Side effects of phenobarbital in toddlers; behavioral and cognitive aspects.

Cognitive and behavioral effects of phenobarbital in toddlers were assessed in a randomized, placebo-controlled study of patients who had had a febrile seizure. There were no significant differences in IQ (Binet or Bayley Scales) between placebo and phenobarbital groups after eight to 12 months of therapy. However, detrimental effects of phenobarbital were found in memory, for which serum level influenced scores, and in comprehension, in that length of treatment time affected performance. Hyperactivity was not seen. Behavioral changes, reported by parents, were increased fussiness and a characteristic disturbance of sleep. These changes varied in severity and were classified as transient, dose related, or unacceptable. After 12 months in the study, most parents could not distinguish between phenobarbital and placebo. Our data suggest that although most toddlers do not have major side effects from phenobarbital therapy when treated for a year, serum levels and length of time on phenobarbital should be kept at a minimum to reduce negative cognitive and behavioral effects.