A 10-year-old boy was admitted to hospital in Bologna, Italy after suffering a 2 minute tonic-clonic seizure. Dr Davide Tassinari and colleagues from the University of Bologna, Italy reported that a cluster of another three generalized seizures occurred in the next few hours. The boy also complained of a bad headache and had high blood pressure. Investigations were conducted using cranial computed tomography (CT) and magnetic resonance imaging (MRI), to investigate the possibility of posterior reversible encephalopathy syndrome (PRES). However, the major clinical conditions that lead to PRES were all ruled out.
During a medical examination a week later doctors noticed that the boy's teeth were black. It transpired that he had been eating at least 20 licorice sweets each day for the past four months. This resulted in the consumption of 2.88 mg/kg of glycyrrhizic acid (one of the active ingredients of licorice), well above the World Health Organization's recommended maximum of 2 mg/kg. This excessive consumption had resulted in his development of hypertension (or high blood pressure), and in turn PRES. After the boy stopped eating the sweets, his anti-hypertensive treatment was gradually reduced and his blood pressure returned to normal.
The authors note that the risk is particularly high for children with a low body weight. They recommend that licorice sweet manufacturers should state a recommended daily amount as a safety measure.
Citation: "Posterior reversible encephalopathy syndrome associated with licorice consumption: a case report in a 10-year-old boy" by Davide Tassinari MD, Rosalba Bergamaschi MD, Ilaria Corsini MD, Susanna Landini MD, Benedetta Romanin MD, Elisa Ballarini MD, Fabrizio De Ponti MD, Filomena Carfagnini MD, Francesco Toni MD, and Filippo Bernardi MD (doi:10.1016/j.pediatrneurol.2014.12.001 ); Pediatric Neurology