What Is DGL Licorice? Uses, Benefits, and Safety

DGL licorice is a specially processed form of licorice root (Glycyrrhiza glabra) from which glycyrrhizin, the compound responsible for most of licorice’s well-known side effects, has been removed. The abbreviation stands for “deglycyrrhizinated licorice.” It was developed to preserve the soothing and anti-inflammatory properties that traditional herbalists valued in licorice while eliminating the compound that can raise blood pressure and disrupt hormone balance. DGL is sold as chewable tablets, capsules, powders, and mouthwashes, and it is most commonly marketed for digestive complaints and mouth sores.

Why Glycyrrhizin Gets Removed

Glycyrrhizin is the naturally occurring sweetener in licorice root, and it is also the reason whole licorice can be dangerous in anything beyond small amounts. It blocks an enzyme in the kidneys that normally inactivates cortisol, which causes the body to retain sodium and water while losing potassium. The downstream effect mimics a condition called pseudoaldosteronism: blood pressure climbs, potassium drops, and hormone levels shift. A randomized crossover trial found that even a low daily dose of licorice raised systolic blood pressure by about 3 mm Hg on average and suppressed renin by roughly 30% and aldosterone by about 45% compared to a control period.¹ Those hormonal shifts are not trivial. In people who already have high blood pressure, heart disease, or kidney problems, even modest chronic licorice intake can be medically significant.

By stripping out the glycyrrhizin, DGL sidesteps this entire cascade. The remaining extract retains hundreds of other bioactive compounds, including flavonoids like liquiritigenin and isoliquiritigenin, which are thought to carry anti-inflammatory and mucosal-protective effects. The trade-off is straightforward: DGL is far less likely to raise blood pressure or deplete potassium, but it also lacks whatever therapeutic benefit glycyrrhizin itself might have offered.

DGL and Stomach Ulcers

The original rationale for DGL centered on peptic ulcer disease. In the mid-twentieth century, researchers observed that licorice seemed to help stomach ulcers heal, and DGL became a way to deliver that benefit without the cardiovascular risks. Several early trials, particularly from the 1960s and 1970s, tested DGL tablets against placebos or standard ulcer drugs. The results were uneven. A double-blind trial of the DGL-based product Caved-S in patients with gastric ulcers found no tendency toward quicker healing compared to placebo, concluding that the study was unable to demonstrate any healing effect.²

A more recent systematic review and meta-analysis pooled available studies on licorice for peptic ulcer disease overall. While some individual studies did report positive effects on ulcer healing, others did not. When the data were combined, the pooled results for both symptom improvement in pain and complete ulcer healing were not statistically significant.³ That does not necessarily mean licorice or DGL has zero effect on the stomach lining, but it does mean the current body of clinical evidence is too inconsistent to declare DGL a reliable ulcer treatment. Given that modern medicine now has highly effective drugs for ulcers and the bacterium that causes most of them, DGL is not a substitute for standard care if you have a confirmed peptic ulcer.

Mouth Ulcers and Canker Sores

Where DGL has shown more consistently positive results is in aphthous stomatitis, the medical term for recurrent canker sores. These painful mouth ulcers affect a large portion of the population and tend to recur unpredictably. Topical licorice, including DGL formulations, has been tested as a mouthwash or topical paste in several small trials.

In one early study of 20 patients using a DGL mouthwash, 15 experienced 50 to 75 percent improvement within one day, and their ulcers fully healed by the third day.⁴ A broader systematic review of clinical trials on topical licorice for canker sores found that all included studies showed significant effects on reducing ulcer size, with similar results for pain relief.⁵ A double-blind randomized trial testing a licorice-containing solution against a control found that the licorice group had significantly lower average pain scores at days one, three, and five, and the solution reduced the average wound healing time by about a day and a half compared to the control, with no adverse effects observed.⁶

These are small studies, and canker sores tend to heal on their own within one to two weeks regardless. Still, the consistency of the direction across trials, along with the lack of observed side effects from topical use, has made DGL mouthwash one of the more credible over-the-counter options for people who get frequent canker sores and want something to speed up healing or reduce pain. Dissolving a DGL tablet in warm water to create a mouthwash is a common homemade approach, though commercial DGL oral products also exist.

