Tonic and Clonic Seizures: Symptoms, Causes, Treatment

A comprehensive guide to understanding, identifying, and treating tonic and clonic seizures, including what to do during an episode and prevention.

By Medha deb

Created on Oct 3, 2025

A comprehensive guide to understanding, identifying, and treating tonic and clonic seizures, including what to do during an episode and prevention.

Tonic and Clonic Seizures: Symptoms, Causes, Emergency Actions, and Treatments

Tonic and clonic seizures are among the most recognized types of epileptic seizures, often referred to as “grand mal seizures.” This guide explores the characteristics, causes, diagnosis, first aid, and management strategies for tonic and clonic seizures, providing essential information for patients, caregivers, and the general public.

What Are Tonic and Clonic Seizures?

Tonic and clonic seizures are two distinct phases that can occur together or separately during generalized seizures that affect both sides of the brain. When both phases occur in a single seizure, this is known as a tonic-clonic seizure (formerly referred to as a grand mal seizure) .

Tonic phase: Characterized by muscle stiffening, leading to sudden falls or unconsciousness.
Clonic phase: Consists of rhythmic, jerking movements of the limbs and face, often following the tonic phase.

Patients may lose awareness or experience impaired consciousness during these seizures. Tonic and clonic phases may also occur as isolated events:

Tonic-only seizures: Only the stiffening phase occurs; seen in some forms of epilepsy.
Clonic-only seizures: Only the jerking phase occurs; less common and can be harder to diagnose.

Understanding the Phases: Tonic vs. Clonic

Phase	Features	Duration
Tonic phase	Muscles suddenly stiffen; loss of consciousness; may fall down; possible vocalization or cry	10-20 seconds
Clonic phase	Rhythmic twitching and jerking; possible incontinence; possible tongue bite	1-2 minutes (often less)

Not all tonic-clonic seizures follow the same pattern; some may have a brief tonic or clonic phase only. After the seizure, a period of confusion or deep sleep (postictal state) is common .

Signs and Symptoms of Tonic-Clonic Seizures

Symptoms vary depending on the stage of the seizure and individual differences, but the following are typical:

Sudden loss of consciousness
Sudden rigidity and falling (tonic phase)
Crying out or vocalization as air is forced past the vocal cords
Rhythmic, jerking movements of arms and legs (clonic phase)
Possible incontinence (loss of bladder or bowel control)
Tongue or cheek biting
Foaming at the mouth or drooling
Cyanosis (bluish skin color) if breathing is briefly impaired
Followed by confusion, drowsiness, headache, or deep sleep (postictal state)

Some patients may experience an aura prior to the seizure, such as unusual sensations, visual or sensory changes, or a sudden unexplained feeling. The aura can sometimes serve as a warning, especially if the seizure originates as a focal onset before becoming generalized .

Causes and Risk Factors

Tonic and clonic seizures can occur due to a variety of neurological and systemic factors. While epilepsy is the most common underlying condition, other reversible or acute factors may also trigger seizures:

Epilepsy (genetic or structural): Primary risk factor for recurring seizures
Brain injury or trauma
Brain tumors or lesions
Stroke or other vascular injury
Metabolic disturbances: Hypoglycemia (low blood sugar), electrolyte imbalances, kidney or liver failure
High fever (febrile seizures): More common in infants and young children
Infections: Meningitis, encephalitis, or other central nervous system infections
Alcohol or drug withdrawal
Genetic predispositions (family history of seizures or epilepsy)

In about 50% of cases, the specific cause remains unknown, and the disorder may be described as “idiopathic.” Seizures can be provoked by acute illness in individuals without epilepsy .

Diagnosis: How Are Tonic and Clonic Seizures Identified?

Diagnosis typically involves:

Detailed medical history: Including witness descriptions of events
Physical and neurological examination
Electroencephalogram (EEG): Measures electrical activity in the brain to detect abnormal patterns
Brain imaging: MRI or CT scan to check for structural brain changes
Blood tests: To rule out metabolic or infectious causes
Other tests as needed, such as toxicology screens for drugs or alcohol

A precise description of the event—including the duration, movements, behavior, progress, and recovery—is essential for accurate diagnosis. Video recordings (when safely possible) can assist clinicians in differentiating seizure types from other possible conditions, such as non-epileptic events.

How to Respond During a Tonic-Clonic Seizure: First Aid Steps

Immediate action can help ensure the safety and recovery of a person experiencing a tonic or clonic seizure. Never try to restrain the person or put anything in their mouth.

Stay calm and note the time the seizure starts.
Clear the area of any sharp or hazardous objects.
Guide the person to the floor to prevent injury, if possible and safe.
Turn the person gently onto their side (recovery position) as soon as possible to help keep the airway clear and reduce the risk of choking on saliva or vomit.
Cushion the person’s head with a soft item (like a folded jacket) to prevent head injury.
Loosen tight neckwear to aid breathing.
Move objects away but do not move the individual unless they are in immediate danger (e.g., near water, on stairs).
Do not restrain movements, hold down their arms or legs, or place anything in their mouth—these actions can cause injury.
Do not give food, drink, or medication by mouth until the person is fully alert and aware.
Stay with the person until they have recovered; provide reassurance as they become aware, as confusion is common.

