Serotonin syndrome induced by tramadol intoxication in an 8-month-old infant

Severe cases of pediatric tramadol intoxication are rarely reported. We report on serotonin syndrome after tramadol intoxication. An 8-month-old girl developed extreme agitation after accidentally ingesting a tablet of her father's medication (Monocrixo LP (Thérabel Lucien Pharma, Levallois Perret, France), 200 mg tramadol). Unable to sleep, she was admitted the next morning to our Pediatric Emergency Department after an episode of epistaxis. Vital signs were significant for sinus tachycardia and a neurologic examination revealed intermediately reactive pupils, agitation alternating with drowsiness with a Glasgow Coma Scale of 10, and increased lower-limb reflexes. Within 24 hours, she developed hyperthermia and high blood pressure. She did not experience seizures. Neurologic and cardiovascular effects resolved on day 2. Tramadol serum plasma levels confirmed the intoxication (680 μg/L). She was discharged on day 5 with no sequelae. Serotonin syndrome was described in adults when tramadol was associated with selective serotonin-reuptake inhibitors in contexts of therapy or intoxication. Our patient developed moderate serotonin syndrome. The clinical presentation was unusual compared with previous pediatric cases of tramadol intoxication, in which opioid effects and seizures were usually predominant. This case illustrates that serotonin syndrome can occur in children intoxicated with tramadol.