A defibrillator is a device that uses electricity to re-start your heart. The electricity can shock your heart back into its normal heartbeat pattern. They are sometimes called a 'defib'.
The defibrillator checks your heartbeat pattern to decide whether an electric shock is needed.
There are different types of defibrillators that work in different ways.
Automated external defibrillators (AEDs) are found in public places. They can be used by anybody in an emergency. They guide you through each step of the process.
Some types of AED ask you to press a button to deliver the shock. Other types give the electric shock automatically.
If your heart is beating normally, you don't need an electric shock. The AED will check this. It won't give an electric shock unless it's necessary. You can't hurt someone by using an AED.
Implantable cardioverter defibrillators (ICDs) are defibrillators that are put inside your body. You need an operation to put the ICD into your body.
ICDs are used in people who have a high chance of having a heart rhythm problem (heart arrhythmia). If this happens, your life can be at risk.
Wearable cardioverter defibrillators (WCDs) rest on your body. They are usually used by people who are:
A cardiac arrest is when your heart suddenly stops beating. When the heart stops beating, there is no blood going to your brain and other organs. You will die if blood does not get to your brain within 10 minutes.
A cardiac arrest is not the same as a heart attack, but both are emergencies. Signs that someone is having a cardiac arrest are:
If you need to give someone first aid, follow the DRSABCD action plan. Defibrillation is the last step in this action plan.
Defibrillators are used when someone has a cardiac arrest. This happens when the heart suddenly stops pumping blood properly.
Defibrillators should be used alongside cardiopulmonary resuscitation (CPR). CPR is a mixture of chest compressions and mouth-to-mouth breathing. This is done in an emergency to help keep a person alive.
Each year, more than 25,000 Australians have a cardiac arrest outside of hospital. Less than 1 in 10 people survive if a cardiac arrest outside of hospital.
Giving CPR and using an AED as soon as possible can help the person stay alive. The most important thing is to use the AED quickly. Time is really important.
AEDs are often found in public places, such as:
In indoor spaces, defibrillators are often found in the foyer or reception area. They will be clearly visible.
The Heart of the Nation app (Opens in new tab) can help you find defibrillators in Australia.
The AED machine will verbally tell you what to do. It will usually come with images or pictures to guide you.
Anyone can use an AED. AEDs must be used along with CPR.
See the video below to familiarise yourself with how to use an AED.
The steps are similar to those on the list below.
You can buy an AED for your home, work or organisation. If you want to buy an AED, be sure to:
Place the AED where it can easily be seen. It needs to be somewhere that everyone can get to.
It should not be locked away or in a cupboard. Make sure people know where it is. It's a good idea to train people how to use it.
Be sure to regularly check the AED. You need to maintain it. Follow the manufacturer's instructions so it's ready to use at any time.
You don't need training to use an AED, but first aid training may increase your confidence.
To find a first aid training course near you, contact:
You can view defibrillators for sale on the St John Ambulance (Opens in new tab) website.
You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.
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Last reviewed: March 2025
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