A tonic-clonic seizure makes a person’s whole body twitch and jerk, then it causes them to become unconscious. “Grand mal” is an older term for this type of seizure. These seizures can be dangerous, as they have the potential to cause injuries.

Tonic-clonic seizures can occur as a result of epilepsy, a brain condition, certain medications, some infections, and several other health conditions.

During a tonic-clonic seizure, a person’s arms and legs become rigid and stiff, and large muscle groups slowly jerk uncontrollably.

This article will discuss the symptoms, causes, diagnosis, and treatments associated with tonic-clonic seizures. It will also look at the risk factors, any possible lasting effects, and how to help someone who is having a seizure.

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The symptoms of tonic-clonic seizures usually follow one another. They include:

  • aura, such as a change in mood, strange tastes or smells, or a headache
  • stiffening muscles
  • blue skin or lips
  • jerky movements in large muscle groups
  • foaming at the mouth or biting the tongue
  • loss of bowel or bladder control

Tonic-clonic seizures can last from a few seconds to a few minutes.

Once a person’s body stops jerking, they will enter a postictal state. This means that although they are no longer unconscious, they are not yet fully aware of their surroundings. During this time, the person may experience sleepiness, confusion, and agitation. This can last for a few minutes or several hours.

A seizure is the result of an imbalance of the excitation and inhibition parts of the brain. This imbalance can result from genetic or environmental factors.

Some genetic factors include:

  • abnormal neuronal connections when the top layer of the brain does not form correctly
  • abnormal gamma-aminobutyric acid receptors that cannot monitor neuron activities properly
  • potassium channel mutations

People can also start having tonic-clonic seizures due to head trauma or febrile seizures, which occur when the body’s temperature is very high.

A doctor may diagnose epilepsy if the person has the following medical history:

  • they have had at least two seizures
  • the seizures were at least 24 hours apart
  • there is no evidence to suggest that other factors caused the seizures

The doctor will likely order a blood test and several other tests to confirm.

An electroencephalogram (EEG) test measures the electrical activity of the brain. People who have epilepsy tend to have certain EEG patterns that mean that they are more likely to have seizures.

People may also need to undergo an MRI scan, which looks at changes in the brain that may cause seizures.

Most tonic-clonic seizures stop by themselves, and people do not usually need to take antiseizure medications. However, if a person needs emergency treatment, doctors will usually administer benzodiazepines intravenously or intranasally.

A person may require antiepileptic medications to reduce the risk of seizures happening again. This depends on several factors, including the number and frequency of seizures a person has, the likelihood that they will happen again, and whether a person’s body will be able to tolerate any side effects.

Some side effects of antiepileptic medications include:

  • liver damage
  • congenital anomalies, if a person takes them during pregnancy
  • pancreatitis
  • memory problems
  • unintentional weight loss
  • osteoporosis
  • balance problems
  • tremors

There are several risk factors for experiencing a seizure. These factors include:

  • a family history of epilepsy or seizures due to fever
  • stroke
  • head injuries that lead to seizures
  • a lack of oxygen to the brain
  • babies born too small for their age or who have seizures in their first month of life
  • brain tumors
  • brain infections, such as meningitis
  • use of drugs, such as cocaine
  • certain conditions, such as cerebral palsy and autism spectrum disorder

There is also evidence to suggest that not getting enough sleep and exposure to flashing lights, such as strobe lights in nightclubs, can trigger seizures in certain people.

Although people can develop epilepsy at any age, it is more common for people to develop it in childhood or over the age of 60 years.

Usually, a seizure does not cause any lasting damage to the brain.

However, having many seizures, or having seizures that are particularly severe, may cause a person to become more forgetful or find it difficult to concentrate.

People with epilepsy have an increased risk of developing depression. Around 30% of adults with epilepsy have depression, and 10% have bipolar disorder.

People are also at higher risk of anxiety. This may need medical treatment, often in the form of antidepressants or therapy.

People with epilepsy are also at a higher risk of:

It is possible to die from a tonic-clonic seizure. For example, some people may fatally injure themselves while having a seizure, or they may drown if they have a seizure in water.

It is also possible for someone to die from sudden unexpected death in epilepsy (SUDEP). According to the Centers for Disease Control and Prevention (CDC), this happens in about 1 in every 1,000 people with epilepsy every year.

Certain factors may contribute to SUDEP. For example, while having a seizure, a person may unintentionally pause their breathing. If they pause for too long between breaths, the oxygen in their blood may drop to a life threatening level.

It is also possible that a person’s airways may become obstructed during a seizure, leading to suffocation. A seizure may also cause cardiac arrest.

To reduce the risk of death from a tonic-clonic seizure, people should:

  • try to avoid seizure triggers
  • try to avoid drinking too much alcohol
  • try to get enough sleep
  • train other people in their household in seizure first aid
  • take their seizure medications as prescribed

Seizures do not usually require emergency medical attention, according to the CDC.

People should only call emergency services if the person:

  • has not had a seizure before
  • has difficulty breathing or waking up after the seizure
  • has a seizure that lasts for longer than 5 minutes
  • has another seizure soon after the first
  • is hurt during the seizure
  • has a seizure in water
  • is pregnant or has another health condition, such as diabetes or heart disease

If someone is having a tonic-clonic seizure, the people around them can do the following first aid steps to help:

  1. Gently help the person to the floor.
  2. Turn them gently onto one side to help them breathe.
  3. Make sure that the area around the person is clear of anything that may cause injury, such as broken glass.
  4. Place a folded jacket or blanket under the person’s head.
  5. Remove any eyeglasses and loosen any neckties or anything else around the neck.
  6. Time the seizure and call for emergency medical treatment if it lasts for longer than 5 minutes.

It is important to stay with someone who is having a seizure until the seizure ends and they are fully aware of their surroundings.

Do not put anything into the mouth of a person having a seizure. This may cause them to choke.

If it is safe to do so, check to see if the person has a medical bracelet or any other emergency information.

Once someone’s seizure ends, if they do not need any medical treatment, make sure that they have someone who can take them home.

People often have temporary forgetfulness, trouble with speech, or difficulty moving after a seizure.

It is also more common for people to fall and hurt themselves, or to bite their tongue, during a tonic-clonic seizure than during other types of seizure.

Having epilepsy does not significantly shorten a person’s life expectancy. However, if a person has another condition alongside epilepsy, such as heart disease, this may lower their life expectancy.

Epilepsy can lead to death in rare cases.

It is possible that a person may sustain a life threatening injury while having a seizure. Also, having a severe, long lasting seizure may prevent enough oxygen from reaching a person’s brain, possibly leading to death.

It is important for a person to see a doctor if they experience a seizure that results in an injury. They should also seek medical advice if they have more than one seizure within 24 hours.

A person should see a doctor after their first seizure. They will be able to diagnose any underlying conditions and prescribe treatment, if necessary.

It is important to seek immediate medical treatment if a person severely injures themselves, has a seizure in water, or has an underlying health condition.

Around 40% of people who have a tonic-clonic seizure go on to experience another one.

People are more likely to have more than one tonic-clonic seizure in the days after the first one. However, the risk decreases as time passes after the first tonic-clonic seizure.

People are up to 60% less likely to experience further tonic-clonic seizures if they treat their epilepsy with medication.

People may find tonic-clonic seizures scary to experience, but these seizures do not often require medical treatment.

Bystanders can follow some basic first aid tips to help someone who has a seizure.

People with epilepsy can also take antiepileptic medications. If a person treats their epilepsy, they are less likely to continue having tonic-clonic seizures.