What Are Seizures and How Do They Relate to Epilepsy?

Updated

A seizure is a temporary change in behavior, sensation, or awareness caused by abnormal electrical activity in the brain. Having one seizure does not mean a person has epilepsy: epilepsy is diagnosed when a person has a continuing tendency to have unprovoked seizures, generally defined as at least two seizures occurring more than 24 hours apart without a known reversible cause. The distinction matters because it determines whether someone needs ongoing treatment or only evaluation of a one-time event.

What Happens During a Seizure

Brain cells normally communicate through controlled electrical signals. During a seizure, a group of cells fires abnormally and excessively, either in one area or across the whole brain. The symptoms depend entirely on where that activity starts and how far it spreads, which is why seizures look so different from person to person.

Common patterns include:

  • Focal seizures starting in one part of the brain. A person may stay aware but experience unusual sensations, smells, emotions, or involuntary movements of one body part, or awareness may be impaired.
  • Generalized seizures involving both sides of the brain from the start. These include tonic-clonic seizures (stiffening followed by rhythmic jerking and loss of consciousness) and absence seizures (brief staring spells with lapses in awareness).
  • Subtle presentations such as brief confusion, repetitive movements like lip-smacking or fumbling, or a sudden unexplained fall.

Seizures usually last from a few seconds to a couple of minutes. Most stop on their own.

Seizures vs. Epilepsy: The Key Difference

Question Seizure Epilepsy
What is it? A single event of abnormal brain electrical activity A condition of recurring unprovoked seizures
How is it identified? Observed symptoms plus medical evaluation Typically two or more unprovoked seizures more than 24 hours apart
Can it occur without the other? Yes — many causes are reversible No — epilepsy is defined by the tendency to have seizures
Typical next step Find and treat the cause Ongoing management, often with medication

Seizures can be provoked by factors that are not epilepsy, including very low blood sugar, high fever (especially in young children), alcohol withdrawal, severe sleep deprivation, head injury, or certain medications. When the trigger is corrected, the seizures usually stop and epilepsy is not diagnosed. A doctor may also diagnose epilepsy after one seizure if tests such as an EEG or MRI show a clearly high risk of another.

When a Seizure Is an Emergency

Call emergency services if any of the following occur:

  • The seizure lasts longer than five minutes.
  • A second seizure begins before the person recovers from the first.
  • The person does not regain normal breathing or consciousness after the seizure ends.
  • The seizure happens in water, or the person is injured, pregnant, or has diabetes.
  • It is the person's first known seizure.

Prolonged or repeated seizures without recovery can be life-threatening and need urgent treatment.

What to Do While Someone Is Having a Seizure

  1. Keep the person safe. Ease them to the floor if they are standing, and move hard or sharp objects away.
  2. Time it. Note the start time so you can report duration accurately.
  3. Turn them on their side once jerking stops or if there is vomiting, to keep the airway clear.
  4. Do not restrain the person, put anything in their mouth, or try to give food or drink until they are fully alert.
  5. Stay until recovery. After a seizure, people are often confused, tired, or have a headache for minutes to hours. Speak calmly and let them rest.
  6. Record what you saw — what happened before, during, and after — because this description is often more useful to a doctor than any test.

When to See a Doctor and What to Track

Anyone with a first-time seizure should be medically evaluated. Seek prompt care for new or changing seizure patterns, seizures that interfere with daily life, or side effects from medication.

A seizure diary helps clinicians distinguish seizure types and judge whether treatment is working. Useful entries include:

  • Date and time of each event
  • What the person was doing beforehand (sleep, missed meals, stress, illness, alcohol)
  • What the seizure looked like and how long it lasted
  • How the person felt and behaved afterward
  • Any medication doses missed

For people already diagnosed with epilepsy, this record supports decisions about medication adjustments. For anyone else, it helps a doctor decide whether the event was a provoked seizure, whether further testing is needed, and whether the pattern suggests epilepsy. The Epilepsy Foundation (epilepsy.com) provides patient education and community discussion forums that can help people prepare questions for that conversation.