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Generalized Seizure

Written by Ada’s Medical Knowledge Team

Updated on

What is a generalized seizure?

A generalized seizure occurs when there is a disturbance to electrical activity on both sides of the brain, potentially resulting in a loss of bodily control and, usually, consciousness. There are several different types of generalized seizure, all with varying symptoms. 1

Seizures tend to last only a few seconds or minutes. If a seizure lasts longer than this, it is important to seek immediate medical attention. 2 The affected person will typically be able to return to normal after it has taken place, but complications can arise, such as injury from collapsing or an inability to regain consciousness. The tendency to have repeated seizures is known as epilepsy, a condition which affects around 1 in 100 people in the US. 3 However, a single seizure does not mean the affected person is epileptic.

Epilepsy with generalized seizures is mostly idiopathic, meaning there is no definitive cause. People with a family history of the condition, however, are more likely to be diagnosed. In most cases, generalized seizures will begin during childhood or adolescence. 2 Sometimes, however, epilepsy can be triggered by another condition, such as brain trauma or a Stroke.

There is no cure for epilepsy, but seizures may stop or reduce as a person gets older. The majority of those affected by epilepsy can control the condition through medication. 4

Generalized seizure symptoms

A person affected by epilepsy with generalized seizures may experience one or more of several different types of possible seizure.

Early signs of a seizure - Aura

There are certain signs and symptoms that can indicate that a seizure is about to occur. These signs and symptoms typically manifest in advance of the specific symptoms of a seizure and are collectively known as an aura. However, auras do not always occur in those affected by epilepsy, and some with the condition may never experience one. An aura can be identified by the following: 4 5

  • Unusual movements
  • Intense emotions
  • Numbness
  • Dread or anxiety
  • Pain

Tonic-clonic seizures

Tonic-clonic seizures are the most common type of generalized seizure. 1 Historically, they have also been known as grand-mal seizures. A generalized tonic-clonic seizure begins with what is known as the tonic phase, during which the following symptoms typically occur: 4 6

  • All muscles stiffen
  • The affected person generally falls and loses consciousness
  • Air is forced out of the lungs, often causing a groan
  • The jaw contracts
  • Saliva may escape from the mouth
  • The affected person may bite their cheek or tongue

This is followed by the clonic phase, during which the affected person’s limbs begin to rapidly jerk about. These shaking movements should stop after a few minutes. It may take some time to recover consciousness after this phase. The following may also occur during a tonic-clonic seizure: 4 6

  • The face may turn a blue color due to difficulty breathing
  • Loss of bowel control
  • Confusion and irritability after waking up
  • Muscle pain from the contractions

Absence seizures

Absence seizures, otherwise known as petit-mal seizures, are characterized by the affected person’s tendency to stare into space, often without anyone noticing. As a result, the condition is often confused with daydreaming. Absence seizures are more likely to be experienced by children, with adults rarely affected. An absence seizure usually lasts for around 10 seconds and can be identified by the following symptoms: 7 8

  • A sudden loss of consciousness with no fall
  • The eyes staring blankly into space
  • All activity ceasing
  • The eyelids fluttering

Read more about Childhood Absence Epilepsy »

A less common seizure with very similar effects also exists; this is called an atypical absence seizure. In this type, the loss of awareness can be more gradual than in a typical absence seizure, but the effects typically last for a longer period of time. Changes in muscle activity can occur in both typical and atypical absence seizures, but they are often more noticeable during an atypical seizure. These changes can include: 8 9

  • Mouth movements, such as chewing or lip smacking
  • Hand movements, such as the rubbing of the fingers
  • Repeated blinking
  • Slumping or falling down

Tonic seizures

During a tonic seizure, the affected person’s muscle tone increases greatly, leading the body to tense up and become stiff. The affected person may fall over if they are standing when the seizure starts. Unlike a tonic-clonic seizure, a tonic seizure does not always lead to loss of consciousness or awareness. A tonic seizure usually lasts for fewer than 20 seconds. 10

Atonic seizures

Also known as a drop attack, an atonic seizure causes a rapid decrease in muscle strength. This can lead to the affected person falling to the floor, though consciousness is usually retained. 11

