The short answer
Licorice containing glycyrrhizin can raise blood pressure and work against blood-pressure treatment. Avoid starting it without prescriber advice while taking prazosin; a dose gap has not been shown to prevent this effect.
What this answer covers
Oral prazosin with glycyrrhizin-containing Glycyrrhiza glabra root or stolon products. Deglycyrrhizinated licorice and other plant parts are not assumed equivalent.
- Supplement or preparation
- Glycyrrhiza glabra
- Medication ingredient
- prazosin
Why licorice is a concern
The current European assessment states that licorice can raise blood pressure and counteract antihypertensive medicines. It can also cause fluid retention and potassium loss. This is a concern about the body’s response to licorice, not proof that it blocks absorption of prazosin.
What a human trial adds
A randomized study in 28 healthy adults found increased home systolic pressure and suppressed renin and aldosterone after two weeks of licorice supplying 100 mg daily of glycyrrhizic acid. It did not test prazosin or establish a universally safe amount.
Identify the exact licorice product
Check root extracts, teas and combination products for licorice and glycyrrhizin. Deglycyrrhizinated licorice has a different constituent profile, and an unspecified botanical label cannot establish equivalence. Have the pharmacist review the product before use rather than choosing a timing gap.
When to contact your care team
Report a rise in your usual BP readings, new swelling, weakness or palpitations promptly. Your clinician may assess electrolytes and reconsider the licorice exposure. Do not increase prazosin or add potassium on your own to compensate for an unreviewed supplement.
Evidence and practical considerations
Side effects & toxicity
Glycyrrhizin-containing licorice can oppose antihypertensive treatment through BP and electrolyte effects, without proving reduced prazosin absorption.
- Exact scope
- Oral prazosin with glycyrrhizin-containing Glycyrrhiza glabra root or stolon products. Deglycyrrhizinated licorice and other plant parts are not assumed equivalent. with Current RxNorm confirms prazosin RxCUI 8629 IN. Hydrochloride polyhydrate capsules provide the equivalent of prazosin 1, 2 or 5 mg. Oral formulation only.
- Medication form and route
- Oral
What remains uncertain
- Regulatory class-level PD precaution plus supplement trial; no measured exact-pair PK, absorption decline, universal threshold or validated spacing.
Factors that may matter: Exact preparation and dose; Blood pressure and symptoms; Treatment initiation or dose change; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed prazosin hydrochloride capsules.
Postural hypotension, fainting and drowsiness can occur, particularly with initiation, dose escalation or additional BP-lowering medication.
How this applies: Exact ingredient through the stated labeled salt and oral formulation. Current RxNorm confirms prazosin RxCUI 8629 IN. Hydrochloride polyhydrate capsules provide the equivalent of prazosin 1, 2 or 5 mg. Oral formulation only.
No botanical interaction established merely by these drug-alone warnings.
Source 2: Final regulatory assessment
ema.europa.eu · Source check Sep 10, 2026
Population: Users of defined licorice root and stolon preparations.
Mineralocorticoid effects can cause potassium loss, fluid retention and hypertension. Explicitly states licorice may counteract antihypertensive action.
How this applies: Conditional pharmacodynamic bridge from glycyrrhizin-containing G.glabra root to BP-lowering medication.
Not a measured prazosin absorption or concentration study; deglycyrrhizinated products and unspecified plant parts differ.
Source 3: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 28 healthy young adults in a randomized crossover.
Home systolic BP rose and renin/aldosterone were suppressed.
How this applies: Exact preparation and endpoint boundaries retained; this is not a measured prazosin combination unless explicitly stated.
Abstract-only; no prazosin co-use. Product amount does not establish a safe limit for every licorice preparation.
Source 4: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology.
prazosin is IN.
How this applies: Exact ingredient.
Not clinical evidence.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources checked and article drafted. | |
| Research summary published |
Article revision: e6bb2e81123ca342
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.