Before using an AED, you need to remove anything between the pads and bare skin that could block the electrical signal, cause burns, or prevent the pads from sticking. That means clothing, medication patches, excessive chest hair, jewelry near the pad site, and moisture all need to be addressed. The goal is clean, dry, bare skin so the pads make full contact and the shock reaches the heart effectively.
Clothing Over the Chest
The AED pads must be placed directly on bare skin, so any clothing covering the chest needs to come off or be cut away. T-shirts, jackets, sweaters, and undershirts should all be removed. Many AED kits include scissors or shears specifically for cutting through clothing quickly. Speed matters here: every second without a shock during cardiac arrest reduces the chance of survival, so don’t waste time trying to unbutton a shirt when you can cut straight through it.
Bras are a common concern, especially underwire bras with metal components. A 2025 review by the International Liaison Committee on Resuscitation found no documented cases of adverse events from defibrillation without removing a bra. In an animal study, researchers delivered 126 shocks through AED pads placed in direct contact with metal underwire, and reported no arcing, no burns, no redirection of current, and 100 percent first-shock success. The current guidance is that removing a bra may not always be necessary. If you can place the pads on bare skin in the correct position by simply adjusting the bra, that’s acceptable. If the bra is in the way, remove it, but don’t let it delay the shock.
Medication Patches
Transdermal medication patches (the adhesive patches that deliver drugs through the skin for pain relief, nicotine replacement, hormone therapy, or heart conditions) must be removed if they’re in the spot where an AED pad needs to go. Placing an AED pad directly over a medication patch can cause thermal burns when the shock is delivered. If you find a patch in the pad placement area, peel it off and wipe the skin to remove any residual medication or adhesive. Be careful not to get the medication on your own skin in the process. If the patch is on a part of the chest far from where the pads will sit, it’s not a concern.
Excessive Chest Hair
AED pads need to stick firmly to the skin to deliver a shock. Thick chest hair can trap air between the pad and the skin, weakening the electrical contact and potentially causing the AED to display a “check pads” error or fail to analyze the heart rhythm properly.
If the pads aren’t adhering because of excessive hair, St John Ambulance Australia recommends a quick approach: rip the first set of pads off briskly (this pulls out some of the hair), then clip the remaining hair with blunt-nosed shears before applying a fresh set of pads. Many AED kits include a razor for this reason. If you only have one set of pads, clip the hair first in the areas where the pads will go, then apply them. The key principle is to spend as little time as possible on this step. Don’t delay the shock for a perfectly smooth chest. Only address the hair if it’s genuinely preventing the pads from sticking.
Moisture and Water
A wet chest can cause the electrical current to spread across the skin surface rather than traveling through the chest to the heart. It can also prevent the pads from sticking. Before placing the pads, dry the chest thoroughly with a towel or cloth. This applies to sweat, rain, or any situation where the person was pulled from water. If the person is lying in a puddle, move them to a dry surface first. AEDs deliver a significant electrical charge, and standing water creates a safety risk for both the victim and the rescuer.
Jewelry and Body Piercings
Remove any metal jewelry or body piercings that could come in contact with the AED pads. This includes necklaces that drape across the chest and nipple piercings. Metal in the path of the electrical current can cause localized burns and may interfere with shock delivery. If a necklace can simply be moved aside or a piercing isn’t near the pad placement area, that’s fine. The concern is specifically about metal sitting between or directly under the pads.
Implanted Devices
You can’t remove a pacemaker or implanted defibrillator, but you need to know it’s there. These devices typically create a visible hard lump under the skin on the upper chest, usually below the collarbone. AED pads should be placed at least one inch away from the implanted device to avoid damaging it or interfering with the shock. Adjust the pad position slightly if needed, but don’t skip using the AED. A pacemaker is not a reason to withhold defibrillation.
What to Prioritize
In a real emergency, you won’t have time to methodically check for every item on this list. The most important priorities are removing clothing to expose bare skin and drying the chest if it’s wet. Those two steps apply to nearly every situation. Medication patches, excessive hair, and jewelry are things to notice and address quickly, but none of them should delay turning on the AED and following its voice prompts. The device itself will tell you if it can’t get a good reading, giving you a chance to check the pad contact and fix the problem. A shock delivered 30 seconds sooner is worth far more than perfectly prepared skin.