Licorice and blood pressure: potassium, interactions and who's at risk

Glycyrrhizin, or glycyrrhizic acid, has mineralocorticoid-like effects. In practice, the body retains more sodium and water and eliminates more potassium. Blood pressure rises, and blood potassium can drop.

These effects don't apply to every confectionery or every flavoring: some "licorice-flavored" products use other flavorings, and the actual glycyrrhizin content varies widely. For the different forms and regulatory thresholds, see our article on licorice root and glycyrrhizin.

Repeated exposure can lead to:

• a rise in blood pressure, sometimes with headaches;
• a drop in potassium (hypokalemia), which shows up as muscle weakness or cramps;
• swelling (edema);
• palpitations or heart rhythm disorders.

According to the NCCIH, the US agency for complementary and integrative health, glycyrrhizin can cause rhythm disorders, even cardiac arrest, especially in large amounts or over a long period. Even modest amounts have been associated with serious effects in people who eat a lot of salt, have high blood pressure, or have heart or kidney disease.

Extra caution is needed with:

• high blood pressure or cardiovascular disease;
• kidney or liver disease;
• potassium that is already low, or a treatment that lowers potassium;
• a diet high in salt;
• pregnancy or breastfeeding;
• young age.

During pregnancy, the NCCIH considers consuming about 250 g of licorice per week to be dangerous, and links large amounts of extract to a risk of delivery before 38 weeks. Data on breastfeeding are limited.

The most concerning interactions involve medications that affect potassium or blood pressure:

• Diuretics (thiazide, loop): these already cause potassium loss; combining them with licorice can worsen hypokalemia.
• Blood pressure medications: licorice can counteract their effect by raising blood pressure.
• Corticosteroids: the NCCIH notes reported interactions; effects on sodium and potassium can add up.
• Digoxin: low potassium increases the risk of toxicity from this medication.

The exact list depends on the product and the dose. Before any regular use, give your pharmacist or doctor the botanical name, the form, the stated glycyrrhizin content, and your complete medication list. Never stop or change a medication in order to take licorice.

Licorice root has a traditional use, recognized by the European Medicines Agency (EMA), for certain digestive complaints such as heartburn and dyspepsia, and for cough linked to a cold. This doesn't prove that every extract relieves reflux, ulcers, or a digestive disease. A Cochrane review on non-Chinese herbal medicines in functional dyspepsia in fact judges the data insufficient.

Deglycyrrhizinated licorice (DGL) limits the effect on blood pressure; according to the NCCIH, oral products of this type appear to be safe for up to four months. Their composition should still be checked.

Persistent digestive pain, repeated vomiting, blood in the stool, weight loss, or difficulty swallowing call for medical evaluation, not self-medication.

The duration of use depends on the preparation and the indication. An infusion, a root, a tincture, a dry extract, and a deglycyrrhizinated product are not interchangeable. European monographs regulate specific preparations and durations; they do not validate continuous use of just any product.

Prolonged or repeated use of licorice containing glycyrrhizin should be avoided without professional advice. "Natural" doesn't mean compatible with daily use for months.