The present invention relates to a mercury dispensing system (11; 21, 31) for fluorescent lamps, comprising a dispensing member (12; 22, 32) containing a mercury releasing compound. The dispensing member (12; 22, 32) is fixed on a metal support (13; 23; 33) suitable to be heated by electromagnetic induction in order to cause the activation of said mercury releasing compound. The surface area of the metal support (13; 23; 33) is comprised between 9 and 64 mm2. The invention also relates to fluorescent lamps comprising said mercury dispensing system (11; 21; 31).