What effect does licorice have on blood pressure?

Licorice Consumption Significantly Raises Blood Pressure Through Mineralocorticoid Effects

Long-term consumption of licorice can cause hypertension through its mineralocorticoid activity, with even moderate intake of 100mg of glycyrrhizic acid daily being sufficient to significantly raise blood pressure. 1, 2

Mechanism of Action

Licorice contains glycyrrhizic acid (GA) and glycyrrhetinic acid which:

• Inhibits the type 2 isoenzyme of 11-beta-hydroxysteroid dehydrogenase (11β-HSD) 3
• Prevents local inactivation of cortisol in renal collecting tubules
• Increases cortisol binding to renal mineralocorticoid receptors
• Creates a state of pseudohyperaldosteronism 3

This results in:

• Sodium and water retention
• Hypokalemia
• Metabolic alkalosis
• Suppression of renin and aldosterone
• Elevated blood pressure

Magnitude of Blood Pressure Effects

Research demonstrates significant blood pressure elevations:

• 100g daily licorice consumption increased systolic BP by 6.5 mmHg on average (up to 19 mmHg in some individuals) 4
• Even 50g daily increased systolic BP by 5.6 mmHg and diastolic BP by 3.4 mmHg 4
• Recent research shows that just 100mg of glycyrrhizic acid daily (previously considered safe by WHO) increased systolic BP by 3.1 mmHg 2

Clinical Presentations

Licorice-induced hypertension can manifest as:

• Resistant hypertension unresponsive to standard treatments 3
• Hypertensive crisis requiring intensive care management 3
• Posterior reversible encephalopathy syndrome (PRES) in severe cases 5
• Laboratory abnormalities including hypokalemia, metabolic alkalosis, suppressed renin and aldosterone levels 3, 6

Risk Factors and Monitoring

The 2017 ACC/AHA hypertension guidelines specifically identify licorice as a substance that can elevate blood pressure 7. Patients at higher risk include:

• Those with pre-existing hypertension
• Older adults
• Patients with renal disease
• Individuals on antihypertensive medications

Management Recommendations

1. Identify licorice consumption in patients with unexplained or resistant hypertension 7
2. Discontinue licorice intake as the primary intervention
3. Monitor electrolytes, particularly potassium levels
4. Adjust antihypertensive medications as blood pressure normalizes after licorice cessation
5. Consider calcium channel blockers if continued licorice consumption is unavoidable 1

Clinical Pearls

• Blood pressure typically normalizes after discontinuing licorice consumption 3, 5
• Even modest licorice intake previously considered safe can raise blood pressure 2
• Patients may not recognize licorice as a potential cause of hypertension
• Laboratory findings of low potassium, low renin, and low aldosterone should raise suspicion for licorice consumption 3

In patients with cirrhosis and those on immunosuppressive medications, licorice consumption should be specifically avoided due to its mineralocorticoid and drug-drug interaction activities 7.