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Blackouts, seizures and epilepsy, a calm hub for a frightening moment.

Not every blackout is a seizure, and not every seizure is epilepsy. A structured NICE-aligned work-up separates the common vasovagal faint from the cardiac red flag and the first epileptic event.

A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against NICE CG109, NG217, ILAE 2017 classification and MHRA safety updates you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance including the 2024 pregnancy prevention programme for valproate and newer agents like cenobamate.

Key facts

Blackouts, seizures and epilepsy at a glance.

The essentials, in plain English - the three big categories, the tests that matter first, and the NICE-mandated timelines.

  • What it is

    Transient loss of consciousness (TLoC) covers vasovagal syncope, cardiac syncope and epileptic seizures. Each has a very different work-up and treatment.

  • Most common cause

    Vasovagal (reflex) syncope with a classic prodrome of light-headedness, sweating, pallor and tunnel vision before a brief faint.

  • The dangerous one

    Cardiac syncope with no warning, on exertion or lying flat, or with a family history of sudden cardiac death. Needs urgent cardiology.

  • Epilepsy definition

    Two or more unprovoked seizures, or one with a high recurrence risk on EEG or MRI. Classified by ILAE 2017 into generalised and focal.

  • First test always

    A 12-lead ECG after every first TLoC to look for long QT, Brugada, block or ischaemia. Bloods for glucose, electrolytes, calcium and magnesium.

  • First fit clinic

    NICE mandates a first seizure clinic review within two weeks, with EEG within two weeks and MRI brain within four weeks of the first event.

Why this guide matters

Three broad causes, one calm pathway.

Almost every collapse fits into one of three groups. Getting the category right is what separates a reassuring visit from a life-saving one.

  • Vasovagal (reflex) syncope

    The most common cause. A clear prodrome of light-headedness, sweating, pallor and tunnel vision, often triggered by standing, pain, blood-taking, coughing or emotion.

  • Cardiac syncope - the red flag

    No warning, on exertion, on lying, with chest pain or palpitations, or with a family history of sudden death. Think long QT, Brugada, HCM, VT, heart block, aortic stenosis or PE.

  • Epileptic seizures

    Generalised (tonic-clonic, absence, myoclonic, atonic) or focal (aware, impaired awareness, evolving to bilateral tonic-clonic). Classified under ILAE 2017.

How the diagnosis is made

From first blackout to a clear plan.

The steps a UK GP, cardiologist or neurologist will normally follow, aligned with NICE CG109 and NG217.

  1. 01

    Assessing

    Detailed history and eyewitness account

    Prodrome, trigger, posture, duration, tongue-biting (lateral suggests seizure), incontinence, injury and post-event confusion. A phone video from a witness is invaluable.

  2. 02

    Assessing

    Cardiovascular and neurological exam

    Heart sounds, murmurs (aortic stenosis, HCM), focal neurology and lying and standing blood pressure to catch orthostatic drops.

  3. 03

    Assessing

    12-lead ECG for every first TLoC

    Mandatory in all NICE CG109 pathways. Assess the QT interval, look for Brugada pattern, heart block, ventricular pre-excitation and signs of ischaemia.

  4. 04

    Confirming

    Bloods and pregnancy test

    Glucose, sodium, calcium, magnesium and a beta-hCG in women of childbearing potential. Hypoglycaemia and electrolyte shifts mimic seizures.

  5. 05

    Confirming

    EEG within two weeks of a first seizure

    Standard interictal EEG per NICE. A normal EEG does not exclude epilepsy. Sleep-deprived, prolonged or video EEG is used for atypical events and suspected PNES.

  6. 06

    Confirming

    MRI brain within four weeks

    For every first unprovoked seizure, unless clearly febrile in a child or plainly provoked. Looks for structural lesions, hippocampal sclerosis and vascular anomalies.

  7. 07

    Refining

    Holter, loop recorder or tilt-table

    When cardiac syncope is suspected. An implantable loop recorder catches infrequent arrhythmia. Head-up tilt-table is reserved for unclear reflex syncope.

NICE target: first fit clinic within two weeks, EEG within two weeks and MRI brain within four weeks of a first seizure.

Symptoms

What blackouts and seizures actually look like.

The clinical patterns that steer the diagnosis - and the features that mean this is a red flag, not a routine faint.

  • Vasovagal prodrome

    Light-headedness, sweating, pallor, nausea and tunnel vision seconds before a brief faint. Recovery within seconds of lying flat.

