Miniaturized, handheld medical heating devices utilize an electrical heater formed from a self-limiting conductive material, such as a conductive polymer or ceramic. The material has an electrical resistance that gradually changes with temperature such that heat production from electrical current through the material varies the resistance. A thermally insulating jacket contains the self-limiting heater element, which can be coupled to an electrical power supply. In one embodiment, a probe thermally coupled to the heater extends outward from the jacket. In another embodiment, the self-limiting conductive material is in series with one electrode of an electrode pair (or three electrodes) adapted to deliver radio frequency energy to tissue.
