Licorice for a Sore Throat: What the Research Actually Backs Up

A humble root gargle keeps showing up in operating rooms around the world, and the studies behind it are more solid than you'd expect.

Anesthesiologists don't usually reach for herbal remedies. But at hospitals from Iran to India to the United States, some are gargling their patients with licorice water before surgery, not after. The reason is oddly specific: the breathing tube used during general anesthesia scrapes the throat, and roughly half of patients wake up with a sore throat because of it. Licorice, it turns out, has become a genuine subject of clinical study for exactly this problem.

That's a strange place to find one of the world's oldest herbal remedies. But it's also where the evidence is strongest, and it's worth understanding why.

What licorice actually is

Licorice root comes from the Glycyrrhiza glabra plant, and it contains a set of anti-inflammatory compounds that coat and calm irritated mucous membranes¹. One of the most studied of these compounds, liquiritin, has been shown in lab and animal research to dial down inflammatory signaling in lung tissue, reducing levels of inflammatory messengers like IL-6 and TNF-alpha². That's a mechanism study, done in cells and in zebrafish and mice with lung injury, not in people with sore throats. But it gives a plausible explanation for why a licorice gargle might do more than just feel soothing going down: it may actually be quieting inflammation at the site of irritation.

Traditional use lists licorice under labels like antispasmodic, alterative, and anodyne (pain-relieving), among many others catalogued in the USDA's phytochemical database³. The plant is also rich in compounds like ascorbic acid and beta-carotene, though those broader nutritional notes come from an ethnobotanical database rather than a clinical trial, so treat them as background rather than proof of anything specific.

The postoperative sore throat trials

The clearest picture comes from a 2019 systematic review and meta-analysis that pooled multiple randomized controlled trials testing topical licorice gargles or lozenges in adults undergoing general anesthesia with a breathing tube¹. Across these trials, licorice applied before surgery reduced both the incidence and the severity of sore throat afterward, compared with placebo, and the review reported it as a safe intervention in this setting.

One of the trials behind that pooled result is a 2013 double-blind study of 236 people having elective chest surgery who needed a large double-lumen breathing tube, the kind especially likely to irritate the throat⁴. Patients gargled for one minute, five minutes before anesthesia, with either a licorice solution (0.5 grams of licorice extract in water) or a sugar-water control. The licorice group had less sore throat and less coughing after the tube came out, checked at 30 minutes, 90 minutes, and again at four hours after surgery.

A second RCT looked specifically at smokers, a group whose airways are already more irritated going into surgery⁵. A hundred patients were split into two groups: one got licorice lozenges before their operation, the other got plain sugar candy. The licorice group had less coughing, less sore throat, and less hoarseness right after the breathing tube was removed. Smokers' airways tend to react more, so seeing a benefit here is a reasonably strong signal.

A third trial, from 2009, tested a licorice gargle against plain water in 40 adults undergoing lumbar spine surgery⁶. Everyone gargled for 30 seconds, five minutes before anesthesia, then researchers scored their sore throat severity on a 100-point scale at zero, two, four, and 24 hours afterward. The licorice group reported less severe throat pain both at rest and when swallowing, throughout that whole 24-hour window.

More recently, a 2022 randomized trial in Tehran compared licorice gargle against a green tea gargle and a control group in 102 people having elective surgery⁷. Patients gargled for 30 seconds after waking from anesthesia, then again two hours later, and researchers scored sore throat, cough, and hoarseness after each round. Both licorice and green tea outperformed the control, which suggests licorice's soothing effect on a freshly intubated throat isn't a one-off finding; it shows up against more than one comparison.

[COMPARE: Does a licorice gargle before surgery actually reduce sore throat afterward?] science: confirmed | Multiple randomized trials and a pooled meta-analysis found that gargling or sucking on licorice before intubation reduced both how often sore throat occurred and how bad it felt afterward, compared with water, sugar, or no treatment. | PMID:30391446, PMID:23921656, PMID:24180166, PMID:19535697 herbalism: partial | European folk practice reached for licorice root for any scratchy throat or cough, valued simply as a demulcent that coats irritated tissue, long before anyone tested it against a surgical breathing tube specifically. | [/COMPARE]

Beyond the operating room

Not every study in this area is about surgery. A small 2019 study looked at licorice mouthwash in 44 hemodialysis patients, a group that often struggles with dry mouth, thirst, and reduced saliva because of their treatment⁸. After using the licorice mouthwash, over 90 percent of the study group showed improved salivary secretion. Dry mouth and sore throat aren't the same complaint, but they share the same underlying territory: irritated, under-lubricated tissue in the throat and mouth, and this gives a hint that licorice's soothing effect isn't limited to the operating room.

