A faint is the brain running short of blood for a few seconds.
Most faints are harmless: a common faint after standing too long, in the heat, with pain, or at the sight of blood. A few are warnings from the heart and need urgent checks. The difference usually lies in what happened just before, and what came after.
In plain words.
A common faint comes after standing for long, in the heat, with pain or fear, at the sight of blood or a needle, or after passing urine or coughing hard. There is usually a warning: light-headedness, sweating, feeling sick, and greying or narrowing vision. Lying down, the person wakes within a minute and feels washed out for a while.
Standing up too quickly can bring on a faint when the BP drops on standing. This is more common with age, with BP tablets and water tablets, with diabetes, after loose motions or vomiting, and with alcohol.
A faint from the heart is the one to worry about. Its warning signs: fainting during exercise or effort, or while lying down; fainting with no warning at all; chest pain, breathlessness or a pounding heart just before; a known heart problem; or someone in the family who died suddenly when young. Fainting during effort or while lying down needs hospital now; the other warning signs need an ECG the same day, and often a hospital stay.
Not every collapse is a faint. A few jerks during a faint are common, but a fit usually brings longer jerking, a bitten tongue, and confusion for many minutes afterwards. Low sugar, a stroke, bleeding inside the body, and severe dehydration can also cause a collapse.
Why the lights go out
After standing long, in the heat, or with pain or fear, the blood vessels relax and the heart slows. Blood sinks into the legs, and the brain runs short for a few seconds. There is usually a warning first.
A heart rhythm problem can stop the pumping for a few seconds. It can strike with no warning, during effort, or even lying down. During effort or lying down, it needs hospital now; call 112 if it came during effort, or with chest pain, breathlessness or a pounding heart.
Lying flat with the legs raised brings blood back to the brain. After a common faint, a person wakes within a minute. If they do not, call 112.
Go to hospital now if
- The person does not wake within a minute, or is not breathing normally: call 112. If they are not breathing normally, start hands-only CPR, pushing hard and fast in the centre of the chest.
- Fainting with chest pain, breathlessness, or a racing, pounding or irregular heartbeat just before: call 112.
- Fainting during exercise or effort: call 112.
- Fainting while lying down, or in someone with heart failure or a past heart attack: go to hospital now.
- Fainting with a sudden severe headache, weakness of one side, slurred speech, or confusion that does not clear: call 112.
- Fainting with black stools, vomiting blood or heavy bleeding, or in pregnancy, or with severe tummy pain: go to hospital now.
- A head injury in the fall, especially in someone on blood thinners: go to hospital now.
- When someone faints: lay them flat on their back and raise their legs. If they vomit or are slow to wake, turn them onto their side. Do not sit them up, and give nothing to eat or drink until they are fully awake. Once awake, keep them lying down for a few minutes, then sit them up slowly.
Call 112 or go to the nearest emergency department. Ambulance: 108 (102 in some states).
See a doctor the same day, for an ECG, if
- The faint came with no warning at all
- You have any other known heart problem
- Someone in the family died suddenly, with no clear cause, before the age of 40
- You are older and have fainted for the first time, or faints keep happening
- You recently started or changed a BP, heart or water tablet
Tests that help.
Not everyone needs every test. He decides which ones are worth doing for you.
| Test | What it tells |
|---|---|
| ECG | Everyone who has fainted should have one. It looks for rhythm and heart muscle problems that can cause a dangerous faint. |
| Lying and standing BP | BP taken lying down, then after standing for up to three minutes, to catch a drop on standing. |
| Haemoglobin, sugar, sodium and kidney tests | Look for anaemia, a hidden bleed, sugar problems and dehydration. |
| Echo (ultrasound of the heart) | Shows the heart’s pumping and its valves, when a heart cause is possible. |
| Holter or a longer heart rhythm recording | Records the heartbeat for a day or more, to catch a rhythm problem that comes and goes. |
| Tilt-table test | Sometimes used to bring on a common faint safely, under supervision. |
Have it ready.
Tick them off as you gather them. The ticks stay on this phone only.
Online, or in person?
After a faint, do not drive, swim alone or work at a height until a doctor has checked the cause: after some kinds of faint, driving has to stop for a time. Do not stop BP or other medicines on your own.
A video call can
- Go through what happened, ideally with someone who saw it, to tell a common faint from a warning one
- Arrange an ECG, blood tests and heart rhythm recordings
- Review medicines that can drop the BP on standing
- Teach you how to prevent common faints and ride out the warning
Needs a visit in person
- A faint that has just happened with any sign in the red box: that is for hospital
- The ECG itself, and lying and standing BP
- Echo, Holter and tilt-table tests
- A pacemaker or other heart treatment, with a cardiologist
Talk it through with Dr. Arya.
Bring your reports and medicines to a video consultation. He goes through them with you, in plain words, and says clearly if you need to be seen in person.
Book a video consultationDr. Prabhat Arya · MBBS, MD (Internal Medicine) · Delhi Medical Council Reg. No. DMC-83759