Anticonvulsant hypersensitivity syndrome: clinical and laboratory features

Background Anticonvulsant hypersensitivity syndrome (AHS) is a severe adverse drug reaction with multiorgan involvement. Aromatic anticonvulsants are the most frequently involved drugs. This study was aimed to highlight the clinical and laboratory findings of AHS. Methods The medical records of 31 patients diagnosed as AHS in a 12-year period were evaluated retrospectively. Results The syndrome was related to carbamazepine in 48.38%, phenytoin in 35.48%, lamotrigine in 9.6% and cotreatment with lamotrigine and valproic acid in 6.45% of cases. Symptoms appeared 2-86 (mean: 35.96) days after ingestion of the offending agent. The type of skin rash was maculopapular and/or erythrodermic in 77.42% of patients, bullous in 19.35%, and erythematopustular in 3.22%. Fever and peripheral lymphadenopathy were detected in 61.29% and 54.82% of cases, respectively. Laboratory investigations revealed elevation of hepatic enzymes in 70.96%, leucocytosis in 43.3%, and peripheral eosinophilia in 64.3% of patients. Conclusions Our analysis showed that carbamazepine and phenytoin are still the major causes of AHS, with lamotrigine being the third etiologic agent. Valproic acid and benzodiazepines are safe alternatives of the causative anticonvulsants. As there are yet no strict diagnostic criteria, the constellation of clinical and laboratory features that occur within 3 months of the associated anticonvulsant agents helps to recognize the disorder. The risk of seizure due to withdrawal or changing of the anticonvulsant drug and the potentially serious clinical features often necessitates providing care and treatment in an inpatient setting.