If you have a nickel allergy, there is not much to be worried about. Most of the bikini trimmers have been tested by dermatologists to ensure that they do not cause allergy when they come in contact with the skin. Nickel is used in the shaving foil of most bikini trimmers but it safe to you. Rest of the trimmer is made of steel, and holding it will not cause any allergy. To stay on the safe side, just consult your doctor about the allergy and trimmer usage.