What is epilepsy?

Epilepsy is a neurological condition that affects an estimated 600,000 people and their families in the UK. It commonly starts in childhood.


A seizure is a change in sensation, awareness, behaviour or movement that can be detected as an electrical disturbance in the brain.

Seizures vary from a momentary disruption, to short periods of unconsciousness or staring spells, altered consciousness to convulsions.

Some people have just one type of seizure. Others have more than one type.

‘Epilepsy syndromes’

Doctors recognise a number of ‘epilepsy syndromes’. A syndrome is a collection of features. 

In the case of an epilepsy syndrome, these features will be things such as age at onset of seizures, the seizure types and the EEG pattern. 

An EEG (electroencephalogram) uses leads on the surface of the scalp to detect patterns of brain waves.  

The diagnosis of an ‘epilepsy syndrome’ may provide clues about the underlying cause of the epilepsy. It may also provide clues about which medications are likely to work best. 

However, many people with epilepsy do not have a pattern suggesting a specific epilepsy syndrome.    

What causes a seizure?

Epilepsy is usually caused by a combination of factors, Many of these factors are poorly understood. 

Triggers for seizures in some people include:
  • not taking epilepsy medicine reliably
  • coming off an epilepsy medication too quickly
  • stress
  • not sleeping well
  • too much alcohol
  • missing meals
  • in rare cases, specific stimuli such as strobe lights

Causes of epilepsy

Many people with epilepsy will have no obvious reason why they have developed it. In some cases the epilepsy is due to a previous illness. Examples would be a previous stroke or meningitis. The way that genes programme nerve cells to transmit messages may also make epilepsy more likely. Although they look different, all seizures are caused by a sudden change in how brain cells send chemical and electrical signals to each other. Good seizure control can sometimes take a long time to achieve. In a small proportion of people with epilepsy it may be impossible to control all seizures. 

Side-effects of epilepsy medicine

Like all medicines, epilepsy medicine may have both the desired effect of controlling seizures and undesirable side-effects. Some of these side-effects are dose-related and occur only when a person is taking high levels of medication.

Other side-effects may occur regardless of dose and some may be an allergic type of reaction, such as a rash. Side-effects tend to be more common when starting a drug or changing the dosage.

Epilepsy and related conditions

Some children have severe forms of epilepsy or syndromes that are difficult to treat with medicines. They may continue to have seizures.

Children with difficult to control epilepsy may have other conditions, such as: 

Epilepsy – further information

Thanks to Dr Andrew L Lux, Consultant Paediatric Neurologist, Bristol Royal Hospital for Children, for reviewing this content in 2016.

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