Dose-related side effects
In clinical studies performed before its approval by the FDA, Keppra (levetiracetam) was given to 769 patients who were already taking another seizure medicine, and only 15% of them stopped taking Keppra or lowered their dosage because of side effects, compared to 11.9% of the 439 patients who received a placebo. More recent studies have shown similar numbers and Keppra has now been used by at least 100,000 patients. It continues to have an excellent safety profile.

The side effects that were reported more frequently with Keppra than with placebo during the clinical trials were:

• sleepiness
• asthenia (loss of strength and energy)
• dizziness
• infection

These occurred mostly during the first 4 weeks of treatment. The infections were mainly colds (upper respiratory infections) and infection has not been a problem during recent experience with large numbers of patients.

Some other side effects mentioned even less often have included:

• agitation
• anxiety
• other mood changes
• coordination difficulties
• headache

Some doctors have observed behavioral problems. These were more frequent in children than in adults.