The short answer
Check with your clozapine prescriber before using licorice that contains glycyrrhizin. It can raise blood pressure and lower potassium. Low potassium matters because clozapine can affect heart rhythm. Direct evidence that this exact combination causes extra high blood pressure is lacking, so the size of any added risk is unknown.
What this answer covers
Oral Glycyrrhiza glabra root products containing glycyrrhizin. This assessment does not treat deglycyrrhizinated licorice, topical preparations, other Glycyrrhiza species or licorice-flavored products as equivalent.
- Supplement or preparation
- Glycyrrhiza glabra
- Medication ingredient
- clozapine
Why potassium matters
Licorice containing glycyrrhizin can disturb the body's salt and water balance. Blood pressure can rise and potassium can fall. Clozapine labeling identifies low potassium as a factor that increases the risk of an abnormal heart rhythm. These separate effects are a reason to review the product with your prescribing team.
What the human study shows
A small crossover study in 28 healthy adults tested licorice providing 100 mg of glycyrrhizic acid daily for two weeks. Home systolic blood pressure increased during the licorice period compared with the control period. The participants were not studied while taking clozapine, and the study does not establish a safe supplement dose for you.
Check the actual preparation
The concern is tied to glycyrrhizin-containing oral licorice. A product labeled DGL has had glycyrrhizin removed and should not be assigned the same exposure as ordinary root products. That distinction does not establish that DGL is safe with clozapine. Bring the label, serving size and ingredient list to your pharmacist or prescriber.
Monitoring and timing
Your clinician can decide whether blood pressure, potassium or other tests need checking, particularly if you already have high blood pressure, a heart condition or kidney disease. No validated number of hours between licorice and clozapine has been established to prevent these effects. Do not change your clozapine dose to compensate.
Evidence and practical considerations
Side effects & toxicity
Glycyrrhizin-containing licorice can raise blood pressure and lower potassium; clozapine-related rhythm risk makes product review relevant, although added pair-specific harm has not been measured.
- Exact scope
- Glycyrrhiza glabra root preparations containing glycyrrhizin; quantified glycyrrhizin trial is indirect species evidence. with Oral clozapine treatment.
- Medication form and route
- oral clozapine; oral supplement
- Timing or duration
- No pair-specific duration threshold is established.
What remains uncertain
- Separate medication and supplement evidence supports a precaution; it does not establish additive hypertension, a safe dose or a pair-specific effect size.
Factors that may matter: glycyrrhizin content; existing hypertension; low potassium; heart or kidney disease.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral clozapine tablets.
Low potassium and magnesium increase QT-prolongation risk. The label describes electrolyte assessment and correction and lists hypertension among reported adverse reactions.
How this applies: Medication context for assessing glycyrrhizin-associated blood pressure and potassium effects; no proven additive hypertension from the combination.
Does not study or quantify an interaction with the exact supplement.
Source 2: regulatory herbal assessment
ema.europa.eu · Source check Sep 10, 2026
Population: Users of the specified oral liquorice-root preparations, including people susceptible to hypertension and electrolyte disturbances.
Recognizes blood-pressure increases and potassium loss; use is not recommended in hypertension, kidney, liver or cardiovascular disorders or hypokalaemia.
How this applies: Applies to the explicitly included G. glabra root preparations containing glycyrrhizin; combined clozapine risk is inferred from separate electrolyte guidance.
Joint species assessment, not a clozapine coadministration study. Does not establish equivalence across species, extracts or deglycyrrhizinated products.
Source 3: randomized crossover trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 28 healthy adults, median age 24 years.
Systolic home BP rose 3.1 mm Hg during licorice versus a -0.3 mm Hg change during control; renin and aldosterone were suppressed.
How this applies: Indirect evidence for glycyrrhizin-containing licorice effects, not a dose threshold or effect size for this exact pair.
Nonblinded trial; no clozapine exposure and abstract does not establish a botanically verified G. glabra product. Changes within periods are not a 3.1 mm Hg between-treatment effect.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Private evidence package and consumer draft prepared; clinical approval and publication are separate decisions. | |
| Research summary published |
Article revision: 85d0a48ea8878c93
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.