Can Olanzapine Cause Seizures?
Yes, olanzapine can cause seizures, although the risk is relatively low (approximately 0.9% of patients) when used at therapeutic doses. 1 The medication should be used cautiously in patients with a history of seizures or conditions that lower the seizure threshold.
Seizure Risk with Olanzapine
Olanzapine has been documented to lower the seizure threshold in a dose-dependent manner. According to the FDA drug label:
- Seizures occurred in 0.9% (22/2500) of olanzapine-treated patients during premarketing testing 1
- The risk may be higher in certain populations, particularly:
- Elderly patients (65 years or older)
- Patients with a history of seizures
- Patients with conditions that lower seizure threshold (e.g., Alzheimer's dementia)
Case Reports of Olanzapine-Induced Seizures
Several case reports have documented seizures associated with olanzapine use:
- Myoclonic status in a 54-year-old woman with probable Alzheimer's disease shortly after adding olanzapine 2
- Repetitive focal motor seizures with lingual dystonia in a psychiatric patient 3
- Generalized tonic-clonic seizures in a 71-year-old man within 24 hours of starting olanzapine at a subtherapeutic dose (1.25 mg twice daily) 4
- Status epilepticus in a 48-year-old woman after switching from quetiapine to olanzapine 5
- New-onset generalized tonic-clonic seizure in a 23-year-old female with mild mental retardation and schizophrenia 6
Risk Factors for Olanzapine-Induced Seizures
Several factors may increase the risk of seizures with olanzapine:
- Advanced age
- History of stroke or seizures
- Cognitive impairment/dementia
- Concomitant use of other medications that lower seizure threshold
- Higher doses of olanzapine
- Polypharmacy, particularly when combined with other psychotropic medications
Clinical Recommendations
When prescribing olanzapine, consider the following:
- Screen for seizure risk factors before initiating treatment
- Start with lower doses in patients with risk factors for seizures
- Monitor closely for any signs of seizure activity, especially during dose adjustments
- Use caution when combining with other medications that may lower seizure threshold
- Consider alternative antipsychotics in patients with a history of seizures or significant risk factors
Comparison to Other Atypical Antipsychotics
Clozapine has a higher seizure risk (approximately 5% at high doses) compared to olanzapine 7. The American Academy of Child and Adolescent Psychiatry notes that during a study of clozapine in youth with childhood-onset schizophrenia, two patients developed seizures, highlighting this risk 7.
Special Considerations
In patients with epilepsy or a history of seizures who require antipsychotic medication, careful monitoring and possibly prophylactic anticonvulsant therapy may be warranted when using olanzapine.
If a patient develops a seizure while on olanzapine, immediate discontinuation of the medication should be considered, especially if no other clear etiology for the seizure is identified.