On October 30, 2017, the FDA warned consumers that eating 2 ounces of black licorice a day for at least two weeks could cause an irregular heart rhythm or arrhythmia in adults age 40 or older. 

The root of the licorice plant (Glycyrrhiza glabra) contains a compound called glycyrrhizin. Glycyrrhizin can lower potassium levels in the body, which can cause irregular heart rhythms, as well as high blood pressure, swelling, lethargy, and congestive heart failure.

(See the Warning about supplements, including licorice, which can cause or worsen heart failure).

The FDA advised consumers of all ages not to eat large amounts of black licorice at one time. The agency also warned that people who have been eating a lot of black licorice and experience an irregular heart rhythm or muscle weakness stop eating it and immediately and contact their healthcare provider.

When sold as a supplement, licorice root is often promoted for digestive issues such as heartburn and ulcers. Licorice supplements in which the glycyrrhizin has been removed, or deglycyrrhizinated, are available; these are typically labeled as deglycyrrhizinated licorice root, or "DGL." 

For more information about safety concerns with licorice, see ConsumerLab's CL Answer about licorice root tea.

See related Warnings:

Some Supplements May Cause or Exacerbate Heart Failure (Includes vitamin E and many herbs)

Morphine Found in Licorice Product

To read the FDA's warning, use the link below.