Tonic seizures can be generalised onset, meaning they affect both sides of the brain from the start. Or they can be focal onset, meaning they start in just one side of the brain.
What happens during a tonic seizure?
If a tonic seizure starts in both sides of the brain, all your muscles tighten and your body goes stiff. If you’re standing, you may fall to the floor. Your neck will extend, your eyes open wide and roll upwards. Your arms may raise upwards and your legs stretch or contract. You may cry out and stop breathing during the seizure.
If a tonic seizure starts in one side of the brain your muscles tighten in just one area of the body.
How long do tonic seizures last?
Tonic seizures usually last less than 60 seconds.
What happens after a tonic seizure?
Once a tonic seizure has ended your muscles relax. You might feel sleepy or confused afterwards.
How can someone help me during a tonic seizure?
Ask them to take our short online course which shows them what to do when someone has a seizure.
See this information with references
If you would like to see this information with references, visit the Advice and Information references section of our website. If you are unable to access the internet, please contact our Epilepsy Action Helpline freephone on 0808 800 5050.
Epilepsy Action would like to thank Dr John Paul Leach, consultant neurologist at the Queen Elizabeth University Hospital, Glasgow, for this contribution to this information.
Dr Leach has declared no conflict of interest.
This information has been produced under the terms of Epilepsy Action's information quality standards.
- Updated July 2019To be reviewed July 2022