The lab research on liquiritin adds a mechanistic layer to all of this. In the 2023 study using LPS-induced lung injury in cells, zebrafish, and mice, liquiritin suppressed a specific inflammatory pathway (called JNK/Nur77/c-Jun) and lowered measured levels of inflammatory proteins in lung fluid². This is animal and cell research, not a study of humans with sore throats, so it doesn't prove licorice works the same way in your throat. But it does offer a plausible reason why a plant compound might calm inflamed airway tissue, rather than just masking the sensation.

What tradition says

Ayurvedic medicine has long used licorice root as a soothing anti-tussive (cough suppressant) and expectorant, reached for when a cough won't quiet or a sore throat lingers, whether sipped as a preparation or used directly for respiratory complaints⁹.

In Traditional Chinese Medicine, a simple licorice decoction called Gan Cao Tang was the first line of response to a sore throat, trusted for the root's moistening, soothing qualities. When that wasn't enough, the classic Shang Han Lun text called for Jie Geng Tang, pairing licorice with Platycodon root for a stronger effect, cementing licorice's role as the default herb for throat trouble in Chinese medical tradition¹⁰.

Korean medicine calls licorice gamcho, and it forms the backbone of gamgil-tang, a formula brewed specifically to soothe a raw throat and calm coughing when phlegm and irritation settle into the chest¹¹.

In Kampo, Japan's herbal medicine tradition, practitioners have long reached for Kikyo-to, a simple pairing of licorice root (kanzo) with Platycodon root, specifically for the raw, scratchy throat that comes with a cold or acute upper respiratory infection¹².

Within Tibetan Sowa Rigpa medicine, licorice appears in Srolo Bzhtang, a formula recorded in the Four Medical Tantras, used as a gentle ally for chronic bronchitis and other troubled breathing¹³.

European herbalism reached for licorice root as a household remedy for scratchy throats and nagging coughs, valued as a demulcent, a substance that coats and calms irritated passages, a use so entrenched in folk practice that it's echoed in the European Medicines Agency's traditional herbal listing for cough and cold¹⁴.

Unani medicine, under the name asl-us-soos, has long used licorice root as a demulcent and expectorant for dry, rasping coughs and bronchitis, classed as a "munzij-i-balgham," a substance that ripens and eases phlegm from the throat and chest¹⁵.

Every one of these traditions, independently, landed on the same idea: licorice soothes an irritated throat. That's a striking amount of convergence across unrelated medical systems, and it lines up closely with what the modern surgical trials found, even though the traditions were treating everyday sore throats and colds, not post-anesthesia irritation specifically.

Practical takeaway

The dose used across the clinical trials was consistent and modest: about 0.5 grams of licorice extract dissolved in roughly 30 milliliters of water, gargled for 30 seconds to one minute, typically about five minutes before the throat is going to be stressed^4,6. If you're facing surgery that involves a breathing tube, this is worth raising with your anesthesia team directly, since it's a documented, low-cost intervention studied in real surgical settings, not a home remedy improvisation.

For everyday sore throats, the traditional record is broad and old, but the clinical trial evidence specifically covers the post-surgical scenario, not colds or strep. If you want to try a licorice gargle or licorice tea for a run-of-the-mill scratchy throat, the mechanism data on anti-inflammatory compounds like liquiritin at least makes it plausible², even without a trial testing that exact use case.

Safety is where you need to slow down. Licorice compounds, including glycyrrhetinic acid and glycyrrhizic acid, have documented interactions with several drug classes: antihypertensive medications (blood pressure drugs), spironolactone, hydrocortisone, and others. If you have high blood pressure, kidney issues, or take any of these medications, talk to your doctor before using licorice regularly, whether as a gargle, tea, or licorice root extract supplement. Pregnant women and anyone with heart conditions should also check first, since licorice's effect on the body's sodium and potassium balance is well documented in the safety literature. Occasional gargling with a diluted licorice solution before a medical procedure is a different matter than daily long-term use, and the two shouldn't be treated the same way.

If you're curious about other soothing options with some research behind them, slippery elm and marshmallow root share licorice's demulcent, coating quality in traditional herbalism, though this article's research brief doesn't cover clinical trial data on those specifically.

As an Amazon Associate, Holistic Codex earns from qualifying purchases. Product recommendations are editorially independent.