Cyclosporine is also used to treat. "I would suggest that transplant patients avoid taking licorice," researcher Pei-Dawn Lee Chao, a chemist at China Medical University in Taichung, Taiwan, said in an American Chemical Society news release. Sign Up for MedicineNet Newsletters. For a transplant patient on cyclosporine, lowered levels of the medication could lead to rejection of the new organ, follo by illness and even death, said the researchers, who were to present their findings at the American Chemical Society's annual meeting in Salt Lake City. Chemists in Taiwan report that lab rats taking cyclosporine -- commonly used to help prevent organ rejection in transplant patients -- who were feed licorice or its main active ingredient, glycyrrhizin, did not absorb the medication well. Licorice Weakens Organ Transplant Drug FDA Panel Backs New Anti-Clotting Drug Genetics Should Decide Warfarin Dose, Says Study Admissions for Prescription Painkiller Abuse Rise Patients, Doctors Don't Discuss Rx Prices Want More News.

The researchers, who are trying to determine why licorice interfered with the drug's absorption, said they didn't know how much licorice might cause a toxic reaction in humans.