There are roughly 21 recognized types of seizures, organized into four main categories: focal, generalized, unknown, and unclassified. The International League Against Epilepsy (ILAE), the organization that sets the global standard for seizure classification, established its framework in 2017 and updated it in 2025 to streamline the system from 63 types down to 21.
The number can feel overwhelming, but the system follows a simple logic. Every seizure is first sorted by where it starts in the brain, then by what it looks like physically. Understanding the main categories and the most common types within each one covers what most people need to know.
The Four Main Categories
A seizure is classified first by its point of origin. Focal seizures start in one hemisphere of the brain. Generalized seizures appear to fire across both hemispheres simultaneously. When doctors can’t determine where a seizure began, it’s labeled unknown. And when a seizure doesn’t fit neatly into any group, it’s classified as unclassified.
In a long-running study of new epilepsy cases in Rochester, Minnesota, about 57% of people had focal seizures, 23% had generalized tonic-clonic seizures, and the rest had other generalized or unknown types. So focal seizures are actually the most common form, even though the dramatic, full-body convulsions most people picture are generalized seizures.
Focal Seizures
Focal seizures begin in a specific area of one side of the brain, and their symptoms depend entirely on which region is involved. They’re divided further based on whether a person stays aware during the event.
Focal aware seizures (previously called simple partial seizures) leave consciousness intact. You know the seizure is happening. You might experience a strange taste, a wave of fear, tingling in one hand, or jerking in one arm, but you remain alert and can remember it afterward.
Focal impaired awareness seizures (previously called complex partial seizures) affect consciousness. You may stare blankly, fumble with your clothing, smack your lips, or wander without purpose. Afterward, you typically have little or no memory of what happened.
Either type of focal seizure can also spread to involve the whole brain, producing convulsions. When this happens, it’s called a focal to bilateral tonic-clonic seizure. It starts on one side but ends up looking like a generalized seizure.
Generalized Seizures
Generalized seizures engage both sides of the brain from the start. They split into two broad groups: motor seizures, which involve movement, and non-motor seizures, which don’t.
Generalized Motor Seizures
Tonic-clonic seizures are what most people think of when they hear the word “seizure.” Once called grand mal seizures, they cause the body to stiffen (the tonic phase) followed by rhythmic jerking (the clonic phase). They typically last a few minutes and leave a person confused and exhausted afterward.
Tonic seizures involve only the stiffening. Your muscles suddenly tense up, often in the back, arms, and legs, which can cause you to fall if you’re standing.
Clonic seizures involve only the rhythmic jerking, without the initial stiffening phase. These are less common on their own.
Myoclonic seizures produce brief, sudden jerks of a muscle or muscle group. They feel like being jolted with electricity. Each jerk typically lasts only a second or two, though multiple episodes can cluster together in rapid succession.
Atonic seizures do the opposite. Instead of muscles contracting, they suddenly go limp. This can cause your head to drop, your knees to buckle, or your whole body to collapse. They’re sometimes called “drop attacks” for this reason.
Generalized Non-Motor (Absence) Seizures
Absence seizures, once called petit mal seizures, cause brief lapses in consciousness. A person may stare blankly for a few seconds, blink rapidly, or make small movements like lip smacking. They’re so subtle they often go unnoticed, especially in children, where they’re most common. A child having dozens of absence seizures a day may simply appear to be daydreaming or not paying attention in class.
Unknown and Unclassified Seizures
Sometimes there isn’t enough information to determine where a seizure started. The person may have been alone, or the seizure may have begun during sleep. These are placed in the “unknown” category. Unknown seizures can still be further described as motor or non-motor based on what was observed.
The “unclassified” category exists for seizures that don’t fit the other three groups even with adequate information. This is a small category, but it keeps the system from forcing a seizure into a box where it doesn’t belong.
When a Seizure Becomes an Emergency
Most seizures end on their own within a few minutes. When a seizure lasts longer than five minutes, or when someone has repeated seizures without fully recovering between them, it becomes a condition called status epilepticus. This is a life-threatening emergency that requires immediate medical intervention. The five-minute threshold is the key number to remember.
Non-Epileptic Seizures Look Similar but Have Different Causes
Not all seizures are epileptic. Psychogenic non-epileptic seizures (PNES) produce visible symptoms that closely resemble epileptic seizures, including convulsions, apparent loss of consciousness, and behavioral changes. The difference is that they aren’t caused by abnormal electrical activity in the brain. They’re driven by psychological factors, often related to stress, trauma, or emotional distress.
Several features can help distinguish the two. Non-epileptic seizures tend to last longer, averaging around 4.5 minutes compared to about 1.5 minutes for epileptic seizures. They may involve a fluctuating course, side-to-side head movements, closed eyes, or emotional expressions like crying. They don’t occur during confirmed sleep. Epileptic seizures, by contrast, are more likely to be followed by genuine confusion and heavy, labored breathing. Still, the overlap is significant enough that a definitive diagnosis often requires brain monitoring to check for the electrical patterns that define epileptic activity.