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Tonic-clonic seizures

Tonic-clonic seizures are the type of epileptic seizure most people recognise. In the past they were called grand-mal seizures.

Tonic-clonic seizures can have a generalised onset, meaning they affect both sides of the brain from the start. When this happens, the seizure is called a generalised tonic-clonic or bilateral convulsive seizure.

Some seizures start in one side of the brain and then spread to affect both sides. When this happens it’s called a focal to bilateral tonic-clonic seizure.

What happens during a tonic-clonic seizure?

There are 2 phases in a tonic-clonic seizure: the ‘tonic’ phase, followed by the ‘clonic’ phase.

During the tonic phase:

  • You lose consciousness, so you won’t be aware of what’s happening
  • All your muscles go stiff, and if you’re standing you fall to the floor
  • Air might push past your voice box, which can make a sound like you’re crying out
  • You may bite down on your tongue or inside your mouth

During the clonic phase:

  • Your limbs jerk quickly and rhythmically
  • You may lose control of your bladder and/or bowels
  • Your breathing may be affected, causing a blue tinge around your mouth

Focal to bilateral tonic-clonic seizures

If the seizure starts on one side of the brain and spreads to affect both sides, it’s called a focal to bilateral tonic-clonic seizure. If you have this type of seizure, you might get the symptoms of a focal seizure immediately before you lose consciousness. Examples of these symptoms are feeling frightened, having a rising sensation in your stomach or smelling something that’s not there. This can act as a warning that you’re about to have a tonic-clonic seizure. Some people call this warning an aura.

How long do tonic-clonic seizures last?

Most tonic-clonic seizures last between one and 3 minutes. If a tonic-clonic seizure lasts longer than 5 minutes you may need emergency medical treatment.

What happens after a tonic-clonic seizure?

After a tonic-clonic seizure, you might have a headache and feel sore, tired and very unwell. You might feel confused, or have memory problems. You might go into a deep sleep. When you wake up, minutes or hours later, you might still have a headache, feel sore and have aching muscles.

The length of time it takes to recover after a tonic-clonic seizure is different from one person to the next. Some people feel better after an hour or 2, but for some people it can take several days to feel ‘back to normal’.

Some people find they have temporary weakness or can’t move part of their body after they’ve had a seizure. This is called Todd’s paresis or Todd’s paralysis. It can last from a few minutes up to 36 hours, before going away.

How can someone help me during a tonic-clonic seizure?

There are simple first-aid steps people around you can take, to keep you safe during a tonic-clonic seizure. See our first aid information, or 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 2019
    To be reviewed July 2022

Comments: read the 9 comments or add yours


hi i am a 66yr old female i had my first fit begining of march 2017 nd 6wks later had another. i have no memory of having the previous seizure in fact i no memory of anything . i have a gap of six wks i do not remember anything except waking up in hospital bed after the second fit even that is vague, i have to accept that iam not going to get my memory back after a struggle of trying is this usual. finally i am diagnosed with focal tonic clonic seizures,

Submitted by veronica on

I found this site while looking for information on epilepsy for my cat. Very interesting. She suddenly developed epilepsy after her last vaccination. After reading all the comments as well as comments from other sites I have a new understanding and sympathy for people struggling with epilepsy. I never knew before how awful it is.
My cat, I think, has photo sensitive tonic clonic seizures. Her seizures always happen after she runs up the stairs (shapes and patterns) and she has all the tonic clonic symptoms. I wish I could tell her to cover one eye with her paw.
The vet has prescribed phenobarbitol and she will need to have liver function tests every 3 to 6 months. I worry that this will cause her extreme stress as she is very feisty and has to be sedated and have her neck fur shaved each time so they can draw blood. I have delayed starting the treatment and am experimenting with cbd oil and a herbal tincture twice per day. Her seizures have gone from every 2 or 3 three days to about every 8 or 9 days. I have been keeping a diary. Again, thanks for this site. Extremely interesting and helpful and my best wishes to all the sufferers out there.

Submitted by Tanya Cameron on

I have 2 types of epilepsy focal and tonic-clonic, both my parents have epilepsy my father has tonic clonic and my mother had focal, I had fits when I was a baby but they put it down to over heating but then it came back when I began high school, I am now 21 years of age and I've moved in with my boyfriend of two years a month ago he has seen me have many fits before now and knows how to look after me after a fit but him being constantly worried about me makes me feel full of guilt constantly like I'm taking his freedom away from him on times, I don't know if anyone would have the answer but is there any way that I could at least support him in a way that he doesn't have to constantly worry just about me? Thanks.

Submitted by Nakea on

Hi Nakea

Thank you for your comment.  It sounds like you have a very caring boyfriend.

To help people stay safe we have information on  safety, safety in the home and daily living aids that may help.

In the daily living aids information, you will find information on various alarm systems. The wrist-worn sensors or seizure alert subscription services that could be a way to alert your boyfriend or others when you have a seizure.

As you are still having seizures, I’d like to check you’re seeing an epilepsy specialist? An epilepsy specialist can review your treatment and look at other possible reasons for why your seizures are still happening. They may suggest trying a different epilepsy medicine.  If you have tried various types of epilepsy medicines, it may be the specialist could look into other treatment options for you.

We also have information on getting the right treatment that includes information for people who have difficult to control epilepsy.

If you are not under a specialist, you will need to ask your family doctor to refer you. This would usually be to a neurologist. The ideal would be to someone with a specialist interest in epilepsy, as there are many different neurological conditions, and neurologists tend to specialise in different ones.

