Should You Remove a Transdermal Patch Before Applying an AED?

Transdermal patches should be removed from a patient’s chest before AED pads are placed, and the skin underneath wiped clean. The reason is straightforward: many patches contain metallic components that can arc when high-energy electrical current passes through them, causing burns and potentially reducing the effectiveness of the shock. Every major resuscitation guideline agrees on this point, though the practical advice is more nuanced than simply “always rip off every patch first,” because speed matters enormously in cardiac arrest and the patch’s location relative to the AED pads is what determines the actual risk.

What Actually Happens When You Defibrillate Over a Patch

The core problem is electrical arcing. When a defibrillator delivers a shock, it sends a burst of energy between two pads (or paddles) placed on the chest. If a transdermal patch sits between or under one of those pads, and if that patch contains metal, the electrical current can arc through the metallic layer instead of traveling cleanly through the chest wall to the heart. The result is a small flash or even a minor explosion at the patch site, along with a burn on the skin beneath it.

This is not theoretical. Case reports dating back to the early 1990s document exactly this scenario. In two patients who were defibrillated with nitroglycerin skin patches in place, electrical arcing produced a visible flash of light and left thermal injuries on the skin.¹ Another case report described a small explosion when a defibrillator paddle was placed directly over a nitroglycerin patch, with the aluminum backing identified as the likely culprit.² The phenomenon is not limited to nitroglycerin. A patient with an implantable cardioverter-defibrillator (ICD) suffered skin burns in the shape of the aluminum foil layer inside a buprenorphine pain patch that had been placed directly over the device. The burns resolved in about two weeks, but the patch had been applied to that spot by a staff member who simply did not know about the risk.³

Beyond burns, there is a second concern. A patch sitting between the AED pad and the skin acts as a physical barrier. It can prevent the adhesive electrode from making full contact with the chest wall, which increases electrical impedance. Higher impedance means less of the defibrillator’s energy reaches the heart, potentially making the shock less effective at terminating a dangerous rhythm. Resuscitation guidance explicitly notes that a patch on the chest “may prevent good contact and may cause electrical arcing and burns.”⁴

The Metal Inside the Patch Is the Key Variable

Not every transdermal patch is equally dangerous during defibrillation. The risk comes specifically from metallic components embedded in the patch, and the type of backing material matters enormously. A controlled laboratory study tested nitroglycerin patches under defibrillator current and found a clear split: patches with a plastic backing caused no problems at all, while patches with a metal mesh backing consistently produced an explosive effect when the current flowed through the metallic layer.⁵ The distinction is the metal, not the drug.

This creates a practical problem, because you often cannot tell by looking at a patch whether it contains metal. A recent review of transdermal drug delivery systems found that roughly 60% of commercially available patches either contained metallic components or their presence could not be ruled out based on available information.⁶ Aluminum foil is the most common offender, used as a barrier layer to protect the drug reservoir from moisture and light. Some patches use aluminum-coated polyester. Others use entirely plastic construction. From the outside, they all look like a beige or clear adhesive square.

The drugs involved span a wide range. Nitroglycerin patches for angina were the first to be flagged because they were among the earliest widely used transdermal systems, but the risk applies to fentanyl patches for pain, nicotine patches for smoking cessation, estrogen patches for hormone therapy, buprenorphine patches for pain, clonidine patches for blood pressure, and others. Any patch with a metallic internal layer poses the same arcing hazard. The drug itself is irrelevant to the electrical danger; what matters is what the patch is made of.

Why Labeling Does Not Solve the Problem

You might expect that if a patch poses a defibrillation hazard, the product labeling would say so clearly. It usually does not. The same review that found metallic components in roughly 60% of patches also found that only about 14% of the corresponding product information documents mentioned the need to remove the patch before defibrillation or cardioversion.⁶ That means most patients wearing metal-containing patches have no warning on their medication packaging, and most healthcare providers applying these patches have no prompt to educate patients about the risk.

This labeling gap has real consequences. In the buprenorphine burn case, a junior nurse placed the analgesic patch directly over the patient’s implanted defibrillator because nobody on the team knew it was a problem.³ If the product labeling had flagged the hazard, that placement might have been avoided entirely. The situation is improving slowly as manufacturers reformulate patches with non-metallic barriers, but the transition is far from complete, and older formulations remain on the market.

What You Should Actually Do in an Emergency

The guidance from resuscitation organizations is consistent and practical. If you see a transdermal patch on the patient’s chest where an AED pad needs to go, peel it off, wipe the area with a cloth or your hand to remove any residual drug or adhesive, and then place the AED pad. The same advice applies to nitroglycerin ointment (a paste sometimes applied under a paper cover on the chest), which has also been associated with arcing when it creates a conductive bridge between electrode gel and defibrillator paddles.²

There is an alternative if removing the patch would take too long or is difficult: place the AED pads in a position that avoids the patch entirely. Standard AED pad placement puts one pad on the upper right chest below the collarbone and one on the lower left side of the ribcage. If the patch is on the upper right chest, you can shift the pad or use an anterior-posterior placement (one pad on the front of the chest, one on the back). Resuscitation guidance explicitly offers this as an option, stating that rescuers should “place the pads in an alternative position that avoids the patch or remove the patches and dry the skin area.”⁴

The critical point that gets lost in training courses is this: do not let patch removal significantly delay defibrillation. In cardiac arrest, every minute without a shock reduces the chance of survival. Peeling off a patch takes a few seconds. If you can do it quickly, do it. If the patch is stuck firmly, if your hands are gloved and slippery, or if you are fumbling with it while the AED is already charged and ready, move the pad to a different spot and shock. The burn risk from defibrillating over a patch is real but survivable. Delaying defibrillation is far more dangerous.

