Health Details

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 of fainting, the person who has fainted regains consciousness within a minute or two.

But less common types of fainting can be medical emergencies. You should call 999 and request an ambulance if a person who has fainted does not regain consciousness within two minutes.

Why fainting happens

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

Reduced blood flow to the brain is usually quickly corrected, but it can cause people to feel odd, sweaty and dizzy. If it lasts long enough, they may fall down. This is called a faint. See symptoms of fainting for more information.

The reason for the reduced blood supply to the brain that causes fainting can vary. Usually, the cause is related to a temporary malfunction in the autonomic nervous system, which regulates many of the body's automatic functions, including heartbeat and maintenance of blood pressure. This kind of fainting is called neurally mediated syncope.

This kind of fainting can be triggered by emotional stress, pain, prolonged standing, and other experiences or circumstances. It can also be caused by physical processes such as coughing, sneezing, or laughing.

See causes of fainting for more information.

What you should do

If you know or suspect that you are going to faint, you should lie down, preferably in a position where your head is low and your legs are raised. This will encourage blood flow to the brain.

If it is not possible to lie down, sit down with your head between your knees.

If you suspect someone else is about to faint, you should help them to lie down or sit down in this way.

If a person faints and does not regain consciousness within one or two minutes, you should put them into the recovery position. To do this, you should:

• place the person on their side so they are 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 to request an ambulance and stay with the person until medical help arrives.

Treatment of fainting

In many cases of fainting you will return to normal within a few minutes, and no further treatment is needed.

In cases of repeated fainting and some other cases, is important that a healthcare professional investigates the cause of the fainting episode. See diagnosis of fainting for more information.

Treatment for fainting will depend on the kind of fainting you are experiencing.

In many cases of neurally mediated syncope, no further treatment is needed.

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

• avoiding the triggers for your fainting, such as hot and crowded environments, or emotional stress
• being prepared to spot the warning signs of fainting, such as feeling lightheaded, and lying down to increase blood flow to the brain

See treatment of fainting for more information.

Who is affected?

Fainting is very common. Around 50% of women will faint during their lives, and around 25% of men.

In 2008 to 2009, nearly 120,000 people in England were admitted to hospital for fainting. Almost half of these were 75 years of age or over.

Around a third of people who have fainted will faint again within three years. In general, the more someone faints, the more likely they are to faint again. 

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.