Licorice root (Glycyrrhiza glabra)
Summary
The main safety issue comes first: glycyrrhizin in licorice raised blood pressure even at 100 mg/day in a 2024 trial, and heavy use has caused severe low potassium and a hypertensive crisis. One 50-person trial of a low-glycyrrhizin extract, co-authored and randomised by the extract's developer, improved indigestion symptoms (grade D). High intake in pregnancy was linked to poorer outcomes in children.
Key facts
- 100 mg/day glycyrrhizic acid for 2 weeks raised home systolic BP 3.1 mmHg and suppressed renin and aldosterone (n = 28)[2]
- Systolic BP rose 3.1–14.4 mmHg with 50–200 g licorice/day (75–540 mg glycyrrhetinic acid)[3]
- Case: potassium 2.2 mmol/L, BP 239/114 and pulmonary oedema needing intensive care after heavy licorice intake[5]
- Maternal glycyrrhizin ≥500 mg/week was linked to 7-point lower child IQ scores (n = 378)[4]
- A glycyrrhizin-poor extract (GutGard, ≤0.5% glycyrrhizin) improved functional dyspepsia scores vs placebo (n = 50)[1]
- 3 graded human outcomes on this page
- October 13, 2026
How it works
EstablishedGlycyrrhizin and its metabolite glycyrrhetinic acid inhibit 11-beta-hydroxysteroid dehydrogenase type 2, letting cortisol activate mineralocorticoid receptors; this causes sodium retention, potassium loss and higher blood pressure (pseudo-aldosteronism).[2][5]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Pregnancy | Grade C | Worsened | Observational · n = 378 · 2017 | 1 row |
| Blood pressure | Grade C | Worsened | Crossover RCT · n = 28 · 2024 | 1 row |
| Digestion | Grade D | Improved | RCT · n = 50 · 2012 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Child cognition, behaviour and puberty after licorice in pregnancy | Worsened | Grade C | Observational · n = 378 · 2017 Children (mean age 12.5) born in Helsinki in 1998 and their mothers Form: Maternal licorice intake · Dose: ≥500 mg glycyrrhizin/week vs less · Duration: Pregnancy (exposure) High exposure: IQ about 7 points lower, poorer memory, 3.3-fold higher odds of ADHD problems, and earlier puberty in girls. | 28158597 (opens PubMed)Source [4] |
| Home blood pressure, renin and aldosterone | Worsened | Grade C | Crossover RCT · n = 28 · 2024 Healthy young adults (median age 24) Form: Licorice vs control product · Dose: 100 mg glycyrrhizic acid/day · Duration: 2 weeks per period Home systolic BP +3.1 mmHg vs control (P = 0.018); renin −30% and aldosterone −45%; NT-proBNP rose in the most sensitive quartile. | 38246526 (opens PubMed)Source [2] |
| Functional dyspepsia symptoms | Improved | Grade D | RCT · n = 50 · 2012 Adults with functional dyspepsia (Rome III; India) Form: GutGard licorice flavonoid extract (glycyrrhizin ≤0.5%) · Dose: 75 mg twice daily · Duration: 30 days Total symptom scores and Nepean Dyspepsia Index improved more than placebo at days 15 and 30 (P ≤ 0.05); well tolerated. | 21747893 (opens PubMed)Source [1] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Licorice root and glycyrrhizin-containing extracts | Varies[2] | Glycyrrhizin is converted to glycyrrhetinic acid, the active mineralocorticoid-like metabolite.[2] | Raises blood pressure and lowers potassium in a dose-dependent way.[2][3] | Blood pressure studies |
| DGL and low-glycyrrhizin extracts (for example GutGard) | Varies[1] | GutGard is specified at ≤0.5% glycyrrhizin and ≥10% flavonoids.[1] | Well tolerated over 30 days in one trial.[1] | Functional dyspepsia |
Studied doses
Doses studied in human trials ranged from 75 mg twice daily of a low-glycyrrhizin extract for 30 days (dyspepsia) to licorice providing 100 mg glycyrrhizic acid daily for 2 weeks (blood pressure study).[1][2]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- CorticosteroidsNIH fact sheetNCCIH reports interactions between licorice and corticosteroids; glycyrrhizin amplifies cortisol-like effects.[6]
- Blood pressure medicinesRCTGlycyrrhizin raised blood pressure and suppressed renin and aldosterone in a trial, so it may work against antihypertensive treatment.[2]
