A dispenser device for dispensing a fluid or powder composition, including a dispenser outlet, an air expeller, and a reservoir containing a dose of a composition. The reservoir includes an air inlet connected to the air expeller, and a composition outlet connected to the dispenser outlet. The air inlet includes a composition retainer member for retaining the composition in the reservoir until the composition is dispensed, and the composition outlet being closed by a closure element that is force fitted in the composition outlet of the reservoir. The device includes a mechanical opening system that co-operates with the closure element so as to expel it mechanically from its closed position while the device is actuated. The closure element is an element that is not spherical, including a rounded portion, in particular a hemi-spherical portion, that faces towards the inside of the reservoir in the closed position.
