Overview

A seizure is a sudden burst of electrical activity in the brain. It can cause changes in behavior, movements, feelings and levels of consciousness. Epilepsy is defined as having two or more seizures at least 24 hours apart that don't have a known cause. But epilepsy doesn't cause all seizures.

There are many types of seizures. They have a range of symptoms and vary in how much they affect your daily life. Seizure types also vary by where they begin in the brain and how far they spread. Most seizures last from 30 seconds to two minutes. A seizure that lasts longer than five minutes is a medical emergency.

Seizures can happen after a stroke or a head injury. An infection such as meningitis or another illness also may be the cause. But often the cause is not known.

Medicine can manage most seizures, but they can have side effects. Work with your healthcare professional to balance seizure management and medicine side effects.

Symptoms

Symptoms vary based on the type of seizure. They also can range from mild to serious. Seizure symptoms may include:

  • Short-lived confusion.
  • A staring spell.
  • Jerking movements of the arms and legs that can't be stopped.
  • Loss of consciousness or awareness.
  • Changes in thinking or emotions. These may include fear, anxiety or a feeling of already having lived the moment, called deja vu.

Most seizures fall into one of two classes called focal or generalized. The classes are based on how and where the brain activity causing the seizure began. If health professionals don't know how the seizures began, they may say the seizures are of unknown onset.

Focal seizures

Focal seizures result from electrical activity in one area of the brain. This type of seizure can happen with or without passing out, called losing consciousness.

  • Focal seizures with impaired awareness. These seizures involve a change or loss of consciousness or awareness that feels like being in a dream. During these types of seizures, people may seem awake. But they stare into space and don't respond to anything around them.

    They may repeat movements such as hand rubbing and mouth movements, repeat certain words, or walk in circles. They may not remember the seizure or even know that it happened.

  • Focal seizures without impaired awareness. These seizures may change emotions. They also may change how things look, smell, feel, taste or sound. But people having a focal seizure don't pass out.

    During these types of seizures, people may feel angry, joyful or sad. Some people have nausea or odd feelings that are hard to describe. These seizures may cause trouble speaking and jerking of a body part such as an arm or a leg. They also may cause sudden symptoms such as tingling, dizziness and seeing flashing lights.

Symptoms of focal seizures may seem like those of other conditions of the brain or nervous system. These other conditions include migraine, mental illness or a condition that affects how the brain manages sleep-wake cycles, called narcolepsy.

Generalized seizures

Seizures that appear to involve all areas of the brain from the time they start are called generalized seizures. Types of generalized seizures include:

  • Absence seizures. Absence seizures often happen in children. These seizures once were called petit mal seizures. People who have absence seizures most often stare into space or make slight body movements such as eye blinking or lip smacking. The seizures most often last for 5 to 10 seconds.

    Absence seizures can happen up to hundreds of times a day. They can come in clusters. And they can cause a brief loss of awareness.

  • Tonic seizures. Tonic seizures cause muscles to get stiff. These seizures most often affect muscles in the back, arms and legs. People who have these seizures may pass out and fall to the ground.
  • Atonic seizures. Atonic seizures cause a sudden loss of muscle use, most often in the legs. They're also called drop seizures. People having this type of seizure may collapse.
  • Clonic seizures. Clonic seizures are linked with jerking muscle movements. These seizures usually affect the neck, face and arms on both sides of the body.
  • Myoclonic seizures. Myoclonic seizures most often cause sudden brief jerks or twitches of the arms and legs. People who have these seizures don't often pass out.

  • Tonic-clonic seizures. Tonic-clonic seizures are the most common type of generalized seizure. They once were called grand mal seizures. They can cause passing out, body stiffness and shaking. They sometimes cause people to urinate or to bite their tongues.

    Tonic-clonic seizures last for several minutes. Tonic-clonic seizures may start as focal seizures that spread to involve most or all of the brain.

Seizure stages

Seizures can have a beginning phase, a middle phase and an end phase. These phases also are called prodrome, ictal and postictal.

  • Prodrome. This is the earliest warning that a seizure may happen. During the prodrome, people may have a hard-to-describe sense that a seizure may happen. They also may have changes in behavior. This can happen in the hours or even days before a seizure.

