COVID-19: Find information on how we’re keeping you safe here.

To top

What is fainting and what triggers this?

Vasovagal syncope, or more commonly known as fainting, is a condition that results in loss of consciousness which is usually transient without any prolonged complications, with rapid recovery and returned to normality afterwards. This condition is usually caused by low blood pressure or low heart rate or a combination of both. It is usually triggered by being in an upright position particularly when there are other factors involved which predispose one to fainting which can include: dehydration, heat, stress, and being stood up in a single position for a long time.

In most cases, fainting is preceded by feeling dizzy, or lightheaded, and may also be associated with palpitations, sweatiness, and nausea. Fainting can usually be aborted if one is able to respond to the early warning symptoms by sitting down or lying down whilst keeping the feet elevated.

Recurrent fainting is seen commonly in patients who have a low or low normal blood pressure and have previously experienced episodes of lightheadedness and dizziness particularly when standing for a long time or in the heat for example in school assembly or while standing in the queue or on public transport. It is important to learn to recognise the symptoms before the fate so that evasive action can be taken to avoid injury, which is more likely to occur when fainting happens from a standing position.

What are some top tips for reducing episodes of fainting?

  1. To ensure adequate hydration status at all times, but particularly before an event which is known to increase susceptibility to fainting success standing for a long time of being in a warm, hot and crowded environment.
  2. If you are resting blood pressure is low or low normal (typically under 120/80), then you can consider having more salt in your diet (typically 1 to 2 teaspoons extra)
  3. Learnt to take early base of action by recognising symptoms of pre-fainting, such as dizziness, loss, sweatiness, palpitations, and sitting down or squatting, and if possible, lying down with elevated feet to abort a faint
  4. Consider wearing compression stockings which should be worn from the toes or ankles, to the waist, which will help return blood that is starting to pool in the lower limbs during a faint.
  5. Rarely, if fainting continues and becomes a recurrent issue that affects your quality of life, it may be worth seeing a doctor who can pursue other strategies which includes carefully taking history and making an accurate diagnosis, as well as consideration of specific drugs that may be able to boost your blood pressure to minimise further episodes of fainting.

What are warning symptoms that should make me seek urgent medical attention?

Major red flag symptoms for fainting or syncope include fainting abruptly without any warning (unheralded syncope), or fainting with preceding rapid palpitations (a sensation of a fluttering rapid heartbeat), fainting during exercise, fainting resulting in injury, or fainting with a prolonged confusion state (>10 mins confusion after fainting). In these instances, you may need to seek urgent medical attention to rule out a significant non-benign cause of fainting.


Written by Dr Boon Lim, Consultant Cardiologist, specialising in heart rhythm disturbances including atrial fibrillation, pacing and syncope.