In 1999, Topamax was approved by the FDA to treat partial-onset seizures in children over 2 years of age. In 2001, it was approved to treat children with the Lennox-Gastaut syndrome. In both instances, it is recommended as an adjunctive medication, but it can also be used as monotherapy. Doctors also commonly prescribe it (either as adjunctive therapy or monotherapy) for children with primary generalized tonic-clonic seizures. Its effectiveness in treating children with myoclonic epilepsy is less well established, but evidence suggests that it can be useful.

If the dosage is increased slowly and carefully monitored, side effects should not be a problem for most children. The most common side effects involve problems with thinking or behavior, such as difficulty with concentration and attention or memory difficulty. These side effects may be less frequent in children than in adults. Headache, sleepiness, fatigue, and weight loss are other common side effects. Children are also susceptible to glaucoma.

Oligohidrosis has been described in children taking Topamax. Children should be monitored in hot weather to be sure they sweat appropriately.

Children often have the fewest problems from side effects with Topamax if they start at a dose of 15 to 25 mg or less, based on a range of 1 to 3 mg/kg per day. This dose is given nightly for the first week. The dose should then be increased every week or two by adding 1 to 3 mg/kg per day (given in two divided doses) to achieve the best response. Most children do best at about 5 to 9 mg/kg per day.

One advantage of using Topamax for children is that it comes in the form of a sprinkle capsule, which can be swallowed whole or given by carefully opening the capsule and sprinkling the entire contents on a small amount (teaspoon) of soft food. This mixture should be swallowed immediately and not chewed.