When to Call Emergency Medical Help

The seizure lasts longer than 5 minutes.
Another seizure follows immediately without regaining consciousness.
The person has trouble breathing, does not resume normal breathing after the seizure, or fails to regain consciousness.
They are injured, pregnant, or have other underlying health conditions (such as diabetes).
The seizure happens in water, or there are injuries from the fall.
This is the person’s first seizure, or you are unsure of their history.

Treatment Options for Tonic and Clonic Seizures

Individualized treatment is crucial. Treatment depends on the underlying cause, seizure frequency, and the patient’s health profile. Options include:

Medications: Antiseizure (antiepileptic) drugs are the mainstay for ongoing seizure management. Common options: valproic acid, levetiracetam, lamotrigine, phenytoin, topiramate, and carbamazepine.
Addressing underlying causes: Correcting metabolic disturbances, treating infections, or discontinuing triggering substances.
Ketogenic diet: A high-fat, low-carbohydrate diet shown to reduce seizure frequency in some patients, particularly children with refractory epilepsy.
Epilepsy surgery: Considered for select cases of focal epilepsy not responsive to medication; generally not indicated for generalized tonic-clonic seizures.
Vagus nerve stimulation (VNS) and other neuromodulation devices: For patients who do not achieve adequate seizure control with medication alone.

Medication selection is based on seizure type, side effect profile, patient age, co-existing conditions, and, for women, reproductive considerations. Close follow-up and medication adjustments can help minimize side effects and maximize seizure control.

What is Status Epilepticus?

Status epilepticus is a life-threatening emergency in which a seizure lasts more than five minutes, or repeated seizures occur without recovery between them. Hospital treatment with intravenous medication (such as benzodiazepines and other antiepileptics) is essential. Status epilepticus requires prompt, aggressive management to prevent brain injury and systemic complications .

Living with Tonic-Clonic Seizures: Precautions and Lifestyle Measures

Medication adherence: Take prescribed medications at the same time daily.
Consistent sleep: Maintain a regular sleep schedule, as sleep deprivation can trigger seizures.
Avoid alcohol and recreational drugs: These substances may lower the seizure threshold or interact with medication.
Manage stress: Stress and emotional disturbances can precipitate attacks in some people.
Consider safety in daily life: Swimming, bathing, climbing, and operating heavy machinery should be undertaken with caution and appropriate supervision.
Identify triggers: Some individuals can identify personal seizure triggers, such as flashing lights, missed medications, or illness—and learn to avoid them when possible.

Prognosis and Outlook

The outlook for people experiencing tonic and clonic seizures depends on the underlying cause and response to treatment. Many individuals achieve good seizure control with medication. Some may experience isolated seizures without recurrence. If seizures remain uncontrolled or are frequent, further evaluation and advanced management strategies may be needed. Early diagnosis, tailored therapy, and adherence to safety strategies are key to improving quality of life and reducing long-term risks.

Frequently Asked Questions (FAQs)

What is a tonic-clonic seizure?

A tonic-clonic seizure (formerly “grand mal”) is a type of generalized seizure characterized by a sudden loss of consciousness, muscle stiffening (tonic phase), and rhythmic jerking (clonic phase) of the limbs and body.

What should bystanders do during a tonic-clonic seizure?

Help the person to the ground, clear the area of objects, turn them gently on their side, cushion their head, and stay with them until they regain full consciousness. Do not insert anything in their mouth or restrain their movements. Call emergency services if the seizure lasts more than five minutes or if there are injuries or complications.

What causes tonic and clonic seizures?

They are most commonly caused by epilepsy (with or without a genetic or structural basis), but can also result from fever (in children), infections, metabolic imbalance, head injury, or sudden withdrawal from alcohol or certain medications.

Can tonic-clonic seizures be prevented?

Prevention mainly involves adhering to prescribed treatment, managing triggers, getting enough sleep, avoiding alcohol or recreational drugs, and closely following your healthcare provider’s recommendations.

Is epilepsy curable?

Epilepsy is generally a chronic condition requiring long-term management, but some people achieve complete seizure freedom with medication or lifestyle changes. Rarely, curative surgery is possible for selected patients with focal epilepsy causes. Most cases of generalized tonic-clonic seizures are managed but not cured.

When should someone seek emergency help for a seizure?

Call emergency services if a seizure lasts longer than 5 minutes, is followed by another seizure without recovery, the person is injured, pregnant, or does not resume normal breathing or consciousness, or if it is their first seizure.

Additional Resources

Epilepsy Foundation: Education and support for those living with seizures.
National Institute of Neurological Disorders and Stroke (NINDS): Information and research updates on epilepsy and seizures.
Consult a certified neurologist or epilepsy specialist for personalized diagnosis and treatment.

Note: This article is for informational purposes only and should not replace professional medical advice or emergency care. If you or someone you know experiences a seizure for the first time or under concerning circumstances, seek prompt medical evaluation.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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