A fluid dispenser device including a main body (10), said device including at least one individual reservoir containing a single dose of fluid, such as powder, opening means (80) being provided for opening an individual reservoir each time the device is actuated, an upper body (101) being mounted in stationary manner on said main body (10), said upper body (101) receiving a mouthpiece (200) that defines a dispenser orifice, said device including an inhalation trigger system (60) that comprises a deformable air chamber (61) that co-operates with said inhalation piece (200), and a trigger element (600) that co-operates with said air chamber (61), such that during inhalation through said inhalation piece (200), said air chamber (61) is deformed and said trigger element (600) actuates said opening means (80), such that during inhalation through the inhalation piece (200), a reservoir is opened by said opening means, the fluid dispenser device being characterized in that said mouthpiece (200) is fastened to said upper body (101), said mouthpiece including a deformable peripheral lip (209) that, after assembly, co-operates in leaktight manner with a peripheral edge (108, 109) of said upper body (101).
