About this symptom
Fainting is a short loss of consciousness, when you pass out for a few moments and then come round. Doctors call it syncope. It happens when not enough blood reaches the brain for a short time.
Most faints have a harmless cause, such as standing up too quickly, heat, not eating or drinking enough, or pain or strong emotion. But fainting can also be the first sign of a heart rhythm problem, so every faint should be checked.
Possible causes
This is not a diagnosis. These are the causes doctors think about, with the ones that are most urgent to rule out first.
- Heart rhythm problemFainting during exercise or while lying down, or with a pounding, fluttering or irregular heartbeat. Needs a heart check even if you recover quickly.
- Heart attackFainting with chest pain or pressure needs an ambulance at once.Read about it
- StrokeFainting with trouble speaking, vision problems or being unable to move an arm or leg.Read about it
- EpilepsyShaking or jerking of the body, a bitten tongue or loss of bladder or bowel control suggest a seizure rather than a simple faint.Read about it
- Low blood pressure on standingFainting soon after you stand up quickly, or after standing still for a long time. Some medicines can cause it.
- DehydrationNot drinking enough, being too hot or losing a lot of fluid can lower blood pressure and make a faint more likely.Read about it
- Simple faintBrought on by pain, strong emotion or heat, with warning signs first: dizziness, sweating, feeling hot, nausea or changes in vision.
- Side effect of a medicineFainting that began after starting a medicine, such as some for blood pressure, anxiety or depression. Do not stop it on your own; ask the doctor.
When to get help
Also get emergency care for:
- Trouble speaking, seeing or moving after the faint
- Fainting in someone who is pregnant, has diabetes or is over 50
- A fall from a height, or bleeding after the faint
- A bitten tongue, or loss of control of the bladder or bowel
Anyone who has fainted should see a doctor soon, even if they feel well again. Go sooner if:
- Fainting happens again, or you often feel as if you are about to faint
- You faint when you stand up, or soon after starting or changing a medicine
- You faint while coughing, passing urine or straining on the toilet
If you only felt faint and did not pass out, and it passed after you sat or lay down, it can wait for a routine visit.
What you can do at home
If any emergency sign is present, call for an ambulance first and follow any advice the operator gives.
Do
- If you feel faint, lie down and raise your legs, or sit and lower your head between your knees
- If someone faints, check that they are breathing, lay them on their back and raise their legs
- If the person is pregnant, especially after about 28 weeks, lay them on their side instead
- Loosen tight clothing and keep them lying until they feel better
- Get up slowly, drink enough water, and avoid standing still for a long time
Do not
- Do not stand or sit them up quickly
- Do not leave them alone until they are fully alert
- Do not drive them or yourself to hospital if an emergency sign is present: call for an ambulance
What the doctor will do
The doctor will ask what you were doing before, whether there were warning signs, how long you were out, and how you felt afterwards. They will ask about earlier faints and your medicines, and examine your heart, lungs and nerves. Your may be checked lying down and standing.
Tests depend on the likely cause. They may include:
- An , a recording of the heart's electrical activity
- Heart rhythm monitoring with a small recorder you wear
- An , an scan of the heart
- Blood tests, for anaemia or other causes
- An EEG, a recording of the brain's electrical activity, if a seizure is suspected
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“Splash water on the face, sit the person up or make them smell a shoe or an onion to bring them round.”What is true?
Fact
None of this is first aid. Check that they are breathing, lay them on their back and raise their legs. Most people come round quickly, and if they do not wake within a minute, call for an ambulance.
Myth“A faint that lasts a few seconds and passes is nothing to worry about.”What is true?
Fact
Most faints are not serious, but anyone who has fainted should see a doctor so the cause can be found. A heart rhythm problem can cause a faint that passes quickly.
Myth“Fainting is only weakness or low blood pressure, so a glucose drink and rest are enough.”What is true?
Fact
Low blood pressure and not eating or drinking enough explain many faints. But fainting can also come from the heart or from a seizure, so a doctor should check, especially if it happened during exercise or lying down, or came with chest pain or a pounding heartbeat.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
What should I do if someone faints in front of me?
Stay calm and ask loudly if they are all right. If they do not answer, call for help and check that they are breathing. If they are breathing normally, lay them on their back and raise their legs. Most people wake within a short time. If they are not breathing normally, call for an ambulance and start CPR if you know how. If they are breathing but do not wake within a minute, call for an ambulance too.
I fainted only once. Do I still need to see a doctor?
Yes. A single faint is usually not serious, but a doctor should check you so that the cause can be found, because a heart problem can be behind it. Go sooner if it happens again or you have chest pain or an irregular heartbeat.
Why do I faint when I stand up quickly?
When you stand up suddenly, blood pressure can drop for a moment and less blood reaches the brain. Not drinking enough and some medicines make this more likely. Getting up slowly and drinking enough water help. See a doctor if it keeps happening.
Is a faint the same as a seizure?
No. A faint is a drop in blood flow to the brain. A seizure comes from abnormal activity in the brain and may cause shaking or jerking, a bitten tongue or loss of control of the bladder. The doctor asks what happened, and may arrange tests such as an ECG or an EEG, to tell them apart.
