Febrile seizures are brief seizures lasting a few seconds to a minute or two that occur during a high fever. Children recover quickly after these events, which happen to 3 to 4 percent of children under 5 years of age. About one third of children with one febrile seizure will have another, and about one half of those children will have a third febrile seizure. Your child's history of four seizures is unusual but not unheard-of. Since your son had his first event before 18 months, he is in the group where recurrence is more likely. These harmless events scare parents and should be reported to the health care provider, but they rarely require any further investigation or treatment. When a child is susceptible to these seizures, watching for and promptly treating any fever is the main thing to do.
Review the seizure events with your child's health care provider to be sure they continue to have all the features of a simple febrile seizure. Be sure your son is doing well with development and growth. I don't know when your son's seizures will stop, but if he has an event after age 5, other kinds of seizures will need to be considered.