Fainting: Why It Happens, First Aid and When Passing Out Is a Warning Sign

Fainting is frightening to watch, but most faints are harmless. Blood flow to the brain drops for a moment, the person falls, and they wake up within a minute or so. A small number of faints, though, are an early warning of a heart problem. Here’s how to tell the difference.

Imagine standing in a crowded, hot church at a wedding. The person next to you goes pale and sweaty, says they feel strange, and then crumples to the floor. Seconds later they open their eyes, confused and embarrassed. Was it the heat? Probably. But there are a few questions that every first aider should ask before saying “it was just a faint.”

Common causes of fainting

• Vasovagal syncope, the most common type: triggered by standing for a long time, heat, pain, fear, the sight of blood or needles
• Standing up too quickly, especially when dehydrated, after illness, or on blood pressure medicines
• Not eating or drinking enough, or drinking alcohol
• Heart rhythm problems or structural heart disease: less common, but important

Warning signs before a faint

Feeling light-headed, hot or sweaty, sick, yawning, blurred or “tunnel” vision, ringing in the ears, and looking very pale. If you feel these, lie down with your legs raised, or sit with your head between your knees, before you fall.

First aid when someone faints

1. Lay them on their back and raise their legs to help blood return to the brain.
2. Loosen tight clothing and give them fresh air.
3. They should come round within about a minute. Reassure them and help them sit up slowly.
4. If they don’t wake up quickly, check breathing. If they’re breathing, put them in the recovery position and call your emergency number. If they’re not breathing normally, call for help and start CPR.

But when is fainting a warning sign?

Call for emergency help or get urgent medical checks if the person:

• Fainted during exercise or while lying down
• Had chest pain, palpitations or breathlessness before or after
• Has a known heart condition, or a family history of sudden death under 40
• Fainted with no warning at all and was injured
• Took a long time to come round, had a seizure, or is still confused
• Is pregnant, older, or has fainted more than once

Anyone who has fainted for the first time should see a doctor or nurse, who will usually check blood pressure lying and standing and do an ECG (heart tracing). Check local driving rules too, as some types of faint affect your licence.

Sources: NHS (Fainting), NICE guideline on transient loss of consciousness, American Heart Association, Red Cross first aid guidance. This guide is for general information and does not replace advice from your own nurse, doctor or emergency services.