A fluid dispenser device including a body and a reservoir, and an opening mechanism. The device includes an inhalation piece and an inhalation trigger system that has a deformable air chamber and a trigger element, such that during inhalation through the inhalation piece, the air chamber is deformed and the trigger element actuates the opening mechanism. The air chamber has a deformable side body; an open first end including a peripheral edge that surrounds an opening forming the inlet of the hollow pouch; and a second end forming the bottom of the hollow pouch. The said second end includes a connection mechanism for connecting the air chamber to the trigger element. The side body is in the form of a bellows having bellows portions arranged axially one after another, the bellows-forming side body has bellows portions having outside and/or inside diameters that are different.