I hope this is of help for you both. If we can be of any more help, please feel free to contact us again. You can do this directly by email helpline@epilepsy.org.uk or the Epilepsy Action Helpline freephone 0808 800 5050. Our helpline is open Monday to Thursday 8.30am until 8.00pm, Friday 8.30am until 4.30pm and Saturday 10.00am until 4.00pm.



Epilepsy Action Helpline Team

Submitted by rich on

my seizures started about 6/7 years ago i have no recolection of them and the thing i find hardest is when i go doctors still to this day they try taking me off of other medication , ive been reduced and increased and even one doctor took me off them completely , i havent had a specialist appointment for years and never really got anything explained . Recently ive been having fits again and one i fitted and grabbed hold of a boiling radiator from the wall and ended up with burns and scars and ive split my eye open only the other day . This is a very tender condition as i never know what or when things are going to happen and that is very scary .

Submitted by peter watson on

Hi I’ve been epileptic since birth , 49yr grand- mal, peti-mal recently done trial with clobazam as well as my phenytoin because I was having absences , I ended up in hospital with my phenytoin levels being very high through clobazam they said , I was having different type of seizure ie: auras before them I’ve never had a aura before with my original ones , either funny taste , my tongue and gums swell , now I’ve been diagnosed with non- epileptic seizure through the levels of phenytoin these types wears me out even more and I find these confusing too , are these common thanks for reading

Submitted by Kristine balmer on

I was diagnosed with Primary Reading Epilespy when i was 21. It really does have quite a big impact on your life and this type of epilpesy is quite hard to deal with as you read every day. I decided to take medication which has side effects and the most notable one is that of memory loss and retention. This can be quite hard in the my chosen career of IT and when it comes to theory in IT memory plays quite a big part. Most of my learning has completed by doing rather than reading. Always happy to help anyone if they have any questions around getting the best out of your job whilst coping with this type of epilpesy and the side effect of memory loss due to medication.

Submitted by Karl on

I (59 years old),had my very first seizure in Tesco on 22nd may,collapsing to the floor, and biting my tongue,as well as losing consciousness.It was reported that there was a witness account of 2 minutes Tonic Clonic activity.After being taken to hospital,and having an ECG, a CT scan,blood tests and various other tests,to eradicate heart attack,stroke etc,it was recorded as a First Seizure.I cannot remember anything on that day before the seizure.I don't remember dropping my wife off at work, driving to Asda to buy milk,then driving on to Tesco where I collapsed in the store.Today,8 days later,I had an appointment at the First Seizure Clinic in the hospital, and was told that I had an "Epileptic Seizure".I queried it being epilepsy based on the documentation from the hospital saying all the tests,scans etc carried out showed everything was normal.The Neurologist stated that there needs to be at least 2 seizures before they can categorically state it is epilepsy.He went on to say "That is why I have said it is an Epileptic Seizure"."Because we're not allowed to say that you are epileptic until you have at least 2 seizures.He wanted to put me on medication there and then,but I declined saying that I am not certain it is epilepsy, as the hospital test results did not show anything conclusive.My wife seems to think I collapsed due to dehydration,but I drink plenty of fluids each day.I am not 100% certain that I have epilepsy,even though I have a twin brother who is registered epileptic,but has not had any seizures for 18 years,due to his medication he is on.4 hours before my neurologist appointment today,I was walking to my wifes workplace when I suddenly had a dizzy spell, and my vision becoming blurred.This lasted for about 10 seconds.Was that a minor warning sign that an epileptic seizure is on its way?.Also,in the past,sort of like a month or 3 ago, sometimes when shopping,I look at the goods on the shelf and I can't see what is on the shelf,my eyes are seeing red and blue flashes.Is this a signal of epilepsy?.I really don't want to start medication for epilepsy if it is not proven that I have it.I don't want to be taking medication for something i haven't got.On the other hand,if i have got epilepsy,then I need to be on medication as soon as possible.Any help ,advice,replies etc,would be greatly appreciated.

Submitted by michael hickley on

Dear Michael,

Thank you for your comment. 

It’s a lot to take in when you’ve just had a first seizure. It might be useful to keep a diary of the symptoms you’re experiencing, including the dizziness and vision problems. This can help you see whether there’s a pattern to the symptoms, or if they increase, and can be useful to show your doctors. 

Some kinds of focal seizures can cause unusual visual symptoms or dizziness. For some people these are a ‘warning’ before a tonic clonic seizure, or they can happen on their own. Focal seizures are caused by unusual electrical activity in a small part of your brain, as opposed to tonic clonic seizures which affect your whole brain. 

I’m not sure whether you’ve had an EEG test (you mention an ECG). If you did and the results came back normal, this could be because the electrical activity in the brain that indicates epilepsy was not happening at the exact time of the scan. This can be quite common. You might like to read the rest of our information about the different tests and diagnosis. 

It's a big decision whether or not to start taking epilepsy medicine after a first seizure. They don’t cure the epilepsy, but try and stop the seizures happening. They do this by changing the levels of chemicals in the brain that control electrical activity. Many people, such as your brother, achieve seizure control with medicine. It can take some time to find the right dose of the right medicine for each person. 

If we can be of any more help, please feel free to contact us on the Epilepsy Helpline freephone 0808 800 5050. We are open Monday to Thursday  8.30 am until 8.00pm, Friday 8.30 am to 4.30 and Saturday 10 am to 4 pm.



Epilepsy Action Helpline Team

Submitted by Ashley - Epilep... on

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