Heat It dongle uses smartphone heat to ease insect bites

Heat It is a tiny smartphone-powered dongle that plugs into your phone (USB-C for Android and newer iPhones, Lightning for older iPhones) and fits on a keychain. After installing the app you heat the tip to a maximum of 124°F/51°C, press it onto the bite and follow the app timer; the app also offers adult and child modes, a sensitive-skin setting and short, medium and long application times, and it guides you through each step.

In testing on horsefly, mosquito, dog flea and other insect bites, the device reduced swelling and itchiness and outperformed over-the-counter creams and ointments. At the maximum setting the tip becomes mildly hot but not painful. The itch relief typically lasted a few hours, so particularly irritating bites sometimes needed multiple applications, and treating bites before bed helped prevent sleep-scratching.

Power consumption is modest—each application takes less than 0.1% of a smartphone battery—and the dongle requires no charging or use-by dates. It is available on Amazon for $30 for a limited time.