Fainting

Fainting is a sudden, temporary loss of consciousness that usually results in a fall.

Healthcare professionals often use the term "syncope" when referring to fainting, because it distinguishes fainting from other causes of temporary unconsciousness, such as seizures (fits) or concussion.

In most cases, when a person faints, they'll regain consciousness within a minute or two. However, less common types of fainting can be medical emergencies.

Dial 999 to request an ambulance if a person who has fainted doesn't regain consciousness within two minutes.

What causes a faint?

To function properly, the brain relies on oxygen that's carried in the blood. Fainting can occur when the blood flow to the brain is reduced.

Your body usually corrects reduced blood flow to the brain quickly, but it can make you feel odd, sweaty and dizzy. If it lasts long enough, you may faint.

Read more about the symptoms of fainting.

There are various reasons for a reduction in blood flow to the brain, but it's usually related to a temporary malfunction in the autonomic nervous system. This is the part of your nervous system that regulates the body's automatic functions, including heartbeat and blood pressure. This type of fainting is called "neurally mediated syncope".

Neurally mediated syncope can be triggered by emotional stress, pain or prolonged standing. It can also be caused by physical processes such as coughing, sneezing or laughing.

What to do if you or someone else faints

If you feel you're about to faint, lie down, preferably in a position where your head is low and your legs are raised. This will encourage blood flow to your brain.

If it's not possible to lie down, sit with your head between your knees. If you think someone is about to faint, you should help them to lie down or sit with their head between their knees.

If a person faints and doesn't regain consciousness within one or two minutes, put them into the recovery position.

To do this:

place them on their side so they're supported by one leg and one arm
open their airway by tilting their head back and lifting their chin
monitor their breathing and pulse continuously

You should then dial 999, ask for an ambulance and stay with the person until medical help arrives.

Treatment for fainting

In most cases, a person will return to normal within a few minutes of fainting, and no further treatment will be needed.

If a person experiences repeated episodes of fainting, it's important for a healthcare professional to investigate the cause.

Read more about the diagnosis of fainting.

Treatment for fainting will depend on the type you're experiencing. In many cases of neurally mediated syncope, no further treatment is needed.

If you've had a fainting episode, advice to deal with possible future fainting episodes includes:

avoiding triggers – such as hot and crowded environments, or emotional stress
spotting the warning signs – such as feeling lightheaded
lying down to increase blood flow to the brain

Read more about how fainting is treated.

Concussion
Mild, reversible brain damage, which can last a few seconds or a few hours, usually after a head injury.

Veins
Veins are a type of blood vessel. They carry blood back to the heart.