Keppra 100 mg/ ml oral opløsning indeholder metylparahydroxybenzoat (E218) og propylparahydroxybenzoat (E216) som kan medføre allergiske reaktioner (muligvis forsinket).
Suicide, suicide attempt, suicidal ideation and behaviour have been reported in patients treated with anti-epileptic agents (including levetiracetam).