Myoclonic seizures

Myoclonic seizures occur when the body jerks for a very short period, usually less than a second. Any part of the body can be affected, but the arms are the most common location. The effects of a myoclonic seizure are often minimal, but can sometimes cause the affected person to drop or throw an object they are holding. 1

Clonic seizures

Clonic seizures are a rare type of seizure, most common in infant children. 12 During a clonic seizure, the affected person’s body jerks around repeatedly as a result of the body’s muscles rapidly contracting and relaxing. This occurs without the tonic or stiffening phase observable in a tonic-clonic seizure. Symptoms usually last for under a minute.

Focal/partial seizures vs generalized seizures

Focal or partial seizures start in one side of the brain. At first, they will only affect the parts of the body that the affected part of the brain controls. A simple focal seizure may cause unusual physical feelings or force involuntary movements in one limb. A complex focal seizure will impair the affected person’s awareness and can bring on a temporary loss of consciousness. Sometimes focal seizures can spread to the other side of the brain and turn into a generalized seizure, which is then called a secondary generalized seizure. 13

Causes of generalized seizures

When the flow of electrical signals in the brain gets disrupted, the abnormal activity may cause a seizure. The exact cause of an electrical disturbance behind a seizure is often unknown. As many as 1 in 10 people will have a seizure in their lifetime and many will never experience one again. 14 Others will experience them as part of a secondary condition that counts generalized seizures as a symptom.

Idiopathic epilepsy

Idiopathic epilepsy means that there is no clear cause for the neurological disorder, though hereditary factors may play a role in some cases. 14 60 percent of people with epilepsy have idiopathic epilepsy, making it the most common form of the disorder. The majority of those affected by idiopathic epilepsy will not be diagnosed with any other brain condition. ref1

Symptomatic epilepsy

When the cause of epilepsy is identifiable, such as historic brain trauma or a diagnosed brain condition, then it is known as symptomatic epilepsy or secondary epilepsy, because it is not the primary cause of the condition.

Causes of symptomatic epilepsy include: 1 14

  • Historic brain trauma
  • An abnormally formed brain
  • Brain infections such as encephalitis, neurocysticercosis or meningitis
  • Low birth weight or lack of oxygen while in the womb
  • Cerebral palsy
  • Brain tumors or growths
  • Strokes that restrict oxygen to the brain

Provoked first-time seizure

If a generalized seizure has an identifiable cause, but is unlikely to recur in the absence of that cause, then it is not judged to be epileptic. Some of the causes of this type of generalized seizure can include: 15 16

  • Alcohol withdrawal
  • Pre or post-pregnancy eclampsia
  • Low or very high blood sugar
  • Disturbances in blood salt levels
  • Lack of sleep
  • Stress or anxiety
  • Hunger

Generalized seizure triggers

There are some triggers that can make seizures more likely in those affected by epilepsy, as well as those who have never had a seizure before, but who are susceptible. These include: 1 16

  • Stress or anxiety
  • Lack of sleep
  • Quickly flashing or strobe lighting
  • Recreational drug use
  • Some prescription medications, including antidepressants
  • Drinking large amounts of alcohol
  • Low or very high blood sugar levels
  • Menstruation
  • Exposure to lead, carbon monoxide or other toxins

Generalized seizure diagnosis

If a person is affected by symptoms consistent with a seizure, then it is recommended that they visit a medical professional. To determine whether the affected person is epileptic, questions will be asked about the symptoms being experienced, and several tests may be run to see if a cause can be determined. The medical professional may ask whether the affected person has a family history of epilepsy or any of the conditions that make epilepsy more likely.

