Consumer use of wearable health devices has been rapidly increasing. Because of prolonged skin contact required, allergic contact dermatitis to components has been reported. Eczematous rash is the most common dermatologic adverse reaction to continuous glucose monitors, and rash from wearable activity trackers is commonly reported by consumers, suggesting that allergic contact dermatitis to wearable health devices may be vastly underreported. Acrylates, methacrylates, and colophonium are the most common allergens found on patch testing. Isobornyl acrylate has been identified as the primary allergen in many cases of allergic contact dermatitis to continuous glucose monitors. These chemicals are found in either the adhesives or the units themselves. Awareness of the presence of these chemicals in wearable devices may provide assistance for diagnostic patch testing in users who have dermatological reactions to the devices and hopefully guide dermatotoxicological evaluation guidance by government and industry.