Licorice Root (DGL)

📜 Historical Use

Licorice is a perennial herb cultivated across Europe, Asia and the Middle East, with three main species used medicinally: Glycyrrhiza glabra, Glycyrrhiza uralensis and Glycyrrhiza inflata. It appears in the Assyrian, Egyptian, Greek, Arab, Chinese, Tibetan and Indian medical traditions — one of the few remedies shared by nearly all of them — where it was used for coughing, asthma and wound healing, and for diseases of the lungs, liver and arteries.

📊 What the Research Shows

This is where an honest reading diverges sharply from the marketing. DGL is sold overwhelmingly for heartburn, reflux and ulcers — and on digestive symptoms the National Center for Complementary and Integrative Health states plainly that it is unclear whether products containing licorice alone have an effect. The better-supported uses are ones you rarely see advertised. For canker sores, licorice mouthwash or gargle might reduce ulcer size and pain, and topical application reduced ulcer size; combining it with other treatments worked better than those treatments alone. For sore throat after intubation, gargling or using lozenges before surgery might prevent or lessen it. Preliminary evidence suggests topical gels might help eczema and burn healing, and one early study found a licorice mouthwash might improve halitosis and reduce the bacteria that cause it. For COVID-19 there is no good evidence. So the evidence for licorice is real but concentrated in the mouth and throat rather than the stomach.

DGL is usually sold as chewable tablets taken before meals. Use the deglycyrrhizinated form — products without glycyrrhizin might be safe for up to about four months, which is the boundary of what has been studied rather than a guarantee beyond it. One practical warning: many licorice products sold in the United States contain anise oil rather than genuine licorice root, so the label is not always a reliable guide to what you are taking.

This warning is about whole licorice rather than DGL, and it is the reason DGL exists: glycyrrhizin can cause irregular heartbeat and cardiac arrest, particularly in large amounts or over long periods. Even modest amounts carry risk if you have high blood pressure, a high-salt diet, or heart or kidney disease, and consistent intake has been linked to both hypertension and low potassium. Large amounts in pregnancy raise the risk of premature delivery. Interactions with corticosteroids have been reported.

⚠️ What happens if taken in excess:

For whole licorice, the concern is serious and specific: glycyrrhizin can cause irregular heartbeat and cardiac arrest, particularly in large amounts or over long periods. Even modest amounts carry risk for anyone with high blood pressure, a high-salt diet, or heart or kidney disease. Consistent licorice intake has been linked to both hypertension and hypokalaemia — low potassium — and even a low daily dose has been shown to affect renin, aldosterone and home blood pressure readings. In pregnancy, large amounts of oral licorice extract, on the order of 250 grams of licorice per week, are unsafe and raise the risk of premature delivery. Little is known about safety while breastfeeding. DGL is the exception rather than the rule here, because the glycyrrhizin has been removed: products without glycyrrhizin might be safe for up to four months. That four-month figure is the boundary of what has been studied, not a guarantee beyond it.

Interactions between licorice and corticosteroids have been reported. Beyond that specific pairing, the mechanism itself tells you where to be careful with any glycyrrhizin-containing product: because it can raise blood pressure and lower potassium, it works against antihypertensive medication and compounds the potassium loss caused by loop and thiazide diuretics — and low potassium is itself dangerous for anyone taking digoxin. If you are on any of those, the deglycyrrhizinated form is the relevant one to discuss with your prescriber, not whole licorice.

1. Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus — Cinatl J et al Lancet (2003)[PubMed ↗]