Fainting
Fainting is a brief loss of consciousness caused by the brain going short of blood flow for a few seconds.
On this page
- What happens in those few seconds
- The warning signs: half a minute that decides a lot
- The common faint: stuffy rooms, long queues, the sight of blood
- When the cause is the heart, and why that is a different conversation
- What to do if you feel yourself going
- If someone collapses beside you
- When to call an ambulance
- What happens at the appointment
- Online consultation
Fainting is a brief loss of consciousness caused by the brain going short of blood flow for a few seconds. The person turns pale, sinks to the ground, lies still for perhaps half a minute and then comes round on their own: no medicines, no help from anyone, and usually with a clear head straight afterwards. Roughly one person in three faints at some point in life, and most of the time nothing dangerous lies behind it. Not always, though. What separates a harmless faint from a dangerous one is not how frightening it looked to the people watching, but a handful of details: whether there was any warning, what the person was doing at that moment, what position they were in, and what is known about their heart and their family. Working through those details matters far more than taking a blood pressure reading the next morning.
What happens in those few seconds
The brain stores almost no oxygen and lives on whatever the blood delivers right now. Let blood pressure or the output of the heart drop for a few seconds and consciousness switches off. In a sense it switches off protectively: the person falls, the body ends up horizontal, blood no longer has to climb to the head against gravity, flow returns and consciousness comes back. The fall is part of the recovery, not only an injury. That is why a faint is short; if someone is unconscious for more than a minute or two, this is no longer a faint and it needs looking at differently.
One detail alarms bystanders more than any other. In the last seconds some people twitch their arms and legs, their eyes roll back, occasionally they wet themselves. This is not necessarily an epileptic seizure: an ordinary faint with a deep drop in pressure looks exactly like this. Epilepsy is suggested by other things — a bitten tongue at the side, confusion and drowsiness lasting many minutes afterwards, an odd smell or a sense of déjà vu beforehand. After a faint, by contrast, the person is oriented almost at once.
The warning signs: half a minute that decides a lot
Most faints announce themselves. Over ten to thirty seconds a familiar set of sensations builds up, and people describe it in much the same words:
- light-headedness, a sense of the floor sliding away, "I'm going down";
- vision darkening or narrowing to a tunnel, colours draining out of it;
- ringing or roaring in the ears, voices around you turning muffled and distant;
- cold clammy sweat, especially on the face and neck;
- nausea, sometimes an urge to open the bowels;
- sudden pallor, yawning, legs going weak.
Those seconds are worth remembering, and here is why. Having warning signs is an argument that the faint was harmless. Having none is an argument that it was not. When somebody drops instantly, with no time to feel anything and no time to grab hold of something, and wakes up with a damaged face because their hands never came out to break the fall, that is precisely the pattern a doctor needs to see without delay.
The common faint: stuffy rooms, long queues, the sight of blood
More than half of all faints are vasovagal. The body answers a strong stimulus in the wrong way: blood vessels widen, the pulse slows, pressure collapses. The setting is usually recognisable:
- standing still for a long time — in a queue, on public transport, at a ceremony, at a church service;
- a hot stuffy room, a sauna, a packed carriage;
- the sight of blood, an injection, having blood taken, even a conversation about medical procedures;
- severe pain, fright, bad news;
- straining: a hard bout of coughing, lifting something heavy, passing urine at night in men, a difficult bowel movement.
Alongside it sits the other common type, the orthostatic faint: the person stood up sharply from bed or from the table and pressure failed to catch up. It is helped along by dehydration in hot weather, a skipped meal, recent vomiting or diarrhoea, alcohol, pregnancy — and very often by medicines. Diuretics, blood pressure drugs, alpha blockers used for an enlarged prostate, nitrates, some antidepressants and some allergy remedies lower pressure in their own right, and a faint can be the first signal that the dose needs reviewing. Never stop prescribed treatment on your own — bring your doctor everything you take, including anything bought over the counter.
When the cause is the heart, and why that is a different conversation
Cardiac fainting is a good deal less common than the vasovagal kind, but it is the one that can be a forerunner of sudden death. The cause is a disturbance of rhythm or an obstruction to flow inside the heart itself: the supply to the brain is cut off all at once rather than gradually. The features that point at the heart are these:
- a faint with no warning at all, as if the lights were switched off, falling flat and injuring the face;
- a faint during exertion — while running, climbing, swimming. Feeling faint after exercise happens to healthy people too, but losing consciousness during the effort itself is the heart until proven otherwise;
- a faint while lying down or sitting: the vasovagal mechanism barely works in that position, it needs you upright;
- a faint preceded by palpitations — abrupt skipped beats, thumping, a feeling that the heart has suddenly raced away;
- a faint together with chest pain or breathlessness;
- a faint in someone with a known valve problem, cardiomyopathy, a previous heart attack or heart failure;
- sudden death or unexplained drowning in close relatives at a young age, and cases where a family member fainted in the same way and later died suddenly.
