Black licorice is a candy made from an extract of the roots of Glycyrrhiza glabra, and has been used medicinally for hundreds of years. However, very high doses of licorice can cause headaches, fatigue, high blood pressure or heart attack.
Some conditions reported to benefit from licorice are peptic ulcers, canker sores, eczema, indigestion and upper respiratory infections. One study found licorice may reduce body fat. Licorice should not be given to children more than once a day and never given to infants. Those suffering from heart conditions, high blood pressure, liver disease, diabetes, hormone-sensitive cancers or kidney disease should not consume licorice.