General Health

Why do we faint?

Fainting can be a scary and confusing experience. Knowing why you may faint or how to respond when someone does can give you more confidence and reassurance to deal with it.

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Why do we faint?
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Fainting can be a scary and confusing experience. Knowing why you may faint or how to respond when someone does can give you more confidence and reassurance to deal with it.

What is fainting?

There are many reasons someone might faint, and it can happen to anyone at any age, although some are more at risk than others. 

The medical term for fainting is ‘syncope.’ Its origins come from the Greek word for 'cutting off' or 'contraction', reflecting the physiological changes that occur when someone faints. When blood flow is reduced or restricted to the brain, it can result in a person fainting.

What happens when you faint?

When the blood flow is restricted to the brain, the normal functions of the body can struggle. This leads the body to protect itself by prioritising blood flow to essential organs. When a person faints, they often end up horizontal on the floor, which allows blood to flow back to the brain. 

Whilst fainting is caused by many different factors, the biological response is most commonly activity in the vasovagal syncope. This nerve impacts many functions in the body. 

The vagal nerve stimulates the heart muscles, therefore controlling how fast or slow the heart beats. When the vagus nerve is stimulated in response to physical or emotional stress, it can signal the heart to slow down. This leads to a drop in blood pressure, meaning less blood is flowing to the brain.

Another reason why fainting occurs is when someone’s blood pressure suddenly drops. This happens when a person goes from sitting to standing very quickly. The blood flow is unable to reach the brain fast enough, therefore inducing a fainting episode.

Common reasons for fainting

There are many reasons why someone may faint: 

  • Fainting when standing up too quickly
  • Dehydration
  • Low blood sugar
  • Lack of sleep
  • Fatigue
  • Coughing too much
  • Exertion in high temperatures
  • Anxiety or fear
  • Seeing blood or something distressing

Fainting can appear to happen without an external stimulus. A person may not feel unwell before or after fainting. Typically, recovery from fainting is quick, with little to no after-effects.

Who is at risk of fainting?

Anyone is at risk of fainting, but some people in the population are more vulnerable to fainting:

  • Those with low blood pressure
  • Those with chronic illnesses
  • Those taking certain medications that slow the heart (e.g. beta blockers)
  • Those who experience seizures
  • The elderly

Reducing the risk of fainting

Fainting is rare, so it is not something to be actively worried around. But it is worthwhile being aware of risks and causes, and how to respond. You can undertake some basic precautions to reduce your chances of fainting:

  • Avoid standing up too quickly. Spend a few seconds moving your legs and arms to encourage blood flow to the rest of the body.
  • Undergo any medical procedures in a supine or lying position, such as injections or blood being taken.
  • If you begin to feel faint, try to sit down or lie down in a safe place and let others know.
  • Drink plenty of fluids and eat regularly to maintain hydration and blood sugar levels.
  • Check your medications for potential side-effects of fainting.
  • Maintain a healthy lifestyle with appropriate exercise.

If you are worried about your risks of fainting, speak to your GP or a healthcare professional.

What to do after you or someone has fainted

Fainting is unsettling and upsetting to experience. Wherever it happens, it is essential to follow some basic first aid advice to ensure a full recovery. 

Many people will come around from fainting very quickly. It is vital to ensure that you and they are safe. Speak to the person reassuringly throughout, telling them your name and what you are doing. 

If the person is lying down, lift their legs and support them with a rolled-up coat or cushions if those are to hand. Many people will come around after a couple of minutes. Help them to sit up slowly. Offering a hot, sweet drink afterwards can be reassuring and comforting.

If the person does not come around within a couple of minutes, you should check their airway and pulse. If they remain unresponsive, take steps to begin performing CPR and call 999.

If you or anyone has sustained injuries after fainting, call the emergency services or attend A&E. 

Look out for deep cuts or heavy bruising that may suggest an internal injury, and for head injuries.

When to seek further medical advice 

Many people may faint and recover with no lasting effects. The reasons for fainting can be something as simple as being too hot or standing up too quickly. Should seek medical advice when:

  • You are fainting very often
  • You faint at specific times or around specific triggers
  • You often feel faint or dizzy

Try to note down any symptoms you experience around any fainting episodes. This can be helpful when speaking to a medical professional.

Why do we faint?

Fainting can be frightening to experience or witness. Usually, people make a full and quick recovery from fainting. However, it is always worth investigating when the fainting is occurring within short periods of time. There are some basic steps you can take to reduce the risk of fainting, but it is always worth consulting a medical professional if you have any concerns.

The content on is provided for informational and educational purposes only and should not be construed as professional medical advice or guidance. Should you need professional medical advice or guidance, you should consult with such a professional in their relevant field. Likewise, you should always seek professional medical advice before starting a diet, exercise regime or course of medication, or introducing or eliminating specific elements from your lifestyle. We strive to write accurate, genuine and helpful content, and all views and opinions expressed within this article are specifically the views of the author.
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