- Potassium-lowering diureticsCase reportLicorice itself causes potassium loss (a published case reached 2.2 mmol/L despite replacement); potassium-wasting diuretics may add to it.[5]
- DigoxinCase reportA published case describes digitalis toxicity with heart failure in an elderly man on digoxin who was taking a licorice-containing herbal laxative; licorice can also cause severe potassium loss.[7][5]
Who should be careful
- Pregnancy
- NCCIH: large amounts (about 250 g licorice per week) in pregnancy are unsafe and linked to earlier delivery; a cohort linked high intake to poorer child outcomes.[4][6]
- High blood pressure, heart or kidney disease
- Glycyrrhizin raises blood pressure at doses as low as 100 mg/day and can cause cardiac arrest in heavy or long-term use.[2][6]
- Low potassium, on diuretics or on digoxin
- Licorice-induced potassium loss can be severe and hard to correct, and a published case linked licorice to digitalis toxicity.[5][7]
- People on corticosteroids
- Interactions with corticosteroids have been reported.[6]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Pseudo-aldosteronism
- Case report
- A 79-year-old woman eating licorice developed severe refractory hypokalaemia, a hypertensive crisis (239/114 mmHg) and pulmonary oedema requiring intensive care.[5]
- NCCIH
- Glycyrrhizin can cause serious adverse effects, such as irregular heartbeat and cardiac arrest, especially in large amounts or long-term use.[6]
Frequently asked questions
Is licorice root safe?
As a food flavour it is generally considered safe, but glycyrrhizin can raise blood pressure and lower potassium, and heavy use has caused cardiac arrest.[2][6]
What is DGL licorice?
Deglycyrrhizinated licorice has most glycyrrhizin removed; the dyspepsia trial used an extract with ≤0.5% glycyrrhizin.[1]
Does licorice help indigestion?
One 50-person trial of a low-glycyrrhizin extract found better dyspepsia scores than placebo; the extract's developer co-authored the paper and generated the randomisation list.[1]
Sources
- [1]An Extract of Glycyrrhiza glabra (GutGard) Alleviates Symptoms of Functional Dyspepsia: A Randomized, Double-Blind, Placebo-Controlled Study.. Evid Based Complement Alternat Med, 2012. RCT
- [2]A low dose of daily licorice intake affects renin, aldosterone, and home blood pressure in a randomized crossover trial.. Am J Clin Nutr, 2024. crossover-RCT
- [3]Liquorice-induced rise in blood pressure: a linear dose-response relationship.. J Hum Hypertens, 2001. open-label
- [4]Maternal Licorice Consumption During Pregnancy and Pubertal, Cognitive, and Psychiatric Outcomes in Children.. Am J Epidemiol, 2017. observational
- [5]A life-threatening case of pseudo-aldosteronism secondary to excessive liquorice ingestion.. BMC Endocr Disord, 2021. observational
- [6]Licorice Root: Usefulness and Safety. NIH National Center for Complementary and Integrative Health, 2025. fact-sheet
- [7]Congestive heart failure caused by digitalis toxicity in an elderly man taking a licorice-containing chinese herbal laxative.. Cardiology, 2002. observational
What changed
- Editorial evidence re-review: summary and FAQ now describe the GutGard trial's developer involvement as verified in the full text (7 of 11 authors at Natural Remedies, company-generated randomisation) instead of calling it sponsor-run; summary no longer says heart rhythm problems for the cited case (it was a hypertensive crisis); added a sourced digoxin interaction (PMID 12566654).
- Second-pass self-review: every PMID re-checked against NCBI esummary (title, year, no retraction or expression-of-concern flag), every dose, n and duration re-read against the PubMed abstract or PMC full text, grades held conservative, and interactions limited to what a cited source supports.
- First draft. Source titles and years taken from NCBI E-utilities esummary; abstracts read for every evidence row.