Fortunately, you cannot be allergic to your cell phone per se. However, you can be allergic to metallic parts/cases of cell phones. Metals such as nickel, cobalt, and chromium are all possible causes of an allergic skin rash (called allergic contact dermatitis) from cell phone usage. A preliminary study in 2012 by Mucci and colleagues, reported at the 2012 ACAAI Annual Meeting, found nickel and cobalt in the highest concentrations in used cell phones, while an earlier study did not find high levels of nickel and cobalt in new cell phones. The higher levels in the used phones are probably due to wearing of the plastic coating on metal keys/parts occurring over time. Models that operate without keys, including the iPhone and Motorola Droid, both tested negative (keep in mind after-market cases may contain metal, however).Cellular phone dermatitis typically starts as an itchy rash on the side of the face where the phone is touched to the head, especially around the ear. People with this problem do not always report a history of known allergic reactions to metals. Allergic contact dermatitis is diagnosed based on the history and the results of patch testing to metal(s), which can be performed by your allergist. There are also several nickel and cobalt spot test kits available that allow one to test various objects for the release of nickel or cobalt ions.