The last point is the one most often lost, and it carries the most weight: inherited disorders of heart rhythm can stay silent for years, and a faint in a teenager is sometimes the only warning given. Volunteer this to the doctor even if you are not asked.
What to do if you feel yourself going
There is one rule: get low as fast as you can, before you are put there.
- Lie down where you are and get your legs up high — against a wall, on a chair, in someone's hands. A shop floor looks awkward; the pavement after a fall looks worse.
- If there is nowhere to lie, crouch down or sit straight on the floor. Sitting on a chair or a bench is a poor substitute: your head stays high, and that is the height you will fall from.
- Do not try to reach the toilet, the window or the fresh air outside. Most of the serious injuries from fainting happen during those few steps.
- While you are still on your feet, tensing muscles helps: cross your legs and squeeze your thighs hard, lock your hands together and pull them apart, clench your fists. This lifts pressure for a minute and sometimes aborts the episode.
- Call out to somebody. Even a brief "I feel awful, I'm going to fall" changes everything: there will be a person beside you to take your weight and keep your head off the ground.
- When it passes, stay down a few more minutes and get up slowly in two stages — sit first, then stand. Have some water.
If someone collapses beside you
There is not much to do, and nearly all of it amounts to staying out of the way.
- Lay them on their back and raise their legs about a third of a metre, holding them there. This returns blood to the head faster than anything you could wave under their nose.
- Do not sit them up and do not lift them, do not drag them outside and do not try to stand them on their feet until they have come round completely. Being upright is exactly what caused the faint; putting them back there prolongs it.
- Loosen the collar and the belt, open a window, ask people to stand back.
- Check whether they are breathing and whether the breathing is normal. If there is none, or it is slow, noisy and gasping, call an ambulance and start chest compressions rather than spending time trying to wake them.
- If they are breathing but not coming round, and also if they are vomiting or pregnant, turn them onto their side.
- Do not pour water into their mouth and give nothing to eat or drink until consciousness has fully returned.
- Once they are awake, let them stay down a few minutes longer: getting up too quickly often ends in a second faint.
When to call an ambulance
Call an ambulance — 112 is the single emergency number across Europe — if, after losing consciousness, the person:
- is not breathing or is breathing abnormally, or does not come round within a minute;
- has woken but stays confused, does not recognise family, slurs their words, cannot move an arm or a leg;
- complains of chest pain, severe breathlessness or marked irregularity of the heartbeat;
- collapsed during physical exertion, or lost consciousness while lying down;
- has been badly hurt, particularly a head injury, or takes blood-thinning medication;
- shook or jerked for longer than a few seconds;
- is pregnant, or has abdominal or back pain, black stools or vomited blood — fainting can be a sign of internal bleeding.
See a doctor the same day, without waiting for a routine appointment, after a first-ever faint with no clear explanation, after repeated faints, after a faint with no warning signs, if you have known heart disease, or if young relatives have died suddenly. Otherwise book an ordinary appointment: even a harmless faint deserves to be looked at properly once.
What happens at the appointment
The main instrument here is a detailed account, not a machine. The doctor will ask meticulously: what you were doing at the time, whether you were standing or sitting, what you felt beforehand, how long you were down, what you remember afterwards, whether there was jerking or a bitten tongue. A witness to the episode is worth more than any test — if someone can come with you, or at least write down what they saw, bring that.
After that, an electrocardiogram is almost always recorded and blood pressure measured lying down and again after a few minutes standing; blood is taken, above all so that anaemia is not missed. If the picture points at the heart, a twenty-four-hour or longer recording of the rhythm is added, along with an ultrasound scan of the heart and sometimes an exercise test. Driving and any work where losing consciousness would be dangerous are discussed separately: the restrictions depend on the cause and on the country, and it is the doctor who decides them, not the person themselves.
Online consultation
Fainting is unpicked in words, which is why remote care suits it better than it suits many other complaints. The doctor will rebuild the circumstances of the episode through questions you would never have put to yourself, and that alone often separates a vasovagal faint from a cardiac one; will tell a faint apart from a seizure and from ordinary dizziness; will go through your list of medicines looking for the ones that drop your pressure; will ask about sudden deaths in the family; will explain which investigations are worth doing and in what order, and help you read results you already have. There is a further benefit: learning to recognise the warning signs and abort an episode, so that a faint does not end in a fracture.
The limits of the format are obvious: nobody can record your heart tracing through a screen, measure your standing blood pressure or listen to your heart. And most important of all — during the episode itself and immediately afterwards you need an ambulance or a face-to-face examination, not a message thread.
This material is for information only and does not replace medical advice.
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