Patches That Are Not on the Chest

Most resuscitation guidance focuses on patches located on the chest, because that is where AED pads go and where arcing can occur. But transdermal patches are applied to all sorts of body locations: the upper arm, the back, the hip, the thigh, behind the ear (scopolamine patches for motion sickness). If a patch is on the patient’s arm or leg and nowhere near the AED pad placement sites, the arcing risk is essentially zero because the defibrillation current will not pass through that area. You do not need to hunt the patient’s entire body for patches before delivering a shock.

That said, a patch on the patient’s back could become relevant if you use anterior-posterior pad placement, and a patch on the upper chest or near the collarbone is directly in the standard pad zone. The practical rule is simple: check the areas where you are about to place the pads. If there is a patch there, remove it or work around it. Do not waste time searching elsewhere.

There is a separate medication-related concern that sometimes gets tangled up with the defibrillation question. Some rescuers worry about absorbing drugs through their own skin when handling a used fentanyl or nicotine patch. The actual risk of clinically significant absorption through intact skin from brief contact is extremely low, but wearing gloves is still a good practice for any medical care. The important thing is that this concern should never delay removing a patch from a cardiac arrest patient’s chest. Peel it off with gloved hands, wipe the area, and move on.

Patients with Implantable Defibrillators

The patch-plus-defibrillation issue takes on a slightly different character for patients who have an ICD, a small device implanted under the skin of the chest that automatically delivers shocks when it detects a dangerous heart rhythm. These patients do not get to choose when defibrillation happens; the device fires on its own. If a transdermal patch with a metallic layer is placed on the skin directly over the ICD generator, the device’s internal shock can arc through the patch’s metal just as an external defibrillator would.

The buprenorphine case illustrates this perfectly. The patient’s ICD fired multiple times to treat ventricular tachycardia, and each shock passed through the aluminum foil layer of the pain patch that had been applied right on top of the device. The result was a well-defined burn matching the foil’s shape.³ For patients with ICDs, the practical lesson is that no transdermal patch should be applied to the skin overlying the device. Nurses, pharmacists, and patients themselves need to know this, and as we have seen, the product labeling rarely helps.

Beyond burns, a patch over an ICD could theoretically alter the impedance pathway and reduce the effectiveness of the internal shock, although this has not been well studied. Given that a failed ICD shock in a patient with ventricular tachycardia or fibrillation is life-threatening, even a theoretical reduction in efficacy is worth avoiding.

How Patch Technology Is Changing

Patch manufacturers have been gradually moving away from metallic backing materials. The laboratory study that tested nitroglycerin patches found that plastic-backed versions caused no problems under defibrillation current, suggesting that reformulation could eliminate the arcing risk entirely.⁵ Many modern patches now use polymer films or non-metallic barrier layers to protect the drug reservoir. However, some drugs are more sensitive to moisture or light than others, and aluminum remains an effective and cheap barrier material. The transition away from metal is uneven across manufacturers and drug types.

For the rescuer, this means you cannot assume a patch is safe just because it is a newer product. Conversely, you cannot assume every patch is dangerous just because some contain metal. The safest approach in an emergency remains the same regardless of the patch’s age or brand: if it is under or near where the AED pad goes, remove it or move the pad. The few seconds this takes are well worth the assurance that you are delivering a clean shock.

Common Misconceptions About Patches and AEDs

One persistent myth is that the drug inside the patch is what makes defibrillation dangerous, as though nitroglycerin might somehow ignite. Nitroglycerin in patch form is a dilute formulation suspended in a gel or matrix. It is not the explosive compound used in demolition. The arcing and burning documented in case reports were caused by the metal in the patch construction, not by the medication.⁵ A nitroglycerin patch with an all-plastic construction would pose no more risk than bare skin. This matters because the misconception sometimes leads people to think only nitroglycerin patches are a problem, when in fact any metallic-backed patch carries the same hazard.

Another misconception is that removing a patch will cause a sudden dangerous loss of medication. Transdermal patches work by slowly releasing drug through the skin into the bloodstream over hours or days. Removing a fentanyl patch, for example, does not instantly eliminate the drug from the patient’s system. There is a reservoir of drug already absorbed into the skin layers beneath the patch, and blood levels decline gradually over many hours after removal. In a cardiac arrest, the patient’s medication schedule is the least of your concerns. Remove the patch without hesitation.

A third misunderstanding involves the role of moisture. Some training materials emphasize drying the chest before applying AED pads, which is good advice for ensuring adhesion and reducing impedance. But residual medication from a removed patch is a separate issue from water or sweat. Nitroglycerin ointment in particular is a greasy paste that can act as a conductive layer, and case reports have noted arcing in the presence of nitroglycerin ointment combined with electrode gel.² After removing any patch or wiping away any ointment, a quick wipe of the skin gives you a clean, dry surface for the AED pad.

What Rescuers and Patients Can Do Ahead of Time

If you wear a transdermal patch and also have a cardiac condition, or if you live with someone who does, there are a few simple precautions worth knowing. Apply patches to areas that are unlikely to be under AED pads: the upper arm, thigh, hip, or lower abdomen are all common application sites that stay clear of the standard pad zones on the upper right chest and lower left ribcage. If you have an ICD, never apply a patch directly over the device, and make sure anyone helping you with medications knows this.

For first responders and bystanders trained in AED use, the takeaway from three decades of case reports and guideline updates is simple and has not changed: look at the chest before you stick the pads on. If you see a patch, peel it off and wipe the spot. If peeling is taking too long, move the pad. Then deliver the shock. The risk from a patch is real but manageable. The risk from a delayed shock is not.