May also be called: Grand Mal Seizure

A tonic-clonic seizure is a sudden attack that brings on intense muscle spasms and loss of consciousness. It is caused by abnormal electrical activity in the brain and affects the entire body.

More to Know

A tonic-clonic seizure can happen at any age. It's most commonly associated with epilepsy but can also be caused by low blood sugar, stroke, infections, traumatic head injuries, drug and alcohol withdrawal, and other underlying conditions. It can be a one-time or recurring event.

Often, an aura (vision, taste, smell, or sensory changes) will signal an oncoming seizure.

A tonic-clonic seizure occurs in two phases and usually only lasts for a few minutes. First, loss of consciousness occurs. This is followed by convulsions, or violent muscle contractions. The person may also bite the cheek or tongue, lose bladder or bowel control, clench the teeth or jaw, or have a blue skin color.

Following the seizure, a person will probably be sleepy and confused with no memory of the event. A severe headache afterward is also common. It may take a few hours before the person starts feeling normal.

Keep in Mind

Anyone experiencing a tonic-clonic seizure should seek medical help. Treatment will depend upon the cause and often includes the use of anti-seizure medications.

While medications can minimize the effects of seizures, living with chronic seizures can still be frightening and disruptive to daily life. Support groups and online forums are valuable resources for people with epilepsy and other seizure disorders.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.