Apparatus is provided including an electrode device, adapted to be coupled to a site of a subject; and a control unit, adapted to drive the electrode device to apply a current to the site intermittently during alternating "on" and "off" periods, each of the "on" periods having an "on" duration equal to between 1 and 10 seconds, and each of the "off" periods having an "off" duration equal to at least 50% of the "on" duration. Other embodiments are also described.