Have you ever had a tonic-clonic seizure? Or, perhaps you have seen someone else having one. Tonic-clonic seizures are probably the most well-known type of epileptic seizure. About a quarter of people with epilepsy have tonic-clonic seizures.
In this article, you’ll learn more about what tonic-clonic seizures are and how they’re treated. If you have tonic-clonic seizures, speak with your doctor for more information about managing them.
What is a tonic clonic seizure?
A tonic-clonic seizure occurs when unusual electrical activity happens in the brain. The electrical activity usually starts on both sides of the brain at once (although it may begin at one point and spread from there).
The ‘tonic’ phase of the seizures make people’s muscles tense up, which may cause them to fall over if they are standing. Their bodies, legs and arms then jerk uncontrollably - this is known as the ‘clonic’ phase, where their muscles rapidly contract. People who have tonic-clonic seizures are unconscious during the seizure itself and it may take them some time to recover after the seizure has ended.
Tonic-clonic seizures used to be called ‘grand mal’ (French for ‘great evil’).
Tonic clonic seizure symptoms
Tonic clonic seizures often (but not always) go through the following stages:
1. Prodromal phase
About 20% of people experience a ‘prodromal phase’. This can happen days or hours before the seizure itself begins. They might feel confused, anxious, irritable or have a headache.
2. Aura
Many (but not all) people experience auras shortly before the seizure itself, where they may have strange sensations, notice odd tastes and smells or see unusual colors. Some people interpret this as a ‘warning’ that a seizure may shortly happen.
Learn more: What is an aura?
3. Tonic phase
During the tonic phase, people typically lose consciousness and their muscles go stiff. If they were standing, they may suddenly go stiff and fall over. Also, as the air is forced from their lungs, they may shout out. Sometimes, people bite their tongue. The tonic phase often lasts around 10-20 seconds. One study calculated the mean time for each phase of a tonic-clonic seizure for different 153 people who had 275 seizures. The mean duration of the tonic phase was 11.6 seconds.
4. Clonic phase
During the clonic phase your legs and arms will jerk and shake uncontrollably and you may clench your jaw. You may also lose control of your bladder (wet yourself). The clonic phase usually lasts around one minute, but can last for up to three minutes or more.
If a tonic clonic seizure continues for longer than FIVE minutes (or the person stops then starts clonic seizures without regaining consciousness) it is a medical emergency and an ambulance must be called.
5. Post-ictal phase
This is the final phase. After experiencing a tonic-clonic seizure, people often need to sleep. They may feel confused and in pain, and have a bad headache.
Learn more: What happens in your brain during a seizure
First response tonic clonic seizure treatment
Your doctor can provide you with information about how to prepare for tonic-clonic seizures.
Some people with epilepsy find it helpful to share information to their friends and family so they know how to respond in case they have a tonic-clonic seizure. The CDC has an extensive guide on seizure first aid - and includes ideas people can share with friends and family like:
- Don’t try and hold me down or stop me from moving
- Try and clear space around me so I don’t hurt myself
- If possible, gently move me onto my side (the recovery position)
- Do not try and force anything into my mouth (it is impossible for me to swallow my tongue)
- Stay with me until the seizure is over
- Check your watch - if the seizure continues for more than five minutes, call 911
By educating yourself about this kind of seizure and learning about tonic-clonic seizure treatment and management, you may feel more confident going forward. Speak with your doctor for more advice about living with tonic-clonic seizures.
