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Tonic-Clonic Seizure

A seizure is a abrupt and temporary change in the electrical and chemical activity in the brain which causes a change a person’s movement, behaviour, level of awareness, and/or feelings. Some people will experience a seizure, but will not go on to be diagnosed with epilepsy, where others will.

What Is A Tonic-Clonic Seizure?

This type of epileptic seizure (sometimes called a convulsion) is what the majority of people think of when they hear the word “seizure”. Its also sometimes known as a “grand mal Seizure.” They combine the features of tonic and clonic seizures. Tonic means stiffening, and clonic means rhythmical jerking.

  • The tonic phase comes first.
    • The person loses consciousness and will fall to the floor.
    • A person might bite their tongue or their cheek. If this happens, there may be blood around the mouth.
    • All the muscles stiffen.
    • Air being forced past the vocal cords causes a cry or groan.
  • After the tonic stage comes the clonic phase.
    • The arms and usually the legs begin to jerk rapidly and rhythmically, bending and relaxing at the elbows, hips, and knees.
    • After a few minutes, the jerking slows and stops.
  • The person’s face may look grey or a bit blue if they are having trouble breathing or the seizure last for a period of time.
  • They may lose control of their bladder or bowel as the body relaxes.
  • Consciousness or awareness, returns slowly.
  • These seizures generally last 1 to 3 minutes. Afterwards, the person may be sleepy, confused, irritable, or depressed.
  • A tonic-clonic seizure that lasts longer than 5 minutes needs immediate medical help. Call 111 for help
  • A seizure that lasts more than 5 minutes, or three seizures in a row without the person coming to between them, is a dangerous condition. This is called status epilepticus; and requires prompt medical attention. The longer a seizure lasts, the less likely it will resolve of its own accord

Very long seizures are dangerous, and can increase the chance of long term damage or death. This makes it very important to identify and treat status epilepticus as promptly as possible. 

Which Part Of The Brain Does a Tonic-Clonic Seizure Come From?

Tonic-clonic seizures can start with one or both sides of the brain.

Who May Be At Risk For Tonic-Clonic Seizure?

This type of seizure can affect children and adults.

  • When tonic-clonic seizure happens with a child, some children will grow out of their epilepsy condition. Others who are seizure-free for a year or two while taking prescribed seizure medication may be able to come off medicine slowly. Decisions about coming off medicine must be done with advice from a doctor.
  • The risk that a person will have more seizures depends a number of things such as whether epilepsy waves or patterns are seen on the EEG (electroencephalogram) or whether the neurological exam is normal.

According to the US Epilepsy Foundation

    • Children who have had tonic-clonic seizures and have a normal EEG and neurological exam have a 70% chance of being seizure-free without medication.
    • If a child who has had tonic-clonic seizures has epilepsy waves on the EEG or an abnormal exam, the chance of being seizure-free off medicine is only 30%.
    • Children who have generalized onset tonic-clonic seizures are more likely to come off seizure medicine and do well than are children with tonic-clonic seizures that begin in one side of the brain (focal to bilateral).
  • Some people have types of epilepsy that include tonic-clonic seizures and other seizure types. For example, a person could also have other forms of generalized seizures (such as absence, atonic, clonic, myoclonic, or tonic) or focal onset seizures.
  • Talk to your Doctor about the different seizure types, including first aid and what to expect.

What Is It Like To Have A Tonic-Clonic Seizure?

When people have tonic-clonic seizures, they are generally not aware of what’s happening.

First aid should be focused on making sure the person is breathing freely and they don’t hurt themselves.

When the seizure ends, the person may be sleepy or confused for a few minutes, an hour, or even more.

They may lose bladder or bowel control during or after the seizure and need to go to the bathroom.

Sometimes, people bite their tongue or inside of the cheek during a seizure and their muscles may feel sore and could be bleeding.

If any injury has happened or the seizure lasts 5 minutes or more, call for medical help.


What should you do if someone is having a tonic-clonic seizure?

If you see someone having a tonic-clonic seizure, take the actions below:

  • Make sure there’s nothing in their mouth and that their airway isn’t obstructed.
  • Clear the area around them so there are no sharp or hard objects nearby.
  • Place something soft, such as a pillow, under their head.
  • Gently position them on their side.
  • Loosen any restrictive clothing or accessories, such as a belt.
  • Remove their eyeglasses.
  • Time the seizure or seizures.

What Should I Do If I Think My Child, Loved One, Or Myself May Have Tonic-Clonic Seizures?

If you think your child, loved one, or yourself may be having tonic-clonic seizures, please talk to the doctor soon as possible. Tonic-clonic seizures can lead to injury and in some rare cases death. Getting these diagnosed and treated quickly is essential.