Collapse and blackout assessment (Assessment of transient loss of consciousness (syncope))
A same-day medical assessment to find out why someone collapsed, fainted or blacked out, used once they have recovered and are stable.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- If someone cannot be woken within a minute, is jerking or shaking, has hit their head, or has chest pain or breathing trouble, call 999 — do not book a private appointment.
- Most blackouts are a simple faint and are not dangerous, but the assessment is there to catch the smaller number caused by a heart or other serious problem.
- The history (including from a witness) and a heart tracing are central; some heart-monitoring tests take days or longer to give answers.
- A blackout can affect whether you are allowed to drive — ask about the rules, and tell the driver licensing authority if required (the DVLA in England, Scotland and Wales, or the DVA in Northern Ireland).
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Identifies the smaller number of dangerous causes, such as a heart rhythm problem, so they can be treated
Anyone who cannot be woken, is fitting, or has chest pain or breathing trouble — they need 999 and emergency care, not a routine assessment.
You have an ECG, blood tests and lying-and-standing blood pressure checks. The clinician takes a detailed history of the event.
Clear written advice on the symptoms that mean you should call 999 again.
You have an ECG, blood tests and lying-and-standing blood pressure checks. The clinician takes a detailed history...
Many results are available. The clinician explains the likely cause and whether you can go home, and gives driving...
If a heart monitor is fitted, it is worn for a set period and then reported. An echocardiogram or neurology...
You are told the cause if found, any treatment, and whether driving restrictions apply. If no cause is found but...
What is a collapse and blackout assessment?
If someone has collapsed and cannot be woken within a minute, is jerking or shaking (a possible fit), has hit their head, has chest pain, or is struggling to breathe, call 999 now. The same applies to a first-ever blackout in someone with heart disease, or a blackout during exercise. These can point to a dangerous heart or brain cause and should not wait for a private appointment.
A collapse and blackout assessment is what happens once the person has recovered and is stable. Doctors use the term 'transient loss of consciousness' for a blackout — a sudden, brief loss of awareness with full recovery. The assessment works out why it happened.
It is usually done by an acute physician or a general physician, and may involve a heart specialist or, where a seizure is suspected, a neurologist. They take a detailed history (including from anyone who saw it happen), examine you, check your heart and blood pressure, and do an ECG and blood tests.
Be clear about the limits. Most blackouts are a simple faint (a brief drop in blood supply to the brain) and are not dangerous. But a small number are caused by a heart rhythm problem or another serious cause, and these matter to find. A normal assessment cannot always promise it will not happen again, especially if the cause is intermittent.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Calling 999 vs booking a private blackout appointment
| Situation | Call 999 / A&E | Private same-day assessment |
|---|---|---|
| Cannot be woken within a minute | Yes — straight away | No — do not delay |
| Jerking, shaking or a possible fit | Yes | No |
| Blackout during exercise, or with chest pain | Yes — possible heart cause | No |
| Recovered fully, simple faint, otherwise well | Use NHS 111 if unsure (GP out-of-hours or Phone First in Northern Ireland) | Reasonable for a stable work-up |
A blackout during exercise, or in someone with known heart disease or a family history of sudden death, should be treated as urgent.
Preparing for your test
- First, check this is not an emergency: someone who cannot be woken, is fitting, has hit their head, or has chest pain or breathing trouble needs 999 now, not an appointment.
- If you have recovered, write down exactly what happened: what you were doing, any warning signs, how long you were out, and how you felt afterwards.
- Bring an account from anyone who saw it — whether you went stiff or jerked, your colour, and how quickly you came round — as this is often the most useful information.
- Bring a full list of your medicines, especially blood pressure tablets, water tablets and anything that affects heart rhythm.
- Note any heart symptoms (palpitations, chest pain, breathlessness) and any family history of heart problems or sudden death at a young age.
- Tell the clinician whether you drive or operate machinery, as a blackout can affect this.
- Bring details of any previous blackouts, heart tests or seizures.
What happens
The clinician first makes sure you are safe and fully recovered. They take a careful history of the event, ideally including an account from a witness, because the description often points to the cause better than any test.
They examine you, check your heart and pulse, and measure your blood pressure lying down and standing up. You will usually have an ECG (a quick, non-invasive heart tracing) and blood tests. If a heart rhythm problem is suspected, you may be fitted with a heart monitor to wear at home, or have an echocardiogram.
If the description suggests a fit rather than a faint, you may be referred to a neurologist, who may arrange a brain scan and an EEG. Not everyone needs these — the assessment is guided by what likely happened.
Before you leave, you should be told the likely cause, what the tests show, whether you need monitoring or a specialist, what it means for driving, and what to do if it happens again.
Is this test right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Anyone who cannot be woken, is fitting, or has chest pain or breathing trouble — they need 999 and emergency care, not a routine assessment.
- A blackout during exercise, or in someone with known heart disease or a family history of sudden death — this needs urgent specialist assessment.
- Settings without quick access to an ECG, heart monitoring and a clear escalation route, as a dangerous heart cause can be missed.