  • Cardiac red-flag faint

    Sudden loss of consciousness with no warning, on exertion or lying down, or with palpitations, chest pain or family history of sudden death.

  • Generalised tonic-clonic seizure

    Sudden stiffening then rhythmic jerking of all limbs, lasting one to three minutes, with tongue-biting and post-ictal confusion.

  • Focal aware seizure

    Focal motor, sensory, autonomic or psychic symptoms with preserved awareness. Was previously called simple partial seizure.

  • Focal impaired-awareness seizure

    Blank staring, automatisms (lip-smacking, fumbling) and impaired awareness. May evolve to a bilateral tonic-clonic seizure.

  • Absence and myoclonic events

    Brief blank spells in children (absence) or sudden shock-like jerks on waking (myoclonic). Both point to a generalised epilepsy syndrome.

  • Orthostatic and situational syncope

    Faints on standing, after passing urine, coughing, defaecation or venepuncture. Common in older adults and easily overlooked.

  • Red flag - status epilepticus

    A seizure lasting five minutes or more, or repeated seizures without full recovery. A medical emergency needing 999 and IV benzodiazepines.

Treatment

How blackouts, seizures and epilepsy are treated in the UK.

Treat the underlying cause first. For confirmed epilepsy, NICE NG217 sets a clear ladder from first-line monotherapy through combination therapy, newer agents and, for drug-resistant disease, surgery, VNS, DBS and dietary options.

  • Treat the underlying cause

    Correct hypoglycaemia, electrolyte disturbance, arrhythmia or structural heart disease. Many single events do not need long-term antiseizure medication.

  • Lamotrigine or levetiracetam

    First-line for focal epilepsy and for generalised tonic-clonic seizures in women of childbearing potential per NICE NG217.

  • Sodium valproate

    Highly effective for generalised epilepsy in males and non-pregnant women. Mandatory pregnancy prevention programme since 2018, tightened again in 2024.

  • Ethosuximide for absence

    First-line for childhood absence epilepsy, with valproate and lamotrigine as alternatives.

  • Newer agents for drug resistance

    Perampanel, brivaracetam, cenobamate, eslicarbazepine and lacosamide add options when two first-line drugs fail.

  • Emergency care for status

    IV lorazepam or buccal midazolam, then IV phenytoin, levetiracetam or valproate. Refractory and super-refractory status needs ITU-level care.

  • Surgery, VNS, DBS and LITT

    For drug-resistant focal epilepsy - resective surgery, hemispherectomy, vagus nerve stimulation, deep brain stimulation and laser interstitial thermal therapy at specialist centres.

  • Ketogenic diet and MDT support

    Dietary therapy for paediatric refractory epilepsy, with adult trials in select centres. Neurology, epilepsy nurse, neuropsychology and psychology all sit in the same team.

Specialist centres

Drug-resistant epilepsy is worked up and, where appropriate, operated on at UK specialist centres including the National Hospital Queen Square and Chalfont, King's College Hospital, Cambridge (Addenbrooke's), Manchester, Bristol, Alder Hey and Great Ormond Street. The MDT typically includes neurology, a specialist epilepsy nurse, neuropsychology, psychology and clinical genetics.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, ILAE classification and MHRA safety updates, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, cardiologist or neurologist knows your history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Transient loss of consciousness (blackouts) in over 16s (CG109).

  • NICE. Epilepsies in children, young people and adults (NG217).

  • ILAE 2017 operational classification of seizure types and epilepsies.

  • MHRA. Valproate pregnancy prevention programme (2018) and 2024 tightening for men and women under 55.

  • DVLA. Assessing fitness to drive - a guide for medical professionals (neurological and cardiovascular chapters).

  • Epilepsy Action and Epilepsy Society - UK patient support and SUDEP guidance.

Red flags

When a blackout or seizure needs urgent attention.

Most single blackouts are benign. These are the situations that are not - and where same-day specialist input is essential.

  • Cardiac syncope pattern

    No warning, on exertion, lying flat, or with palpitations, chest pain or a family history of sudden death under 40. Needs same-day cardiology assessment.

  • Status epilepticus

    A seizure lasting five minutes or more, or repeated seizures without recovery between them. Call 999 - IV benzodiazepines are time-critical.

  • First seizure in an adult

    Any first unprovoked seizure needs a first fit clinic review within two weeks, plus EEG within two weeks and MRI brain within four weeks per NICE.

  • Head injury or focal neurology

    Persistent headache, weakness, speech disturbance or a fall from height after the event. Consider urgent CT to exclude bleeding or a structural lesion.