Several tests can be run to check whether a person may be epileptic. However, no one test is able to determine for sure that a diagnosis of epilepsy should be made. A doctor will typically be unable to confirm a diagnosis of epilepsy until at least a second seizure has taken place. What appears to be a generalized seizure may sometimes be down to another, non-epileptic condition, such as a panic attack or tourette's syndrome. 16


An electroencephalograph (EEG) measures the electrical signals passing through the brain to see if there are any abnormalities. To perform the test, a number of electrode patches are attached to the affected person’s scalp, with the test taking around 20 to 30 minutes. If the test shows a positive result for abnormal activity, this may suggest a certain type of epilepsy, which can help a medical professional in making their diagnosis. 16

Someone who has experienced a seizure may show no abnormal brain activity in an EEG. This may be because the abnormal activity may only show up while the seizure is taking place, or it takes place in a part of the brain that the EEG does not reach. Unusual brain activity can also be recorded, even if the affected person does not have epilepsy. 17 This is why it is useful for an EEG test to take place within 24 hours of the suspected seizure. EEG tests are also more likely to be accurate if they take place when the affected person is tired or drowsy. 16

Brain scans

Several brain scans may be used to help with diagnosis following a generalized seizure. Some of the most common of these are: 3 16

  • Magnetic resonance imaging (MRI) scans
  • Computed tomography (CT) scans
  • Positron emission tomography (PET) scans

MRI scans and CT scans analyse the structure of the brain to allow doctors to see if there are any abnormalities, such as tumors, that might be causing the seizure. PET scans look at how certain areas of the brain are functioning and can offer clues as to where the seizure originated from.

Blood tests

Some of the conditions that are associated with symptomatic epilepsy and seizures are detectable through blood tests. Blood tests are able to measure: 3 16

  • Blood sugar levels
  • Organ function
  • The presence of an infection
  • Blood pressure
  • The presence of a blood condition, such as anemia

Read more about Blood Test Results »

Nonepileptic seizures

There are various conditions that may resemble a general seizure but are caused by factors other than electrical activity in the brain. These are known as non-epileptic events or non-epileptic seizures. Some conditions that may be mistaken for generalized seizures include: 1 16 18

  • Panic attacks
  • Fainting
  • Collapsing due to irregular heart beats (cardiac arrhythmia)
  • Collapsing due to other heart conditions
  • Tourette syndrome tics and involuntary movements
  • Children holding their breath for extended periods
  • Psychogenic non-epileptic seizures, which are seizures caused by psychological reasons, e.g., high emotions or stress

Generalized seizure treatment

Treatment for generalized seizures depends on the diagnosis that has been made. If the affected person has epilepsy, then in most situations medication can be used to control their condition. However, if the seizure has only occurred once, then it is unlikely that medication will be prescribed at that stage. 16 ref1 Following two to five years of seizure-free treatment with medication, 70 percent of children and 60 percent of adults with epilepsy can have their drugs withdrawn with no subsequent relapse of symptoms. 14

Anti-seizure medications

Many different types of medication are used to control seizures. Only 20 percent of those affected by epilepsy do not have their seizures halted or dramatically reduced by anti-seizure medication. 1 Some of the prescribing considerations, which a medical professional may make in recommending which type to use, include: ref1 16

  • Type of seizure
  • How regular the seizures are
  • Age of the affected person
  • Lifestyle of the affected person, including diet
  • Other medications used
  • Whether the affected person is pregnant or attempting pregnancy

Usually, just one type of anti-seizure medication is required, rather than a combination. All medications have benefits and side effects. The side effects are usually minor and will be outlined by the doctor. However, if there is a serious impact on the affected person, then regulating the dose or switching to a new type of medication might be recommended. A doctor should be informed if a person affected by epilepsy is pregnant or attempting to become pregnant while on anti-seizure medication.

Some anti-seizure medications will impact the effectiveness of other drugs taken at the same time, including the oral contraceptive pill. 1

In certain cases, doctors may recommend stopping the use of anti-seizure medication, for example, if a number of years have passed since a seizure has taken place. However, stopping the use of medication is dangerous if done without first consulting a healthcare professional and may lead to the return of seizures. 16

Ketogenic diet

A high-fat, low-carbohydrate, low-protein ketogenic diet is sometimes recommended as a treatment for epilepsy. It can be useful for children affected by forms of epilepsy that are resistant to anti-seizure medication. The ketogenic diet forces the body to use fat, rather than glucose, as its primary energy source. 19 This diet has been shown to reduce the number of seizures experienced by people affected by several different types of epilepsy. However, it is a difficult diet to maintain and may lead to health issues if incorrectly followed, so the advice of a dietician is recommended.


