Understanding Seizures
Types of Seizures
Seizures can affect movement, consciousness, sensations or behaviour. Explore the main seizure classes and find information about individual seizure types.
About this information: This webpage is subject to continuous review by Epilepsy Ontario to help keep the information current. Updates to linked pages may be in progress. This material is for informational purposes only and should not be used for self-diagnosis or as a substitute for professional medical advice, diagnosis or treatment. Consult your healthcare provider about your own health and care.
The Main Classes
How are seizures classified?
The International League Against Epilepsy’s 2025 classification uses four main classes. Your healthcare provider uses the available clinical information to classify your seizures.
Focal
Involves networks within one side of the brain. Consciousness may be preserved or impaired.
Generalized
Involves networks across both sides of the brain. Includes absence seizures and other generalized seizure types.
Unknown whether focal or generalized
Some seizure features are known, but there is not enough information to determine whether the seizure is focal or generalized.
Unclassified
The event is considered an epileptic seizure, but there is insufficient information to classify it further.
A note about terminology
ILAE’s 2025 update uses consciousness, assessed through awareness and responsiveness. Older resources may use “aware,” “impaired awareness,” “partial” or “dyscognitive.” Some linked pages still use these terms while we update them.
Ask your healthcare provider which terms describe your seizures. A seizure’s classification may change when more information becomes available.
Explore Focal Seizures
Focal Seizures
What a person experiences depends on the networks involved. A focal seizure can also spread to involve both sides of the brain, becoming a focal-to-bilateral tonic-clonic seizure.
Preserved consciousness
Explore the existing page titled “Focal Seizures with Retained Awareness.”
Explore Generalized Seizures
Generalized Seizures
Browse these seizure topics. Movement patterns such as stiffening or jerking can also occur in focal seizures, so the appearance alone does not establish the seizure class.
Absence Seizures
Brief interruptions in consciousness, often appearing as a pause or stare.
Tonic-Clonic Seizures
Seizures with stiffening followed by rhythmic jerking. They may be generalized or develop from a focal seizure.
Additional Topics
Important distinctions.
Infantile Spasms
Epileptic spasms can be focal, generalized or of unknown class. Suspected spasms in a baby need urgent medical assessment; prompt recognition and treatment are important.
Functional / Dissociative Seizures
Also called psychogenic non-epileptic seizures (PNES), these events can resemble epileptic seizures but are not caused by epileptic electrical activity. They require appropriate assessment and care.
Not sure which type applies?
Ask your healthcare provider to explain your seizure type and what it means for your care. Written descriptions of what happens before, during and after an episode can support that conversation.
Classification reference:
ILAE: Updated Classification of Epileptic Seizures (2025).
This page is an introduction, not a complete classification chart.
