Understanding seizure types
Tonic-Clonic Seizures
Tonic-clonic seizures cause a loss of consciousness, muscle stiffening, and rhythmic jerking. Knowing what to do can help protect the person and ensure they receive help when needed.
About this information
This webpage is subject to continuous review by Epilepsy Ontario to help keep the information current. This material is for informational purposes only and should not be used for self-diagnosis or as a substitute for professional medical advice, diagnosis, or treatment. Consult your healthcare provider about your own health and care.
What happens during the seizure?
Tonic phase
The muscles stiffen
The person loses consciousness and their muscles become stiff. They may fall if standing. Air moving through the vocal cords can produce a sound or cry.
Clonic phase
The body jerks rhythmically
Repeated jerking follows the stiffening. Breathing may change, saliva may collect around the mouth, and the person may bite their tongue or lose bladder control.
How do tonic-clonic seizures begin?
Generalized tonic-clonic seizures involve networks on both sides of the brain from the beginning.
Focal-to-bilateral tonic-clonic seizures begin in a network on one side of the brain and spread to involve both sides. Some people notice an initial symptom, sometimes called an aura, before losing consciousness.
When the beginning is not known, further assessment may be needed to determine the classification. The older term “grand mal” is no longer preferred.
How to help
Stay calm. Protect. Time the seizure.
During the seizure
- Stay with the person and note the start time.
- Clear nearby objects and cushion their head with something soft.
- Ease them to the ground if you can do so safely.
- Do not restrain them or try to stop the movements.
- Do not put anything in their mouth.
As the movements stop
- Gently position them on their side when safe.
- Check their breathing and stay nearby.
- Speak calmly and protect their privacy.
- Do not give food, drink, or pills until fully alert and able to swallow safely.
- Follow their individual seizure action plan.
When to call 911
- The seizure lasts longer than five minutes.
- Another seizure begins before the person recovers.
- There is difficulty breathing or waking afterward.
- The person is injured or the seizure occurs in water.
- This is their first known seizure.
- The person is pregnant, or has diabetes and loses consciousness.
- Their seizure action plan directs you to call.
Do not wait five minutes if another emergency sign is present.
If the person is unresponsive and not breathing normally after the movements stop, call 911, start CPR, and use an AED if available. Follow the dispatcher’s instructions.
Recovery deserves attention
Afterward, the person may be tired, confused, sore, or have a headache. Recovery varies. Provide reassurance and a safe place to rest while continuing to monitor them.
Do not assume that ongoing unresponsiveness or abnormal breathing is simply sleep. Seek emergency help when recovery is concerning.
Treatment and planning
Treatment depends on the type of epilepsy and the person’s needs. Ask the healthcare team about seizure control, safety, and whether prescribed rescue medication should be included in an individual action plan.
Use rescue medication only as prescribed and according to the training and instructions provided. It does not replace calling 911 when emergency help is needed.
Watch: a tonic-clonic seizure
This educational video shows one example. Seizures and recovery can look different from person to person.
