A seizure is an involuntary behavior that occurs abnormally and are generally associated with epilepsy, but can come from other sources. Epileptic seizures are categorized by the location in the brain from which they originate and the two main categories of epileptic seizures are "partial" and "generalized." Partial seizures begin in a discreet area of the brain. A simple partial seizure causes no change in consciousness. The patient may have weakness, numbness and unusual smells or tastes. Sometimes, there is twitching of the muscles or limbs, head turning from side to side, paralysis, sight changes or vertigo.

Complex partial seizures occur in the temporal lobe and consciousness is altered. The patient usually has a change in their ability to interact with their environment and may exhibit automatic behaviors such as walking in a circle, sitting and standing, or smacking their lips. Often, odd thoughts occur to the patient, such as a feeling of déjà vu or uncontrollable laughing or odd smells.

Generalized seizures take place in larger areas of the brain and there are many sub-types. Grand mal seizures include specific movements of the arms and legs or face and may occur with a loss of consciousness. Sometimes there is yelling or crying before the person faints. They may also experience an aura, which is an unusual feeling that often warns the patient that seizure is coming on. The patient abruptly falls and begins to jerk and may become incontinent or drool or bite their tongue. This type of seizure usually lasts between 5 and 20 minutes and the patient may awake in a confused state or may sleep for a while. Sometimes, the patient has prolonged weakness after the event.

Petit mal seizures include a brief loss of consciousness but there is not associated motor dysfunction and there is no aura prior to the seizure. Sometimes it just seems that the person is briefly stopping what they were doing, staring for a few seconds, and then continuing with their activity. The patient does not even have any memory of the event.