    The prodrome stage may include an aura. The aura is the first symptom of a seizure. Symptoms during the aura may include the feeling that a person or place is familiar, called deja vu, or a feeling that a person or place is not familiar.

    Or people may simply feel strange, feel fear or panic, or even have good feelings. Symptoms also may include smells, sounds, tastes, blurred vision or racing thoughts. Most often, auras are feelings that are hard to describe. The prodrome may include headache, numbness, tingling, nausea or dizziness.

    Many people with seizures have a prodrome or aura. But some people do not.

  • Ictal phase. The ictal phase lasts from the first symptom, including the aura, to the end of the seizure. Symptoms of the ictal phase depend on the type of seizure.

  • Postictal phase. This is the period after a seizure during recovery. The postictal stage can last minutes or hours. Some people recover quickly, while others take hours. The length of the postictal phase depends on the type of seizure and what part of the brain was affected.

    During this phase, people may be slow to respond, have trouble with memory, and have trouble talking or writing. They may feel sleepy, confused, dizzy, sad, scared, anxious or frustrated. They also may have nausea, a headache or weakness. They may feel thirsty or urinate.

When to see a doctor

Seek medical help right away if you have a seizure or if you see someone have a seizure and any of the following happens:

  • The seizure lasts more than five minutes.
  • The person isn't breathing after the seizure stops.
  • A second seizure follows right away.
  • The person has a high fever.
  • The person's body overheats, called heat exhaustion.
  • The person is pregnant.
  • The person has diabetes.
  • The seizure causes an injury.
  • The seizure happens in water.

The first time you have a seizure, see a healthcare professional.

Causes

Seizures are caused by changes in the way nerve cells in the brain communicate. Nerve cells in the brain create, send and receive electrical impulses. The nerve cells are called neurons. The impulses allow the cells to communicate. Anything that gets in way of the communication pathways can lead to a seizure. Gene changes cause some types of seizures.

Epilepsy is a common cause of seizures. But not everyone who has a seizure has epilepsy. Sometimes the following can cause seizures:

  • A high fever. When fever causes a seizure, it's called a febrile seizure.
  • An infection of the brain. This may include meningitis or encephalitis.
  • Serious illness. This includes serious illness with COVID-19.
  • Lack of sleep.
  • Low blood sodium. This can happen if you take medicine that makes you urinate.
  • Certain medicines that treat pain or depression or help people stop smoking.
  • A new, active brain injury, such as head trauma. It can cause bleeding in an area of the brain or a stroke.
  • The use of drugs that are sold on the streets. This includes amphetamines and cocaine.
  • Alcohol misuse. Seizures can happen from withdrawal from alcohol or from drinking too much alcohol.

Risk factors

The following increase the risk of having a seizure:

  • Head or brain injuries.
  • Cognitive issues.
  • Stroke.
  • Alzheimer's disease.
  • Brain tumors.
  • Alcohol or illicit drug misuse.
  • Family history of seizures.

Complications

Having a seizure can sometimes lead to complications that can cause danger for you or others. You might be at risk of:

  • Falling. If you fall during a seizure, you can injure your head or break a bone.
  • Drowning. If you have a seizure while swimming or bathing, you're at risk of drowning.
  • Car accidents. A seizure can cause loss of awareness or not being able to control a vehicle while driving.
  • Pregnancy complications. Seizures during pregnancy pose dangers to pregnant people and their babies. And certain antiseizure medicines increase the risk of health conditions present at birth. If you have epilepsy and plan to become pregnant, work with your healthcare professional to check to see if your medicines need to be adjusted during pregnancy.
  • Mental health conditions. People with seizures are more likely to have depression, anxiety or other mental health conditions. This can be from dealing with seizures or from the side effects of antiseizure medicines.
  • Sudden, unexpected death. Rarely, a single seizure causes death. This is called sudden unexpected death in epilepsy (SUDEP). Seizures that aren't managed well and other factors play a role in the risk of SUDEP. But experts don't know the overall risks or the cause. Good treatment of seizures is vital in preventing SUDEP.

Prevention

People who have more than one seizure should stay away from things that can cause a seizure, such as:

  • Not sleeping enough.
  • Using alcohol or illicit drugs.
  • Stress.
  • Being around flashing lights.
By Mayo Clinic Staff