Much of what's called "licorice" actually contains little to no licorice. Licorice, produced from the roots of the plant Glycyrrhiza glabra, contains the active ingredient glycyrrhizin, which has properties similar to aldosterone, a hormone released by the adrenal glands to regulate blood pressure. Black licorice candy may contain some licorice, but many black licorice products contain anise, which has a similar taste, rather than actual licorice. Black licorice that contains actual licorice may have a mild laxative effect. Actual licorice can have serious side effects; do not consume large amounts without your doctor's approval.
Licorice root extract is used in alternative medicine as a laxative, a diuretic and an anti-inflammatory agent. It is also used to treat gastric ulcers, respiratory problems such as asthma and bronchitis and skin conditions such as eczema and canker sores.
Laxative Side Effects
When taken with stimulant laxatives, licorice can increase potassium loss, according to the University of Maryland Medical Center. Consuming black licorice that contains glycyrrhetinic acid alone can also lower potassium levels, according to PubMed Health. Symptoms of low potassium include fatigue, muscle weakness, abnormal heart rhythms, paralysis and constipation. Mild hypokalemia is treated with potassium supplements, while very low potassium levels may require intravenous potassium and hospitalization.
In large quantities, 20 g per day or more, black licorice candy that contains glycyrrhizin can cause pseudoaldosteronism, which causes sensitivity to the hormone aldosterone. Symptoms include fluid retention, high blood pressure, headaches, fatigue and swelling of the arms and legs. People with heart or kidney conditions, diabetes or liver disease should not consume black licorice candy that contains actual licorice. Pregnant or breastfeeding women should not consume actual licorice products either.
Black licorice candy that contains actual licorice may have a mild laxative effect, but large quantities can cause serious side effects. Black licorice candy that contains actual licorice is no longer produced in the United States, according to PubMed Health, but imported candy may contain actual licorice. Licorice should not be taken for more than four to six weeks, the University of Maryland Medical Center advises.