Very rarely, a person affected by generalized seizures may be recommended for surgery. Mostly, surgical treatment is recommended for those with focal seizures that start in a small, identifiable part of the brain. One example of where surgery could be appropriate is for children affected by focal seizures that regularly spread and become generalized seizures.

Brain surgery, like all surgery, has risks including damage to the brain that could cause physical or mental impairment. However, if medications stop working then it may be the most effective way for an affected person to halt their seizures. 16

Vagus nerve stimulation

A vagus nerve stimulator is an electronic device which is implanted underneath the affected person’s skin and attached to the vagus nerve near to the left collarbone. The stimulator sends electrical energy to the brain through the nerve, which can lessen the impact of a seizure or reduce the likelihood of one taking place. 1 The vagus nerve stimulator is not usually a replacement for medication, but is often used alongside it.

Another method that makes use of electronic signals to moderate the effects of epilepsy is called responsive stimulation. This uses a device to monitor brain activity and respond with electronic stimulation if it detects a seizure is about to take place. 16

Generalized seizure prevention

Idiopathic epilepsy can not be prevented. However, the following may help prevent epilepsy caused by external factors: 14 16

  • Taking steps to avoid head trauma, such as wearing seatbelts in cars or helmets while cycling
  • Preventing a lack of oxygen supply to the brain through such measures as effective medical treatment before and after childbirth
  • Preventing infections through receiving appropriate vaccinations, for example
  • Avoiding high blood-pressure or heart disease through the maintenance of a nutritionally balanced diet and regular exercise

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Generalized seizure complications

Given the success rates of anti-seizure medication, the effects of epilepsy can be minimal for many affected by the condition. However, there are several complications that can arise for those experiencing general seizures, either regularly or intermittently.

Depression and anxiety

Because generalized seizures can happen at any time, they can have a considerable impact on the affected person’s wellbeing. The rate of depression and anxiety among those affected by epilepsy is considerably higher than among the general population. 20 21

Accidental injury

Given the loss of bodily control and consciousness that can occur during a generalized seizure, there are added dangers for those affected by epilepsy. If seizures are a regular occurrence, then any activity where a sudden loss of concentration would cause a precarious situation, such as swimming or weight lifting, might be a risk.

Falling to the floor suddenly and the rapid muscle contraction that follows also carries the risk of injury to the body. There may be steps the affected person can take to create a safe environment at home such as covering sharp edges and installing smoke detectors. 22

Employers in the U.S. generally do not have the right to deny employment to a person affected by epilepsy for safety reasons if reasonable adjustments can be made to ensure that the affected person poses no significant danger to themselves or others. 23

Driving after a seizure

In most U.S. states, a person affected by regular seizures will need to produce a document showing they have been seizure-free for a certain period of time in order to be eligible for a driving license. The time period varies by state, but it is usually between a few months and a year. 24

Status epilepticus

If a seizure lasts for over five minutes, or repeated seizures occur without the affected person regaining consciousness, then this is called status epilepticus. This is a life-threatening condition, and medical treatment should be sought immediately. 18

Sudden unexplained death in epilepsy (SUDEP)

One in every 1,000 people with epilepsy die suddenly for reasons that are poorly understood by medical professionals. The risk is higher for those who are experiencing regular seizures. The risk of SUDEP may be lowered if anti-seizure medication is taken at the prescribed levels. 16


Q: What should I do if I see someone having a seizure
A: If you see someone having a seizure, and they are not in a dangerous location, such as on a busy street, do not attempt to:

  • Restrict them
  • Move them
  • Stop them moving

The following are actions that can be taken to help:

  • Put a soft object underneath the person’s head if they have fallen to the floor
  • Make sure that any tight clothing around their neck, for example a tie, is loosened
  • When any jerking movements have stopped, lay them on their side to make sure they do not choke on their own vomit

Take note of the time the seizure starts and ends. If any of the following occurs, then contact emergency medical services:

  • The seizure lasts for more than five minutes
  • The person does not regain consciousness
  • Another seizure begins before they have regained consciousness