An inhaling device for use in inhaling an active powdered or liquid substance from a reservoir comprising a housing defining a dispersing chamber into which the active substance may be sucked in a dispersed condition, the dispersing chamber being defined by at least one wall part that is movable between first and second positions in which the chamber attains a minimum volume and a maximum volume, respectively, means for biasing the movable wall part toward the second position so as to suck active substance into the dispersing chamber from the reservoir, and a mouthpiece that enables a patient to inhale a dispersed active substance from the dispersing chamber.
