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Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 3 minutes read

A faint means a momentary loss of consciousness and is often referred to as a blackout. Doctors sometimes call it syncope or a vasovagal attack, and it’s very common, affecting up to 40% of people at least once in their lives. It usually first happens before the age of 40 (usually in the teens) and typically doesn’t have a serious cause although if it occurs for the first time after middle-age it can be a sign of an underlying health problem.

What are the common causes?

Fainting can occur if you get up too suddenly, or you’ve been standing for a long time, if you’re dehydrated, in hot weather, if you are fasting or you’ve skipped meals, if you suffer from low blood pressure or if you’re pregnant. You can look after yourself by keeping well-hydrated, especially during exercise or in hot climates, eating regular meals with long-lasting carbohydrates, and – if you know often feel dizzy when standing up – getting up slowly, especially from crouching or kneeling down.

Vasovagal syncope is when a major nerve called the vagal nerve is stimulated, and this is very common. This can occur during cervix dilatation via the vagina, such as a prolonged smear test or insertion of an intrauterine device (the copper coil or Mirena coil).

Alcohol and drugs can cause faints, and severe emotional distress, such as anger, upset or severe pain.

What are the symptoms of fainting?

Fainting usually occurs suddenly, although you may get warning signs just beforehand such as feeling light-headed, sweaty, hot and cold at the same time, or feeling sick. You will feel a bit groggy and often very tired when you come round, but quickly be able to tell who you are and where you are. This is different from a seizure which can last longer and which makes you jerk or twitch during it.

When should I worry?

More serious causes of faints occur in problems with the heart or nervous system. You should book an appointment with your doctor if you’re suffering repeated faints, if you fainted while exercising, or if you felt any sweating, shortness of breath or chest pain just prior to fainting. You should seek help if you are disorientated for a long time afterwards, or if there are symptoms to suggest a seizure such as tongue biting, urinary incontinence, or if someone has witnessed your arms or legs shaking.

How should I help someone who faints?

If someone faints, lie them down on their back somewhere safe and lift their legs onto a pillow or ledge, so the feet are at a higher level than their head. Make sure the environment is cool and encourage them to keep their breathing calm and regular. Reassure them that they are in a safe space. Offer sips of water when they have come round and are able to sit up. They should come round within 20 seconds or so.

Call for an ambulance if they haven’t come round after more than one minute, if they have a head injury or if there are any symptoms of a heart or nervous system cause, listed above.

Am I safe to drive?

Faints are common and you can drive if you’ve had one recent faint. You should seek the DVLA’s advice on driving if you have had repeated faints recently, and await your doctor's opinion and any test results.

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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