Digestive Complaints Beyond Ulcers

Many people reach for DGL not because they have a diagnosed ulcer but because they deal with acid reflux, heartburn, or a general sense of stomach discomfort after eating. The theory is that licorice compounds stimulate mucus production in the stomach lining, creating a more protective barrier against acid. This is plausible on a basic physiological level, and integrative medicine practitioners often include licorice-derived botanicals as part of a broader approach to managing reflux and functional dyspepsia in both adults and children.⁷

The honest picture here is that rigorous clinical trials specifically testing DGL for acid reflux or functional dyspepsia in adults are scarce. Much of the popularity of DGL for these complaints comes from anecdotal reports and its long history in traditional use rather than from randomized controlled trials showing it outperforms a placebo. That does not make it useless. Many people report subjective relief, and given DGL’s mild safety profile, trying it for occasional heartburn or stomach discomfort carries little risk. But if you have persistent reflux symptoms, relying on DGL instead of seeing a doctor could mean missing a condition that needs proper diagnosis.

Anti-Inflammatory and Antimicrobial Properties

Laboratory and animal research has identified several mechanisms by which licorice compounds, including those retained in DGL, could dampen inflammation and fight certain microbes. One area of interest involves Helicobacter pylori, the bacterium responsible for most stomach ulcers. An in vitro study found that licorice extract inhibited the growth of H. pylori in a dose-dependent manner, and when combined with a probiotic and perilla extract, it effectively prevented the bacteria from attaching to stomach lining cells.⁸ This is promising in a petri dish, but “inhibits bacteria in a lab” is a long way from “cures an active infection in a human stomach.” Standard H. pylori treatment uses a combination of antibiotics, and licorice is not part of that protocol.

On the inflammation front, an animal study found that licorice flavonoid extract reduced disease markers in a model of ulcerative colitis. The treatment suppressed pro-inflammatory signaling pathways, reduced colon damage, and restored beneficial gut bacterial populations.⁹ Again, animal studies identify possible mechanisms but do not prove that swallowing a DGL tablet would produce the same effect in a person with inflammatory bowel disease. Researchers are interested in licorice flavonoids for gut inflammation, but the clinical trials that would confirm whether DGL helps people with conditions like ulcerative colitis have not been done yet.

What Active Compounds Stay in DGL

Removing glycyrrhizin does not leave an inert powder. Licorice root contains over 300 identified compounds, and many of the flavonoids remain in DGL preparations. Two that have received the most research attention are isoliquiritigenin and liquiritigenin. These flavonoids are absorbed into the bloodstream after oral intake, though their bioavailability is moderate. In animal pharmacokinetic studies, isoliquiritigenin showed oral bioavailability in the range of roughly 23 to 34 percent depending on dose, with the liver, heart, and kidney serving as major distribution tissues.¹⁰

An interesting finding from pharmacokinetic work is that some licorice flavonoids undergo biotransformation in the gut. After oral administration of a licorice root extract in rats, plasma levels of isoliquiritigenin and liquiritigenin initially dropped and then rose again at four to ten hours, because gut bacteria and intestinal enzymes were converting another licorice compound, liquiritin, into those two active flavonoids.¹¹ This suggests that DGL’s effects may partly depend on your individual gut microbiome and its ability to convert precursor compounds into their active forms, which could help explain why people report variable results with the same product.

Safety Profile and Who Should Be Cautious

DGL is generally regarded as safe for most adults at typical supplement doses, and this is the whole point of its existence. By removing the glycyrrhizin, you remove the main driver of blood pressure elevation, potassium loss, and hormonal disruption. None of the clinical trials on DGL for mouth ulcers reported adverse effects, and integrative practitioners often recommend it precisely because it is well tolerated.

That said, “safer than whole licorice” is not the same as “safe for everyone.” Whole licorice root possesses significant estrogenic activity, and some evidence suggests it may increase the risk of premature birth. Because DGL still contains many of the same flavonoids found in whole licorice, and because the completeness of glycyrrhizin removal can vary between products, pregnant and nursing women are generally advised to avoid it. The same caution applies to women with a history of breast cancer, given licorice’s estrogenic properties. Maximum safe doses for young children and for people with severe liver or kidney disease have not been established.¹²

If you take blood pressure medications, diuretics, corticosteroids, or blood thinners, mention DGL to your doctor before adding it. Although the glycyrrhizin is largely removed, “deglycyrrhizinated” is a processing claim, not a guarantee of zero glycyrrhizin, and some residual amount may remain. For a healthy adult using DGL occasionally for heartburn or canker sores, that residual amount is unlikely to matter. For someone on multiple medications with existing cardiovascular risk, even a small amount might not be worth the gamble.

