What is an AED, and how do I use it?

An automated external defibrillator (AED) is a small portable machine that reads the heart’s rhythm and, if needed, delivers a shock to restart it. It speaks instructions out loud, step by step, and is designed for someone with no medical training at all.

1. 1. Check and call 108

   Shout to check for a response. If the person is unresponsive and not breathing normally, call 108 straight away and put the phone on speaker.

2. 2. Start chest compressions

   Heel of one hand in the centre of the chest, other hand on top, arms straight. Push down about 5-6 cm, 100-120 times a minute. Push hard, let the chest come all the way back up, and don't stop.

3. 3. Send someone for the nearest AED

   While you keep pushing, send a second person to fetch the closest defibrillator. Use the map on this site to find it and get directions.

4. 4. Switch the AED on and follow it

   Open the lid and it starts talking. Stick the pads on the bare chest as pictured, let it analyse without anyone touching the person, and press the shock button when it tells you to. Then go straight back to compressions.

Watch how it’s done

Two short films from the British Heart Foundation. Click the play button to watch on the page.

Worth knowing

• An AED will not shock a heart that doesn't need it — it checks the rhythm first.
• You do not need training or permission to use one in an emergency.
• Survival falls by roughly 10% for every minute without defibrillation.
• Cut or shave nothing you don't have to; wipe a wet chest dry and avoid metal jewellery under the pads.

This page is general public-awareness information, not medical advice or a substitute for a certified CPR course.