- Someone expecting a guarantee that a blackout will never happen again.
Delay or rearrange if…
- The person has not fully recovered, or there is any ongoing drowsiness, confusion or weakness — seek urgent care instead.
- There was a significant head injury during the collapse that has not been assessed.
- A witness account or medicine list is missing and would change decisions.
- You cannot arrange safe transport or rapid access back to care if it happens again.
Alternatives to discuss
- 999 and A&E for any collapse with danger signs — the safest and fastest route.
- NHS acute medical unit, syncope clinic or rapid-access service for stable cases.
- NHS 111 for advice when you are unsure whether symptoms are urgent — this covers England, Scotland and Wales; in Northern Ireland, contact your GP out-of-hours service or your HSC Trust's Phone First service instead.
- GP review for a clear, typical simple faint with no worrying features, to plan any further checks.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Identifies the smaller number of dangerous causes, such as a heart rhythm problem, so they can be treated
- Reassures the many people whose blackout is a simple faint and not dangerous
- Uses the history and witness account to focus tests sensibly rather than testing everything
- Gives clear advice on driving and safety while the cause is sorted out
- Provides a plan to reduce the chance of it happening again where possible
Risks & complications
- Mild bruising or discomfort from blood tests and ECG stickers
- Waiting around for tests and results
- Not getting a definite answer in one visit if the cause is intermittent
- Temporary restrictions, such as not driving, until the cause is clear
- A heart monitor not capturing an event during the time it is worn
- Incidental findings on scans that then need checking
- Anxiety about when it might happen again
- Needing longer-term monitoring to catch a rare rhythm problem
- A serious rhythm or structural heart problem being hard to detect between episodes
- A blackout recurring before the cause is found, with risk of injury
Most blackouts are harmless faints, but a small number are caused by a heart problem that can be dangerous, so the heart deserves careful thought. Because some causes are intermittent, a normal assessment cannot always rule them out, and longer monitoring is sometimes needed. The history and a witness account are crucial. Ask whether a heart cause has been considered, what it means for driving, and what to do if you black out again.
Published figures to discuss
There is no single reliable figure for how often a blackout has a dangerous cause, because it depends heavily on age, heart history and exactly what happened. Most are simple faints; a minority are due to a heart rhythm problem. Because some heart causes are intermittent, tests on the day can be normal even when a problem exists, so monitoring over time and the history matter more than any one result. The aim is to identify the higher-risk group safely, not to give a fixed success rate.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Cardiac syncope missed | High-risk if exertional, supine or with palpitations | NICE TLoC guidance separates simple faint from features needing urgent cardiac assessment. | NICE CG109 — Transient loss of consciousness ('blackouts')nice.org.ukSource-linked context |
| Seizure mistaken for faint | Recognised diagnostic overlap | Tongue biting, prolonged confusion, witnessed rhythmic jerking or no prodrome can change the pathway. | Guide sourcesClinical context |
| Injury from collapse | Event-dependent | Head injury, anticoagulants, pregnancy or severe trauma needs urgent assessment. | NHS — Faintingnhs.ukSource-linked context |
| Driving restriction not discussed | Safety/legal issue | Blackouts can trigger DVLA (or DVA in Northern Ireland) restrictions depending on cause and recurrence risk. | NHS — Faintingnhs.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no physical recovery from the assessment itself. What matters afterwards is understanding the likely cause, following any monitoring or driving advice, and knowing the danger signs that mean you should seek emergency help.
- Feeling tired or shaken for a short time after the blackout
- Mild bruising where blood was taken
- Waiting for a heart monitor result, which may take days or longer
- Temporary advice not to drive until the cause is clear
Aftercare
- Follow any advice about not driving, and tell the driver licensing authority if you are told you need to (the DVLA in England, Scotland and Wales, or the DVA in Northern Ireland).
- Wear any heart monitor as instructed and keep a diary of symptoms while you have it.
- Take medicines as prescribed and ask whether any could have contributed to the blackout.
- Stand up slowly and stay well hydrated if a simple faint or a drop in blood pressure was the cause.
- Know the danger signs that mean you should call 999, and do not delay.
- Make sure you know who to contact, and how, if you black out again before follow-up.
- Avoid situations where a sudden blackout could be dangerous (heights, swimming alone, machinery) until you have advice.
- A written account of exactly what happened
- A witness account if anyone saw it
- A full list of your medicines
- Notes on any heart symptoms and family history
- Whether you drive or operate machinery, noted for the clinician
- Details of any previous blackouts or seizures
- Questions written down and a way to record your result and plan
⚠ Get urgent help if…
- Someone cannot be woken within a minute — call 999
- Jerking, shaking, stiffening or other signs of a fit — call 999
- A blackout that happened during exercise or exertion — seek urgent help
- A blackout with chest pain, palpitations or breathlessness — call 999
- A head injury during the collapse, especially with drowsiness, vomiting or confusion — seek urgent help
- Repeated blackouts, or a blackout with no warning at all — seek urgent advice
- A first blackout in someone with known heart disease or a family history of sudden death — treat as urgent
- Weakness, slurred speech or face drooping after a collapse — call 999 (possible stroke)
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good result is a clear understanding of why you blacked out and whether it is dangerous. For most people the answer is a simple faint — for example from standing too long, the sight of blood, pain, heat or a drop in blood pressure on standing — which is not dangerous and can often be managed with simple measures.
