Doctors have studied large numbers of people with epilepsy to find out how well gabapentin controls seizures. When it was used as an add-on with another seizure medicine, a number of adults had large reductions in their seizures, and side effects were not much trouble.

A similar study in children aged 3 to 12 years had similar results. The children with complex partial seizures and secondarily generalized seizures showed the greatest improvement.

Gabapentin is not the best add-on seizure medicine for everyone. Sometimes, a series of combinations must be tried before finding what is best for the individual. Gabapentin does have an advantage over some other medicines used for add-on therapy, because the doctor won't have to change how much of the first medicine is prescribed. The lack of interactions also makes gabapentin a good choice for people who need to take medicines for other disorders.

Some research also has looked at how well gabapentin works to control seizures when it is used alone. In one study, people with newly diagnosed partial seizures were treated with either gabapentin or another commonly used seizure medicine, carbamazepine (Tegretol, Carbatrol). The two medicines had just about the same effect on the seizures, but fewer people taking gabapentin had very troublesome side effects.