Late cognitive effects of early treatment with phenobarbital

Clin Pediatr (Phila). 1999 Jul;38(7):387-94. doi: 10.1177/000992289903800702.


We previously reported that IQ was significantly lowered in a group of toddler-aged children randomly assigned to receive phenobarbital or placebo for febrile seizures and there was no difference in the febrile seizure recurrence rate. We retested these children 3-5 years later, after they had entered school, to determine whether those effects persisted over the longer term and whether later school performance might be affected. On follow-up testing of 139 (of the original n = 217) Western Washington children who had experienced febrile seizures, we found that the phenobarbital group scored significantly lower than the placebo group on the Wide Range Achievement Test (WRAT-R) reading achievement standard score (87.6 vs 95.6; p = 0.007). There was a nonsignificant mean difference of 3.71 IQ points on the Stanford-Binet, with the phenobarbital-treated group scoring lower (102.2 vs 105.7; p = 0.09). There were five children in our sample with afebrile seizures during the 5-year period after the end of the medication trial. Two had been assigned to phenobarbital, and three had been in the placebo group. We conclude there may be a long-term adverse cognitive effect of phenobarbital on the developmental skills (language/verbal) being acquired during the period of treatment and no beneficial effect on the rate of febrile seizure recurrences or later nonfebrile seizures.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Child
  • Humans
  • Intelligence Tests
  • Intelligence*
  • Male
  • Neurobehavioral Manifestations / drug effects*
  • Phenobarbital / pharmacology
  • Phenobarbital / therapeutic use*
  • Seizures, Febrile / drug therapy
  • Seizures, Febrile / physiopathology*


  • Phenobarbital