The limits are important. Some causes, especially heart rhythm problems, come and go, so a normal heart tracing on the day does not always rule them out. This is why doctors may use longer monitoring and why you should report any further blackouts. A normal assessment reduces, but cannot completely remove, the chance of it happening again.
The result reflects what was found at the time. If you black out again, or develop new heart symptoms, it needs assessing afresh — an earlier normal result does not guarantee the future. Where a cause such as low blood pressure on standing or a medicine is found, managing it can reduce future episodes.
Related tests, treatments or support
A blackout work-up often combines the history and witness account with an ECG, blood tests, lying-and-standing blood pressure, and sometimes an echocardiogram or a period of heart monitoring. If a fit is suspected, neurology tests such as a brain scan or EEG may be added. Your clinician should explain why each is chosen.
Follow-up & long-term care
How you get your results depends on the setting. You should leave knowing which tests are still outstanding (such as a heart monitor), when and how you will get them, who will act on them, the driving advice, and what to do if you black out again. If you were referred to a heart specialist or neurologist, check the appointment is booked.
- Follow any driving rules and notification advice you are given — the DVLA covers England, Scotland and Wales, and the DVA covers Northern Ireland.
- Manage any cause that was found, such as adjusting medicines or improving hydration, with your clinician.
- Attend any follow-up monitoring or specialist appointments.
- Keep a record of any further blackouts, including warning signs and what you were doing.
Repeat, follow-on and what comes next
- A normal heart tracing on the day does not rule out an intermittent rhythm problem, so longer monitoring is sometimes needed.
- An inconclusive assessment may lead to a heart monitor, an echocardiogram or neurology tests over the following days or weeks.
- If you black out again, the whole picture should be re-assessed rather than relying on an earlier normal result.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Clear written advice on the symptoms that mean you should call 999 again.
- Honest advice about driving and any notification to the DVLA (or the DVA in Northern Ireland).
- A named way to get monitoring results and to be seen again if needed.
- A plan for any cause found, shared with your GP.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- How urgently you are seen and whether the assessment is in a same-day unit or an outpatient clinic
- Which clinician assesses you (acute physician, general physician, heart specialist or neurologist)
- How many blood tests are needed
- Whether you need an ECG, echocardiogram, heart monitor, brain scan or EEG
- How long any heart monitoring lasts and whether a specialist reports it
- Any follow-up appointment, further tests or onward referral
- The clinician's assessment fee and which specialty they are from
- The cost of blood tests and an ECG
- The cost of any echocardiogram, heart monitor, brain scan or EEG, and reporting
- How long heart monitoring is included for, and the cost of longer monitoring
- What happens, and what it costs, if you need further tests or admission
- Any follow-up appointment and how results are communicated
- The cancellation policy and what happens if a complication occurs
On the NHS? Blackouts are assessed on the NHS through 999, A&E, acute medical units and syncope clinics when clinically indicated; private same-day assessment is mainly used for speed, choice or a second opinion in recovered, stable patients, never as a substitute for emergency care.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- A heart cause not being considered, or a normal ECG being treated as a complete all-clear.
- No clear advice about driving and notifying the DVLA (or the DVA in Northern Ireland).
- No witness account being sought when one is available.
- Being steered into a private booking when the event actually needs emergency assessment.
- No written safety-net advice on what to do if it happens again.
Marketing red flags
- Any service that assesses blackouts instead of telling you to call 999 for danger signs.
- Claims that one test gives a complete answer for why someone blacked out.
- Heart screening packages sold on fear without explaining limitations and intermittent causes.
- Same-day private appointments promoted as a substitute for emergency care.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Do you think this was a simple faint, a fit, or a heart problem — and why?
- Has a heart rhythm cause been considered, and do I need a monitor or echocardiogram?
- What does this mean for my driving, and do I need to tell the DVLA (or the DVA in Northern Ireland)?
- What should I do, and who should I call, if I black out again?
- Which results are still outstanding, and how and when will I get them?
- Are any of my medicines likely to have contributed?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my test, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this test not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
When is a blackout an emergency rather than something to book about?
Most faints are harmless — why do I need any assessment?
Why is what a witness saw so important?
Can I drive after a blackout?
Why might I need to wear a heart monitor?
Is this assessment available on the NHS?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Fainting NHS — When to call 999 NICE CG109 — Transient loss of consciousness ('blackouts') British Heart Foundation — When to seek urgent help Society for Acute Medicine — Same Day Emergency Care nidirect — Urgent and emergency care services (NI) nidirect — GP out-of-hours service (NI) DVLA — Assessing fitness to drive DVA Northern Ireland — Tell the DVA about a driver medical condition
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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