Adverse Effects of Levetiracetam

Comparative Safety Profile

The American Heart Association recommends levetiracetam over phenytoin or valproic acid due to its better tolerability, with lower incidence of adverse effects in patients with aneurysmal subarachnoid hemorrhage, as measured by Glasgow Outcome Scale-Extended and Disability Rating Scale 1
The American Academy of Neurology suggests that phenytoin causes poorer cognitive outcomes and excess morbidity, prompting the use of alternative antiseizure medications like levetiracetam 1

The National Institute of Neurological Disorders and Stroke advises that dose adjustments are necessary in patients with renal dysfunction due to predominant renal elimination, although no specific citation is provided, a study published in the Annals of Emergency Medicine found that in status epilepticus studies using doses up to 2,500 mg IV, only isolated cases of nausea and transient transaminitis were noted 2
The American College of Emergency Physicians notes that no serious adverse effects were attributable to rapid infusion at 5 mg/kg per minute in status epilepticus studies 2

When used for oral loading in patients with epilepsy, 89% of patients reported no adverse effects, while 11% experienced transient irritability, imbalance, tiredness, or lightheadedness 3, 4, 5
Levetiracetam is generally better tolerated than older antiepileptic drugs like phenytoin or valproic acid, according to the American Academy of Neurology 6

Dose adjustments may be necessary in patients with renal dysfunction, as recommended by clinical guidelines 7

In patients with aneurysmal subarachnoid hemorrhage, levetiracetam was associated with a significantly lower incidence of adverse effects—as measured by the Glasgow Outcome Scale‑Extended and the Disability Rating Scale—than phenytoin or valproic acid, indicating superior tolerability. 8
The American Heart Association recommends levetiracetam over phenytoin for seizure prophylaxis in this setting because phenytoin is linked to poorer cognitive outcomes and higher overall morbidity. 8

Among individuals undergoing brain tumor surgery, levetiracetam demonstrated better tolerability than older antiepileptic drugs while providing comparable efficacy for preventing early postoperative seizures within the first 7 days. 9
In the same population, valproic acid has been associated with hepatotoxicity and thrombocytopenia, especially when patients receive concurrent chemotherapy, highlighting levetiracetam’s advantage of minimal organ toxicity. 9

For women who may become pregnant, levetiracetam is strongly preferred over valproic acid because valproic acid carries a markedly higher risk of fetal malformations and adverse neurodevelopmental outcomes. 9

Levetiracetam’s metabolism is independent of the cytochrome P450 enzyme system and it does not induce these enzymes, resulting in minimal drug‑drug interactions—a contrast to valproic acid, which has extensive CYP‑mediated interactions. 9