When placing AED pads on an adult, one pad goes on the upper right chest just below the collarbone, and the other goes on the lower left side of the chest beneath the nipple line. This standard positioning sends the electrical current directly through the heart, giving the shock the best chance of restoring a normal rhythm. Getting it right matters, but it’s simpler than most people expect.
Standard Pad Placement
The standard layout is called anterolateral, meaning front-and-side. The first pad goes to the right of the breastbone, just below the collarbone. The second pad goes on the left side of the chest, just below and to the left of the left nipple, along the side of the torso. On a male patient, this second pad lines up with the bottom edge of the chest muscle. On a female patient, it goes under the left breast.
This positioning creates an electrical path that crosses the heart between the two pads. The AED analyzes the heart’s rhythm and, if it detects a life-threatening pattern like ventricular fibrillation, delivers a shock along that path to reset the heart’s electrical activity. The 2025 American Heart Association guidelines emphasize that optimized pad placement is an important factor in whether a shock succeeds.
Nearly every AED includes a diagram on the pads themselves or on the packaging showing exactly where each one goes. Follow that diagram. The pads are typically labeled or color-coded so you can’t easily mix them up.
Preparing the Chest
The pads need full, direct contact with bare skin. Before placing them, you’ll need to address a few things quickly.
- Clothing: Remove or cut away any shirt, bra, or undergarment covering the chest. The pads cannot go over fabric or dressings.
- Moisture: If the person’s chest is wet from sweat, rain, or submersion in water, dry it thoroughly with a towel, shirt, or any absorbent material you have. Dry the ribs, upper stomach, neck, and armpits as well. Even a small amount of water can prevent the pads from sticking and can scatter the electrical current away from the heart, reducing the shock’s effectiveness.
- Chest hair: Dense chest hair can trap air under the pads, blocking contact with the skin. Many AED kits include a razor for this reason. If one is available, quickly shave the areas where the pads will go. If no razor is available, press the pads down as firmly as you can.
- Medication patches: If you see a transdermal patch (nicotine, pain medication, or hormone patches) in the area where a pad needs to go, peel it off and wipe the skin before placing the pad. The patch can block the electrical current or cause a burn.
Speed matters more than perfection here. You’re preparing the chest to improve contact, but don’t spend minutes on it. A few seconds of wiping and clearing is enough to make a meaningful difference.
Placement Around Implanted Devices
Some adults have an implanted pacemaker or defibrillator, visible as a small, hard lump under the skin of the upper chest, usually just below the collarbone. If the device sits directly where you’d normally place a pad, shift the pad so it’s at least 1 inch (2.5 cm) away from the device. Placing a pad directly over the implant can damage the device and may reduce how effectively the shock reaches the heart.
Placement for Larger Breasts
The left pad needs to make contact with the skin of the chest wall, not sit on top of breast tissue. For someone with larger breasts, lift the left breast and place the pad on the skin underneath it, along the lower left ribcage. The goal is firm adhesion to the chest wall so the current travels through the torso rather than across the surface of the skin. The upper right pad placement typically isn’t affected.
The Alternative: Front-and-Back Placement
If the standard side-by-side position isn’t practical, there’s an alternative called anteroposterior placement. One pad goes on the left side of the front chest, and the other goes on the upper left back, just below the shoulder blade. This sends the current through the heart from front to back instead of side to side.
The AHA recommends the standard anterolateral position for ease of placement but notes that anteroposterior is an acceptable alternative based on individual patient characteristics. It can be useful when breast tissue, body habitus, or an implanted device makes the standard position difficult. If you use this approach, you’ll need to partially roll the person to place the back pad, then roll them flat again before the AED delivers a shock.
Water and Wet Environments
If someone has been pulled from a pool, lake, or any body of water, move them to a dry surface before using the AED. Standing water near the person during a shock poses an electrocution risk to rescuers and bystanders. Once the person is on dry ground, remove wet clothing from the chest, dry the skin completely, then apply the pads. The pads will not adhere properly to wet skin, and water on the surface can divert the electrical current away from the heart.
Check the Pads Before You Need Them
AED pads have an expiration date printed on the packaging. Over time, the conductive gel on the pads dries out, which means they won’t stick properly and may not deliver an effective shock. If you’re responsible for maintaining an AED at a workplace, school, or public facility, check the pad expiration date regularly. Most pads last two to four years, but this varies by manufacturer. Replacing them on schedule is one of the simplest things you can do to make sure the device works when it’s needed.
Once the pads are placed and connected, the AED takes over. It will analyze the heart rhythm, tell you whether a shock is advised, and instruct you to press the shock button or to continue CPR. Your job during pad placement is to get good skin contact in the right locations, and the device handles the rest.