Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 13 3 2014 06 15 214 217 EN Zohra Chadly Department of Pharmacology, University Hospital, Monastir, Tunisia. Karim Aouam Department of Pharmacology, University Hospital, Monastir, Tunisia. Amel Chaabane Department of Pharmacology, University Hospital, Monastir, Tunisia. Hichem Belhadjali Department of Dermatology, University Hospital, Monastir, Tunisia. Naceur Abderrazzak Boughattas Department of Pharmacology, University Hospital, Monastir, Tunisia. Jamel Eddine Zili Department of Dermatology, University Hospital, Monastir, Tunisia. 2015 10 16 A-10-year-old girl was referred to our department for multiple hyperpigmented plaques. One  week  previously,  she  had  been  given  one  suppository  of  acetylsalicylic acid  – phenobarbital for fever. Twelve hours after the drug intake the child developed pruritic red plaques on the left thigh. Six weeks after resolution of the acute reaction, patch tests were performed separately, with phenobarbital and acetylsalicylic acid. On 48-hour reading, only the phenobarbital patch test on residual pigmented lesion was positive. Because of possible cross-reactions between aromatic anticonvulsants, subsequent  patch  tests using carbamazepine and phenytoin on residual pigmented lesions were performed. They were all negative at 48-hour reading. To our knowledge, only two isolated pediatric cases of Phenobarbital-induced FDE have been reported in the literature. In this case report, as it was difficult to determine whether phenobarbital or acetylsalicylic acid was responsible for this reaction, subsequent patch tests allowed the identification of the culprit component since it was positive to phenobarbital. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/454 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/454/383