sold in two fundamentally different forms: whole licorice, which contains glycyrrhizin, and DGL, which mostly doesn’t.
How Glycyrrhizin Raises Blood Pressure
Your kidneys contain receptors that respond to the hormone aldosterone by holding on to sodium and water and excreting potassium. Cortisol, which circulates at much higher levels than aldosterone, can activate those same receptors. Normally it doesn’t get the chance, because an enzyme in kidney tissue (11-beta-hydroxysteroid dehydrogenase type 2) converts cortisol into inactive cortisone before it can bind.
After you swallow licorice, gut bacteria convert glycyrrhizin into glycyrrhetinic acid, which inhibits that protective enzyme. With the enzyme blocked, cortisol floods the receptors and the kidney behaves as though aldosterone were sky-high. The result:
- Sodium and water retention, with swelling in some people
- Rising blood pressure
- Falling potassium, which can cause muscle weakness, cramps, and, in serious cases, dangerous heart rhythm disturbances
The effect depends on dose and duration, and individual sensitivity varies considerably. Older adults, women, and people who already have high blood pressure appear to be more susceptible. Case reports of people hospitalized after weeks of heavy licorice candy or tea consumption are a staple of medical journals, and US regulators have warned that adults over 40 who eat a couple of ounces of real black licorice daily for two weeks or more can develop heart rhythm problems.
The effect usually reverses after stopping, but recovery can take a few weeks because the enzyme inhibition lingers.
DGL: Licorice with the Risky Part Removed
Deglycyrrhizinated licorice (DGL) is processed to remove most of the glycyrrhizin, leaving the flavonoids and other constituents. Because the blood pressure mechanism runs through glycyrrhizin, DGL does not appear to carry the same risk, and it’s the form most often sold for digestive comfort.
Two caveats apply. DGL is “reduced,” not always “zero,” so quality products state a maximum glycyrrhizin content (commonly under 1 to 3 percent). And removing the risky compound may also remove some of the activity, so DGL shouldn’t be assumed to do everything whole licorice does.
What the Evidence Shows
Licorice has centuries of traditional use and a thin layer of modern clinical evidence. An honest sorting:
Sore throat and cough. Licorice’s coating quality is the basis for its use in lozenges and teas, alongside other soothing herbs such as marshmallow root and slippery elm. The most rigorous data come from an unusual setting: several controlled trials found that a licorice gargle or lozenge before surgery reduced sore throat after a breathing tube was removed. Evidence for ordinary cold-related sore throats is mostly traditional, and you can compare it with similar herbs in our soothing herbs research brief.
Digestive comfort. DGL was studied decades ago for stomach lining support, with mixed results in trials that would not meet modern standards. More recently, small trials of a flavonoid-rich, low-glycyrrhizin extract (around 75 mg twice daily) reported improvements in indigestion symptoms versus placebo. These are preliminary, and licorice also appears in multi-herb digestive formulas where its individual contribution can’t be separated out.
Skin and mouth. Small studies of topical licorice gels and patches suggest modest help with canker sore discomfort and irritated skin. Topical use doesn’t raise the same systemic concerns.
“Adrenal support.” Licorice is heavily marketed for “adrenal fatigue” on the grounds that it prolongs cortisol’s activity. The mechanism is real, but it’s the same mechanism that causes the side effects, and the condition it’s sold for isn’t recognized by endocrinology. Our article on the adrenal fatigue myth covers why. Using licorice to self-manage fatigue is a poor trade.
Hormones. A few small studies reported that licorice lowered testosterone in men, while others failed to reproduce the finding. The evidence is too inconsistent to draw conclusions either way.
Dosage and How to Use It
DGL (preferred for most people):
- Chewable tablets of 380-760 mg, taken about 20 minutes before meals, up to three times daily, is the common pattern. Chewing matters in the traditional rationale, since contact with saliva is thought to be part of how it works, though this hasn’t been rigorously tested.
- Reassess after a few weeks. Ongoing digestive symptoms deserve a medical evaluation, not indefinite self-treatment.
Whole licorice root (tea, extract, capsules):
- Traditional amounts run from about 1 to 5 g of dried root per day, as tea or equivalent extract.
- Keep total glycyrrhizin under roughly 100 mg per day, the level international health bodies have suggested is unlikely to cause problems for most adults. Note that this is not a guarantee: a small controlled study in healthy young adults found that 100 mg daily for two weeks still nudged blood pressure upward.
- Limit use to 4-6 weeks, then stop.
- Because glycyrrhizin content is rarely stated on teas and varies between batches, you often can’t know your dose. That uncertainty is a good argument for choosing DGL or a product standardized with a stated glycyrrhizin content. Our guide to standardized extracts explains how to read those labels.
Remember to count all sources: herbal tea blends, lozenges, imported candy, and traditional formulas can add up without your noticing.
Who Should Avoid Licorice
Glycyrrhizin-containing licorice is not appropriate for:
- High blood pressure, even if controlled with medication
- Heart disease or heart rhythm problems
- Kidney disease
- Low potassium, or conditions that predispose to it
- Pregnancy. Observational research has linked heavy licorice intake during pregnancy with poorer outcomes, and regulators in some countries advise pregnant women to avoid large amounts. Avoid supplemental licorice while pregnant, and while nursing given the lack of data.
Drug interactions are substantial:
- Diuretics (thiazides, loop diuretics) and stimulant laxatives: additive potassium loss
- Digoxin: low potassium increases the risk of toxicity
- Blood pressure medications: licorice works against them
- Corticosteroids: licorice can prolong and amplify their effects
- Warfarin: licorice may reduce its effect
If you take any prescription medication, run licorice past a pharmacist first. Our overview of supplement-drug interactions covers the general principles.
Warning signs to stop and seek medical advice: new swelling in the ankles or face, headaches, muscle weakness or cramping, or palpitations.
How to Think About It
- Treat whole licorice like a short-course herb. It isn’t suited to daily long-term use.
- Default to DGL if your interest is digestive comfort.
- Know your candy. Much of the “licorice” sold in the US is flavored with anise oil and contains little or no real licorice, but European-style and imported black licorice often contains the real thing. Check the ingredient list for “licorice extract.”
- Sensitivity varies. Some people develop effects at intakes others tolerate, so the absence of a problem in someone else tells you little about yourself.
Bottom Line
Licorice root is a time-honored soothing herb with modest, mostly preliminary evidence for sore throat and digestive comfort. Its main compound, glycyrrhizin, has a well-documented ability to raise blood pressure and lower potassium, which makes it one of the few herbs where the dose and duration limits really matter: stay under about 100 mg of glycyrrhizin a day, keep whole-root use to a few weeks, and skip it entirely with high blood pressure, heart or kidney disease, pregnancy, or interacting medications. DGL avoids most of that risk and is the sensible choice for digestive use. Licorice doesn’t treat, cure, or prevent any disease.
This guide is educational and not medical advice. Talk to a qualified healthcare provider before starting any supplement, especially if you are pregnant, nursing, taking medication (particularly for blood pressure or the heart), or managing a health condition.