How safe are dimenhydrinate suppositories? Seizures after accidental overdosage

History: A 13-month-old girl suffered from 3 generalized tonic-clonic seizures for several minutes within a total period of 9 hours. History revealed that the child received a total of 5 dimenhydrinate containing suppositories a 40 mg during the previous 2 days (i.e. 23 mg dimenhydrinate per kg body weight) due to enteritis with vomiting. The first seizure occurred 10 hours after the last administration. Investigations: The plasma level of diphenhydramin was 230 mu g/l approximately one hour after the first seizure. Electroencephalography showed no pathological signs, an MRI scan of the brain was normal except of several small gliotic spots and body temperature was regularly. Treatment and course: Two stationary occurring seizures were stopped with 5 mg diazepam rectally. Continued surveillance and an EEG two days later showed age-appropriate normal findings. There were no further seizures in the next 4 years. Conclusion: Infants have the risk to develop dimenhydrinate intoxication, especially in cases where suppositories were given repeatedly because of intermittent defecation.