(Ivanhoe Newswire) -- Licorice, a popular ingredient in a wide variety of foods and medicines, may block the effectiveness of a drug widely used by transplant recipients to prevent organ rejection.
Researchers said glycyrrhizin, the active ingredient in licorice, appears to block the absorption of cyclosporine, a drug that's given to transplant recipients and is used to treat rheumatoid arthritis, certain skin conditions and other diseases.
The scientists worry that this drug interaction could potentially result in organ rejection, causing illness and even death among patients who take cyclosporine and licorice together.
Previous studies have already shown that St. John's wort, onions, ginger, quercetin, and ginkgo reduce levels of cyclosporine in the body and should be avoided when taking the immunosuppressant drug.
Researchers said they still are not sure why licorice interferes with cyclosporine, but the study's authors are strongly urging transplant patients to avoid all licorice-based products.
Licorice is a popular herb that has been used for thousands of years in food and medicines. It's found in everything from candy to herbal teas to supplements designed to treat the common cold, stomach ulcers and liver disease.
Previous studies have shown that it can also interfere with the effectiveness of high blood pressure medications, aspirin, anti-inflammatory drugs, insulin and oral contraceptives.
SOURCE: Study presented at the American Chemical Society's 237th National Meeting on March 24, 2009