In a number of randomized, controlled clinical trials, Keppra (at doses of 1000 to 3000 mg/day) has been significantly more effective than a placebo for patients with frequent partial seizures. Between 21% and almost 40% of the patients who took Keppra as add-on therapy reduced their seizure frequency by half or more, without excessive adverse side effects (Shorvon et al. 2000). The rate of side effects was lower than reported for most other seizure medicines.

At least one study has found that Keppra also may be effective when used alone to treat partial seizures (Ben-Menachem & Falter, 2000). Keppra was first given as add-on therapy, and the other antiepileptic medications were gradually withdrawn from patients whose seizure frequency was reduced by at least half. More than half of these patients continued at least a 50% reduction in seizure frequency with Keppra alone.