There are many different types of seizures. This information is for people affected by or concerned about generalised seizure types. On this page we tell you about the most common generalised seizure types.
Use this page as a general guide and speak to a health professional for more information and support.
A generalised seizure (or generalised onset seizure) affects both sides of the brain from the start. It causes you to black out (lose consciousness). Sometimes, the period of unconsciousness is so short it may not even be noticed.
Before a generalised seizure, you may have unusual symptoms that could be a sign your seizure is starting. This warning is also known as an ‘aura’. It’s likely that this warning will happen at the beginning of the seizure in just one part of the brain, before it spreads to the whole brain. If you do get this warning, try to get into a safe place, even if that’s just sitting on the floor.
Seeing anyone have a seizure can be quite frightening. It can be especially worrying when the person having a seizure is a baby or child. But it’s important to remember that if they’re unconscious during generalised onset seizures, they will not be aware of what’s happening, and they usually recover quickly.
Tonic-clonic seizures are the most commonly recognised type of seizure. They used to be called grand mal seizures. This type of seizure has a 'tonic' phase, where the muscles tighten, and a clonic phase, where the body shakes. They are caused by abnormal electrical activity across the whole brain and usually comes with reduced awareness or a complete loss of consciousness.
You told us what really helps when you're having a seizure, and we listened. This guidance is shaped by a powerful mix of lived experience and clinically informed expert advice, coming together to help others know what to do.
To help someone who is having a tonic-clonic (convulsive) seizure, follow these steps:
Call an ambulance if:
The person may have an emergency management or care plan. If they do, you should follow the instructions in their plan. Their plan may include giving them their prescribed emergency medication, but do not administer emergency medication unless you are trained to do so. If you have to call 999, stay on the line and follow the guidance of the call handler.
Tonic seizures can are not always generalised seizures (affecting both halves of the brain), and sometimes only affect half the brain. The name ‘tonic’ means an ‘increase in tone or tightness’, as these seizures can cause the muscles in your chest, arms and legs to contract, making your body become stiff. Your back may also arch and your breathing may change.
To help someone who is having a tonic seizure, follow these steps:
Call an ambulance if:
The person may have an emergency management or care plan. If they do, you should follow the instructions in their plan. Their plan may include giving them their prescribed emergency medication, but do not administer emergency medication unless you are trained to do so. If you have to call 999, stay on the line and follow the guidance of the call handler.
Atonic seizures can be seen as the opposite of tonic seizures, although both types can be generalised (affecting both half the brain) or focal (affecting one side). During an atonic seizure muscle tone is reduced instead of tightened, which causes you to suddenly fall to the ground. Atonic seizures are sometimes called ‘drop attacks’.
You told us what really helps when you're having a seizure, and we listened. This guidance is shaped by a powerful mix of lived experience and clinically informed expert advice, coming together to help others know what to do.
Even though these seizures only last a few seconds, someone having one still needs your help.
To help someone who is having an atonic seizure, follow these steps:
Call an ambulance if they’ve seriously injured themself.
The person may have an emergency management or care plan. If they do, you should follow the instructions in their plan. Their plan may include giving them their prescribed emergency medication, but do not administer emergency medication unless you are trained to do so. If you have to call 999, stay on the line and follow the guidance of the call handler.
Absence seizures are a type of generalised seizure that used to be called petit mals. Absence seizures often begin in childhood and are sometimes mistaken for daydreaming. They do not usually continue into adulthood, although they can do continue in some types of epilepsy.
You told us what really helps when you're having a seizure, and we listened. This guidance is shaped by a powerful mix of lived experience and clinically informed expert advice, coming together to help others know what to do.
To help someone who is having an absence seizure, follow these steps:
Call an ambulance if they’ve seriously injured themself.
The person may have an emergency management or care plan. If they do, you should follow the instructions in their plan. Their plan may include giving them their prescribed emergency medication, but do not administer emergency medication unless you are trained to do so. If you have to call 999, stay on the line and follow the guidance of the call handler.
Myoclonic seizures can be both generalised (affecting both sides of the brain) and focal seizure types (affecting one side), and you are usually aware when having them. During this type of seizure, you might jerk your limbs, roll your eyes, blink, nod, make sounds, or fall to the ground (if you’re standing).
You told us what really helps when you're having a seizure, and we listened. This guidance is shaped by a powerful mix of lived experience and clinically informed expert advice, coming together to help others know what to do.
Even though they only last a few seconds, a myoclonic seizure can be scary and confusing for both the person experiencing it and the person witnessing it. But you can help.
To help someone who is having a myoclonic seizure, follow these steps:
Call an ambulance if they’ve seriously injured themself, or if they have lots of seizures in a short space of time.
The person may have an emergency management or care plan. If they do, you should follow the instructions in their plan. Their plan may include giving them their prescribed emergency medication, but do not administer emergency medication unless you are trained to do so. If you have to call 999, stay on the line and follow the guidance of the call handler. Find out more about emergency medication.
Last reviewed July 2025.
Next review due July 2028.
If you would like to find out more about how we produce our information, or the sources of evidence we use, please contact us at healthinfo@youngepilepsy.org.uk
Tonic-clonic seizures used to be called grand mal seizures. They are the type most people recognise. Tonic-clonic seizures are caused by abnormal electrical activity which affects the whole brain.
Absence seizures used to be called petit mal seizures and are more common in young people. Absence seizures are often subtle but are still very serious.
Myoclonic seizures might make you jerk, roll your eyes, blink, nod, make coughing sounds, or fall to the ground (if you’re standing). They can be generalised or focal seizures.
Tonic seizures can be generalised (affecting both sides of the brain from the start) or focal (they start in one side of the brain). The name ‘tonic’ means an ‘increase in tone or tightness’ of the muscles.
Atonic seizures are the opposite of tonic seizures, so during an atonic seizure muscle tone is reduced, which causes you to suddenly flop forward and fall to the ground. This is sometimes called a ‘drop attack’.
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