If you’ve ever hesitated to use an AED in an emergency, you’re not alone. Many Canadians worry about doing it wrong, accidentally harming the person or themselves.
The truth is that automated external defibrillators (AEDs) are built to be incredibly safe, even in the hands of a complete beginner. They’re designed to guide you through the process step-by-step using clear voice prompts.
Most importantly, they won’t deliver a shock unless it’s medically needed. That means you can’t make a mistake that would hurt someone.
So if you ever face a cardiac emergency, don’t worry about the dangers of using a defibrillator. Trust it, and trust yourself. You could save someone’s life.
Originally published on January 11th, 2024, this article was updated and republished on May 21st, 2025.
The Reasons Defibrillators Are So Safe to Use
You don’t need to worry about the dangers of using a defibrillator or delivering a shock by mistake because the AED does all the hard thinking for you. These devices are safe, easy to use, and designed to guide you through every step with clear voice prompts.
Once the pads are attached correctly, the device checks the heart’s rhythm. If a shock is needed, the AED will either deliver it automatically or prompt you to press a button, depending on the type of device.
Fully automatic AEDs deliver the shock on their own if needed. Semi-automatic AEDs offer an extra layer of control, allowing you to confirm that no one is touching the patient before pressing the shock button. This can offer peace of mind in busy or high-pressure situations.
In both cases, you’re supported every step of the way. And if a shock isn’t needed, the device simply won’t deliver one; you can’t shock someone who doesn’t need it.
The shock itself is controlled and precise. It’s meant to reset the heart and allow it to beat normally again. There are no major defibrillator shock side effects, and the risk to the person helping is extremely low, especially if you follow the AED’s prompts.
In Canada, an estimated 60,000 cardiac arrests occur outside of hospitals each year, with a survival rate of only about 10%. However, survival rates can nearly double if someone takes fast action, performs CPR, and uses an automated external defibrillator (AED).[1]
If you see the signs of cardiac arrest—sudden collapse, unresponsiveness, and no normal breathing—don’t hesitate to act. That’s exactly when an AED is needed.
When Should an AED Not Be Used?
While AEDs are designed to be safe and user-friendly, there are a few situations where you should pause and assess before using one.
Think of this as guidance for using the device effectively, not reasons to hesitate when you see the signs of a cardiac emergency. Below, we outline the rare cases where you shouldn’t use an AED or should take extra care to do so correctly.
1. When the Person is Conscious and Breathing Normally
If someone is awake, breathing normally, or has a steady pulse, they’re not in cardiac arrest. Using an AED in this situation won’t help and could cause unnecessary confusion. Even if the person feels unwell or has collapsed briefly, don’t use the AED unless they become unresponsive and stop breathing.
Instead, keep them calm, stay close, and monitor their condition until help arrives. Be ready to use the AED if their condition changes.
2. In a Wet or Conductive Environment
Wondering what you should do if you need to use an AED on someone who is submerged in water? First, get them out of the water and onto a dry, safe surface. Water conducts electricity, and trying to use an AED in a wet environment puts both you and the person at risk.
Dry their chest as best you can before applying the AED pads. If the ground is damp but not soaked, you can still use the AED. However, just make sure the pads stick firmly and there’s no standing water under or around them.
3. On a Child Under One Year Old (Infant)
According to the American Heart Association, standard AEDs can be safely used on children aged 8 and older.
For children between 1 and 8 years old, it’s recommended to use an AED with pediatric pads, which are designed to deliver a more appropriate shock for smaller bodies.
Infants under 1 year typically require a manual defibrillator operated by trained professionals for the safest care.
That said, if no manual defibrillator is available and the infant is in cardiac arrest, using an AED with pediatric pads may still be better than doing nothing at all.
Always follow the device’s voice prompts. If it doesn’t advise a shock, continue CPR until emergency help arrives.
4. When the AED Advises Not to Shock
If the AED says “No shock advised,” trust it. That means the person’s heart rhythm isn’t one that can be treated with defibrillation. This is normal in some cases, especially if the heart has stopped entirely or the person is not in a shockable rhythm.
Even though you won’t be delivering a shock, continue CPR. Keep going until emergency responders arrive or the AED advises a shock later on. The device will continue to monitor and guide you.
5. Over a Pacemaker or Implantable Defibrillator
Defibrillators and pacemakers may sound similar, but they’re different. Some people have pacemakers or implantable cardioverter defibrillators (ICDs) just under the skin, usually near the left collarbone. You can often feel or see a small lump where the device sits.
If you notice this, avoid placing AED pads directly over it. Instead, position the pads slightly lower or to the side of the implant. The AED will still work effectively, and you’ll avoid interfering with the implanted device.
Are There Any Long-Term Side Effects from Using a Defibrillator?
While AEDs are incredibly safe and life-saving, it’s natural to wonder if there are any long-term side effects after someone receives a shock. The answer is no for most people, especially when considering the alternative.
AEDs are used in moments when the heart has stopped or gone into a life-threatening rhythm. The dangers of not using a defibrillator far outweigh any short-term discomfort.
That said, some people may experience minor side effects after a successful defibrillation:
- Small skin burns or irritation where the pads were placed
- A sore chest, much like you’d expect after intense muscle strain
- In some cases, survivors report fatigue or muscle aches in the hours or days after the event
More rarely, neurological effects may occur depending on how long the brain was without oxygen before the AED was used.
This isn’t caused by the shock itself but by the cardiac arrest that came before it. The sooner defibrillation happens, the lower the risk of lasting damage. The odds of surviving with minimal neurological impairment decrease significantly with each minute of delay in defibrillation.[2]
And yes, there’s often an emotional side to all this, for the person who received the shock and those who stepped in to help. Surviving a cardiac arrest is a major event, and it's completely normal to need time and support to process it afterward.
Fortunately, AEDs give people a real chance to survive, recover, and keep living their lives.
Confidence Starts with the Right AED
When it comes to saving lives, preparation makes all the difference. Choosing the right AED—and the right partner to supply it—gives you the confidence to act when it matters most.
At AED Advantage, we don’t just sell defibrillators. We help schools, businesses, and communities build safer spaces with expert guidance, trusted brands, and ongoing support. Whether you need a single unit or a custom plan for multiple locations, our team is here to help every step of the way.
Check out our AED Buying Guide or contact our team to find the right solution for your needs and budget.
References
[1] Weisfeldt, M. L., Sitlani, C. M., Ornato, J. P., Rea, T., Aufderheide, T. P., Davis, D., Dreyer, J., Hess, E. P., Jui, J., Maloney, J., Sopko, G., Powell, J., Nichol, G., Morrison, L. J., & the ROC Investigators. (2010). Survival after application of automatic external defibrillators before arrival of the emergency medical system: Evaluation in the Resuscitation Outcomes Consortium population of 21 million. Journal of the American College of Cardiology, 55(16), 1713–1720. https://pmc.ncbi.nlm.nih.gov/articles/PMC3008654/
[2] Weisfeldt, M. L., Everson-Stewart, S., Sitlani, C., Rea, T., Aufderheide, T. P., Atkins, D. L., ... & Nichol, G. (2011). Time to defibrillation and survival after out-of-hospital cardiac arrest with shockable rhythms: retrospective cohort study. BMJ, 343, d5577. https://pubmed.ncbi.nlm.nih.gov/21872969/
