Federal safety officials have told consumers across the United States to immediately stop using heated insoles sold under at least four brand names after the products’ lithium-ion batteries caught fire or exploded, in some cases causing second- and third-degree burns that required skin grafts. The U.S. Consumer Product Safety Commission has logged at least 51 reports of fires, explosions, or thermal incidents tied to COOWALK/COOWALI, iHeat, ZroeZroe, and Junsyoung heated insoles, all sold primarily through Amazon between 2022 and 2026. The batteries inside these devices can ignite even when the product is turned off, and the pattern of failures raises pointed questions about whether the physical design of battery-powered insoles makes them inherently prone to dangerous malfunctions.
Why battery fires in heated insoles keep happening
The CPSC has issued separate warnings for each of the four brands, and the common thread is striking. In every case, the agency identified the internal lithium-ion battery as the source of the hazard, stating that it can “explode and ignite” even when the insole is powered down. Approximately 6,000 COOWALK units were sold on Amazon.com and GearTrade.com from August 2022 through May 2026, and the agency is aware of 26 reports of fires, explosions, or thermal incidents involving those insoles alone.
The problem extends well beyond a single seller. The CPSC received 11 reports involving iHeat insoles, including eight burn injuries, some of them second- and third-degree. iHeat units were sold on Amazon from November 2022 to July 2024. ZroeZroe insoles, sold on Amazon and eBay, generated 10 reports of ignition or fire and at least four burn injuries, including burns severe enough to require skin grafts. Junsyoung insoles, manufactured by JunShengyoung of China and sold on Amazon under the Junsyoung name, account for another four incident reports, including at least one second-degree burn.
In all four cases, the insoles follow a similar blueprint: a thin lithium-ion battery encased in flexible material, wiring that runs through the insole to a heating element, and a small controller or switch to adjust temperature. That tight packaging allows the product to fit inside a shoe, but it also leaves very little margin for error. If a wire is pinched, insulation wears down, or the battery is compressed under body weight, the components can short-circuit and rapidly overheat. Because the batteries are sealed inside the insole, users have no practical way to inspect for damage or swelling before something goes wrong.
The risk is heightened by how the products are used. Heated insoles are designed to be walked on, bent, and flexed for hours at a time, often in cold or wet conditions that can stress electronics. Many consumers also use them inside tight boots or ski footwear that concentrate pressure on the footbed. That kind of repeated mechanical stress is exactly what lithium-ion cells are least tolerant of, especially when they are thin, low-cost packs without robust protective housings.
Unlike larger consumer electronics that must meet widely recognized testing standards, heated insoles occupy a gray area. They are wearable devices, but they are not medical products, and they are often sold directly by overseas manufacturers through online marketplaces with limited pre-market scrutiny. The CPSC warnings do not indicate that any of the four brands underwent independent certification for battery safety or for resistance to puncture and crushing. In practice, that means the first real stress test happens on customers’ feet.
What consumers are being told to do
In each of its notices, the CPSC has urged consumers to stop using the affected insoles immediately and to treat them as a live fire hazard even when they appear to be switched off. The agency advises owners to remove the insoles from footwear, avoid charging them, and store them away from flammable materials until they can be safely disposed of in accordance with local rules for lithium-ion batteries. Because the products were sold primarily online, there is no centralized recall program or in-store return option, and none of the warnings describe a refund or replacement process backed by the sellers.
The lack of a formal recall leaves many buyers in limbo. Some may never see the safety alerts if they do not regularly check CPSC announcements or the email account tied to their marketplace purchases. Others may assume that occasional warmth or a faint smell is normal for heated gear, not realizing that those can be early signs of a failing battery. The CPSC’s language underscores that this is not a minor defect: the reports include insoles bursting into flames on people’s feet and batteries igniting while the products were not in use.
What this means for battery-powered wearables
The cluster of incidents involving heated insoles highlights a broader challenge for battery-powered wearables that must be thin, flexible, and inexpensive. Designers are pushing lithium-ion cells into ever more constrained spaces, while online marketplaces make it easy for unvetted products to reach a global audience in a matter of weeks. Until safety standards catch up with these use cases, consumers may have to assume that any ultra-thin heated insole with a sealed battery carries some degree of risk, even if it has not yet been the subject of a public warning.
For now, the CPSC’s advice is straightforward: if you own heated insoles from COOWALK/COOWALI, iHeat, ZroeZroe, or Junsyoung, stop using them and dispose of them safely. And if you are considering battery-powered foot warmers of any brand, look for products with removable external batteries, visible safety certifications, and clear contact information for the manufacturer-features that can provide at least some assurance that warmth will not come at the cost of serious injury.
