An Overview of Tonic-Clonic Seizures

Formerly called "grand mal" seizures

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A tonic-clonic seizure, formerly called a grand mal seizure, is the "classic" type of seizure most people are familiar with. It involves loss of consciousness or awareness, plus uncontrolled jerking and stiffness of the arms, legs, or body. It generally lasts just a few seconds to a couple of minutes.


Symptoms of tonic-clonic seizures can include any combination of the following:

  • An unusual sensation prior to the seizure that's often described as an aura
  • Jerking and stiffening of one or more limbs
  • Drooling
  • Urinary or fecal incontinence
  • Tongue biting
  • Falling down
  • Screams, grunts, or sounds
  • Eye movements or eye jerking
  • Confusion or sleepiness afterward; inability to recall the event

Due to impaired consciousness, you may not be aware that you're having such a seizure.

A tonic-clonic seizure can be classified as either a primary or secondary generalized seizure.

Secondary Generalized Tonic-Clonic Seizure
  • Starts in one part of the brain, but spreads to both sides

  • Awareness or partial awareness are possible at the seizure onset

  • Impacts area(s) of body controlled by that brain region

Primary Generalized Tonic-Clonic Seizure
  • Involves the whole brain

  • Complete lack of awareness and memory

  • Impacts the whole body

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When the brain is injured, the electrical activity that normally controls brain function may become disturbed or erratic. One or more part of the brain may then 'misfire,' causing unwanted physical actions that often manifest as a tonic-clonic seizure.

A number of medical problems can cause a person to experience tonic-clonic seizures, including:

  • Epilepsy: This is the most common cause. You can be born with it or develop it later in life due to brain damage.
  • Brain injury: Head trauma, brain injury, strokes, aneurysms, brain tumors, and brain infections may cause long-term epilepsy.
  • Severe illnesses/infections and high fevers: Seizures should improve once these issues resolve.
  • Certain medications
  • Drug or alcohol overdose or withdrawal, due to disturbances in brain activity
  • Electrolyte abnormalities
  • Organ failure


A tonic-clonic seizure is often diagnosed based on the clinical manifestations. Diagnostic testing such as electroencephalogram (EEG) and brain imaging may also help in diagnosis and the creation of a treatment plan.

Seizure diagnosis is based on:

  • Description: If you have had a primary generalized tonic-clonic seizure, you will probably not recall the event. However, if you experienced a secondary generalized tonic-clonic seizure, you may recall how you felt immediately prior to the seizure. If anyone else was around, their description of the event is helpful.
  • EEG: An EEG is a test that detects brain waves. If you've had a seizure or are prone to seizures, your EEG may show one or more areas or of erratic electrical brain activity. An EEG is particularly helpful if you have a seizure during the test that correlates with the electrical abnormality.
  • Sleep-deprived EEG: Sometimes, an EEG does not show electrical abnormalities when you are well rested but will show them when you're sleep-deprived.
  • Brain imaging: Brain computed tomography (CT) and magnetic resonance imaging (MRI) scans do not show seizures, but can identify abnormalities that can cause tonic-clonic seizures, such as a brain tumor, stroke, abscess, or abnormal blood vessel in the brain.

Treatment and Prevention

Tonic-clonic seizure treatment is primarily focused on prevention, however, in some situations such as with prolonged seizures, treatment will be needed acutely.

A seizure that lasts five minutes or longer is a potentially life-threatening emergency called status epilepticus. It typically requires treatment with a fast-acting medication that stops the seizure right away.

Medications used to treat status epilepticus include intravenous forms of lorazepam, diazepam, and midazolam.

Avoiding Triggers

There are a variety of ways to effectively prevent seizures. Controlling the use of triggers such as alcohol, drugs, and medications is by far the safest way to prevent a seizure.


Most people who are prone to recurrent tonic-clonic seizures can experience a seizure due to a fever, infection, sleepiness, or no known trigger at all. Anti-seizure medications, which are also referred to as anticonvulsants, are often recommended to prevent or reduce recurrent seizures.

Common anti-seizure medications used for treating tonic-clonic seizures include:

  • Keppra (levetiracetam) *
  • Depakote (valproic acid) *
  • Lamictal (lamotrigine)*
  • Topamax (topiramate) *
  • Zonegran, Zonisade (zonisamide) *
  • Fycompa (perampanel) *
  • Tegretol, Carbatrol (carbamazepine)
  • Dilantin (phenytoin)
  • Neurontin (gabapentin)
  • Phenobarbital
  • Gabitril (tiagabine)

*Preferred anticonvulsants for primary generalized tonic-clonic seizures

A Word From Verywell

There is a high likelihood that you will reduce the number of tonic-clonic seizures you have once doctors find the cause and get you on anticonvulsant medication. Most people with epilepsy can prevent seizures and have a good quality of life. That said, tonic-clonic seizures can pose some social and emotional challenges. Learning to explain your illness to the people in your life can help prevent fear and misunderstandings and provide you with support you need.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Gursahani R, Gupta N. The adolescent or adult with generalized tonic-clonic seizures. Ann Indian Acad Neurol. 2012;15(2):81-8. doi:10.4103/0972-2327.94988

  2. Dobesberger J, Ristić AJ, Walser G, et al. Duration of focal complex, secondarily generalized tonic-clonic, and primarily generalized tonic-clonic seizures--A video-EEG analysis. Epilepsy Behav. 2015;49:111-7. doi:10.1016/j.yebeh.2015.03.023

  3. Rheims S, Ryvlin P. Pharmacotherapy for tonic-clonic seizures. Expert Opin Pharmacother. 2014;15(10):1417-26. doi:10.1517/14656566.2014.915029

Additional Reading

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.