  • Pregnancy and antiseizure medicines

    Valproate carries a 30 to 40% risk of major malformation and neurodevelopmental effects. Topiramate increases cleft palate risk. Plan pregnancy with a specialist.

  • SUDEP risk

    Sudden unexpected death in epilepsy is higher with poorly controlled generalised tonic-clonic seizures. Optimise control and discuss safety openly.

  • New seizures over 50

    New-onset seizures in older adults raise the index of suspicion for stroke, tumour or neurodegenerative disease. Imaging is not optional.

  • Reflex or exertional syncope on the road

    DVLA rules apply - Group 1 six months seizure-free, Group 2 five years, four weeks for uncomplicated reflex syncope. Not driving is a legal duty.

  • PNES (dissociative seizures)

    Not epilepsy - but real, disabling and treatable. Video-EEG confirms the diagnosis and psychology-led therapy is the mainstay.

Living with it

A treatable condition, with a clear plan.

Four things that make the biggest difference day to day - practical safety, DVLA rules, pregnancy planning and knowing where to find support.

A quiet reminder

Consistency beats intensity, every time.

Take medication every day, at the same time, and never stop it suddenly. Most people with epilepsy live full lives.

  1. 01 Safety

    Practical seizure safety

    Shower rather than bathe, avoid heights and open water alone, tell close contacts what to do and consider a medical ID.

  2. 02 Driving

    Know the DVLA rules

    You must tell the DVLA after any TLoC. Group 1 needs six months seizure-free, Group 2 five years, and four weeks for uncomplicated reflex syncope.

  3. 03 Pregnancy

    Plan pregnancy early

    Discuss medication choice, folic acid and specialist obstetric care well before conception. Never stop antiseizure medication suddenly.

  4. 04 Support

    Charities and epilepsy nurses

    Epilepsy Action and Epilepsy Society offer helplines, apps and peer support. Your specialist epilepsy nurse is often the fastest route to advice.

Frequently asked

Everything we get asked about blackouts and seizures.

Quick answers on faints, seizures, tests, medication and driving.

  • What is the difference between a faint and a seizure?

    A faint (syncope) is a brief drop in blood flow to the brain, usually with a warning of light-headedness, sweating and pallor, and quick recovery once lying flat. A seizure is abnormal electrical activity in the brain, often with stiffening, jerking, tongue-biting to the side and several minutes of post-event confusion. Only a specialist review with a careful history, ECG, EEG and often MRI can be sure.

  • What is transient loss of consciousness (TLoC)?

    TLoC is the umbrella term for any brief loss of consciousness. NICE CG109 splits it into three broad groups: vasovagal (reflex) syncope, cardiac syncope and epileptic seizures. The work-up starts the same way every time - a detailed history, an eyewitness account, cardiovascular and neurological examination, a 12-lead ECG and appropriate bloods.

  • When is a seizure an emergency?

    Call 999 for any seizure lasting five minutes or more, repeated seizures without recovery between them (status epilepticus), a first ever seizure, injury during the seizure, breathing difficulty afterwards, or a seizure in pregnancy. Status epilepticus needs IV benzodiazepines (lorazepam or midazolam) followed by phenytoin, levetiracetam or valproate.

  • What tests do I need after a first blackout?

    A 12-lead ECG is mandatory. Blood tests include glucose, sodium, calcium, magnesium and a pregnancy test where appropriate. For a suspected first seizure, NICE requires review at a first fit clinic within two weeks, an EEG within two weeks and an MRI brain within four weeks. Suspected cardiac syncope adds Holter monitoring, sometimes an implantable loop recorder and occasionally a tilt-table.

  • What medication is used for epilepsy?

    NICE NG217 recommends lamotrigine or levetiracetam as first-line for focal epilepsy. For generalised tonic-clonic seizures, sodium valproate is highly effective in males and non-pregnant women, and lamotrigine or levetiracetam is first-line for women of childbearing potential. Absence seizures use ethosuximide, valproate or lamotrigine. Drug-resistant epilepsy adds newer options like perampanel, brivaracetam, cenobamate, eslicarbazepine and lacosamide.

  • Can I drive after a blackout or seizure?

    You must inform the DVLA. For epileptic seizures, Group 1 (car and motorbike) licence holders need six months seizure-free (longer in some patterns), and Group 2 (lorry and bus) need five years off medication and seizure-free. Uncomplicated reflex syncope is usually four weeks for Group 1. Rules change often - always check the latest DVLA guidance and speak to your specialist.

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