Chewable Tablets vs. Capsules

DGL supplements come in several forms, and the choice matters more than you might expect. For digestive complaints, many practitioners specifically recommend chewable tablets rather than capsules. The reasoning is that chewing mixes the DGL with saliva and allows it to coat the esophagus and stomach lining on the way down, which may enhance its mucus-stimulating effect locally. Swallowing a capsule bypasses the mouth and esophagus entirely and delivers the extract further along the digestive tract, which could reduce its contact time with the upper GI lining where symptoms like heartburn and gastritis originate.

For canker sores, the delivery method is even more specific. You want direct contact with the sore, so dissolving a DGL tablet in a small amount of warm water and using it as a mouthwash, swishing for a few minutes, is the approach that aligns with the trials showing benefit. Simply swallowing a tablet would do nothing for a mouth ulcer. Some products are formulated as lozenges designed to dissolve slowly in the mouth, which serves the same purpose.

Dosing varies by product, but most chewable DGL tablets contain 380 to 400 milligrams of deglycyrrhizinated licorice extract per tablet, and typical recommendations suggest one to two tablets chewed before meals for digestive support. There is no universally agreed-upon clinical dose, because the supplement has never gone through the kind of large-scale dose-finding trials that pharmaceutical drugs undergo.

Common Misconceptions About DGL

One widespread belief is that DGL “heals the gut lining.” You will find this phrase repeated across supplement marketing and wellness blogs. The evidence for this is weaker than the confident phrasing suggests. The older ulcer trials, which are the studies that most directly tested whether DGL heals damaged tissue, produced mixed to negative results. What the more positive evidence supports is that DGL may reduce pain from mouth sores and possibly provide symptomatic relief from stomach discomfort. That is a meaningful benefit for everyday quality of life, but it is not the same as healing damaged tissue.

Another common confusion is treating DGL and whole licorice root as interchangeable. They are not. Supplements labeled “licorice root” or “licorice extract” without the “deglycyrrhizinated” designation contain glycyrrhizin and carry the blood pressure and potassium risks. Some combination herbal products include licorice root as one of several ingredients without specifying whether it is deglycyrrhizinated. If avoiding glycyrrhizin matters to you, read labels carefully and look specifically for “DGL” or “deglycyrrhizinated.”

A third misconception is that because DGL is natural and sold over the counter, it cannot interact with medications. Licorice flavonoids can influence drug-metabolizing enzymes in the liver, which means they have the theoretical potential to alter how quickly your body processes certain medications. The clinical significance of these interactions at typical DGL doses has not been well studied, but the possibility is real enough that anyone on prescription medications should treat DGL like any other supplement and mention it to their pharmacist or doctor.

Where the Research Stands

DGL occupies a curious middle ground in evidence-based medicine. It has been around for decades, and its safety advantage over whole licorice is well established. But the clinical evidence for its therapeutic benefits remains thin by modern standards. The strongest signal comes from topical use for canker sores, where multiple small trials consistently show faster healing and reduced pain. For stomach-related complaints, the evidence is more about biological plausibility and traditional use than about strong clinical trial results. The animal and lab research on licorice flavonoids is genuinely interesting, pointing toward anti-inflammatory and antimicrobial properties, but translating those findings into proven human therapies requires clinical trials that largely have not happened yet.

Part of the reason is economic. DGL is an unpatentable natural extract, which means no pharmaceutical company has a financial incentive to fund the large, expensive trials that would definitively answer whether it works and for whom. The research that does exist tends to be small, older, and methodologically limited. This is not unique to DGL; it is a familiar story across the entire botanical supplement space. For the consumer, the practical implication is that DGL is best viewed as a low-risk option worth trying for mild, self-limiting complaints like occasional heartburn or canker sores, but not as a treatment for serious digestive diseases.