Approximately 30% to 40% of children who have a febrile seizure will
have a recurrence, usually within 12 months.
A higher risk of recurrence exists if the first seizure occurs when the patient is younger than 15 months, there is a history of FS in a first-degree relative, there is a shorter duration of fever prior to the seizure, and when the febrile seizure occurs at a lower temperature.
In contrast, the presence of a complex first febrile seizure, a history of developmental delay, and a family history of epilepsy have no influence on the recurrence rate of febrile seizures.
In addition, patients who have a febrile seizure lasting longer than 30 minutes had only a 2% risk of a second lengthy febrile seizure