Licorice Root Side Effects

Licorice root is approximately 50 times sweeter than sugar. For thousands of years, licorice has been used in food and medicine and is Generally Recognized as Safe (GRAS) by the Food and Drug Administration (FDA). Glycyrrhizin and isoflavones are the active ingredients in licorice and are thought to mimic the action of steroid hormones and anti-inflammatory hormones such as hydrocortisone. Licorice root is used to treat stomach ulcers, nausea, coughs, viral infections, bronchitis, sore throat and eczema. In the March 24, 2004 issue of the "Cancer Letters," E. Jo and colleagues found that licorice root may also be preventive against breast cancer. Individuals consuming licorice root may experience side effects and the supplement may lose efficacy if used long-term.

Allergic Reaction

Glycyrrhizin can cause allergic reactions similar to other food-based allergens including hives, swelling, itching and mouth tingling. Supplements containing de-glycyrrhizinated licorice (DGL) have this allergen removed, thus they are safer and better tolerated. Individuals with multiple allergies should check with their physician prior to consuming licorice.

High Blood Pressure

In large amounts, glycyrrhizin-containing licorice may cause high blood pressure. In the August 2001 issue of the Journal of Hypertension, Sigurjónsdóttir and colleagues found that as licorice consumption increased so did blood pressure readings. Glycyrrhizin can lead to salt and water retention while depleting potassium levels. This electrolyte imbalance can lead to heart problems. These side effects may be reduced if the supplement is consumed intermittently as opposed to daily. A product made from DGL may also reduce these side effects. In addition, licorice may reduce the effectiveness of blood pressure-lowering medications or diuretics. Individuals with heart disease, high blood pressure, kidney disease, or liver disease should not consume licorice root.

Electrolyte Disturbances

Licorice root can have a laxative-like effect for some individuals and should not be consumed with other medications and/or over-the-counter products that also have laxative effects. The combination of these products may cause excess electrolyte excretion leading to dangerous potassium levels. Disturbances in electrolytes can lead to irregular heartbeat, heart attack, kidney damage, muscle weakness, and/or muscle breakdown.

Reproduction Problems

The National Institutes of Health (NIH) warns that licorice root can decrease testosterone levels in males and estrogen and prolactin levels in females. In the American Journal of Epidemiology, Timo E. Strandberg and colleagues discovered a link between licorice root consumption and lack of adequate hormones that can lead to difficulty in becoming pregnant or result in menstrual abnormalities. Women currently pregnant should not consume licorice root as it can increase risk of preterm labor. Licorice may also reduce the effects of birth control pills, hormone replacement therapies and testosterone therapy.

Vision Problems

High doses may cause vision problems or complete blindness according to the NIH. Excessive consumption of licorice root may cause obstruction of the central retinal vein which is the eye's main source of blood. If the central retinal vein becomes blocked, severe damage to the retina and blindness can result. Safety for long-term use has not been tested, so licorice root is only recognized as safe for four to six weeks.

Medication Interactions

If used with blood-thinning medications, antiplatelet drugs or aspirin, licorice may increase the risk of excess bleeding. Licorice root should also not be taken with cardiac glycosides, corticosteroids, diuretics, hormone therapy, insulin, laxatives, and monoamine oxidase inhibitors due to risk of serious side effects such as heart failure, electrolyte imbalances, coma and death.