Although the Food and Drug Administration (FDA) has not officially approved zonisamide for children, there have been quite a few research studies in which it has been given to children of various ages (even infants) with generally good results. It has been effective in reducing many types of seizures, especially partial seizures, primarily generalized seizures, absence seizures, infantile spasms, and myoclonic seizures.

Doctors figure out how much medicine to give to young children based mostly on their weight. To keep side effects at a minimum, the doctor probably will prescribe a low dose to start with and increase it slowly. Children usually start with a dose 1 to 2 milligrams (mg) per kilogram (kg) per day. A kilogram equals 2.2 pounds, so a 50-pound child weighs about 23 kilograms and would be started on approximately 25 to 50 mg of zonisamide each day. The doctor would then increase the dosage by a similar amount every 2 weeks, depending on how well the child's seizures are controlled and whether any side effects have appeared. Most children do best at about 8 mg per kg per day (184 mg for a 50-pound child). The highest dose recommended is 12 mg per kg per day.

The most common side effects in studies of children involved problems with thinking or behavior, followed by stomach upset. One dangerous side effect, decreased sweating with fever, occasionally affects young children but not adults. It is quite unusual but is worth watching out for, especially in summer. Parents whose children are given zonisamide should also watch for the other symptoms of rare but serious reactions that are listed on the serious side effects page.