An inhaler device having an opening device for opening an individual reservoir containing a single dose of fluid, such as powder, the reservoir including a closure wall, the opening device having hollow perforator mechanism that is adapted to perforate the closure wall of the reservoir, the hollow perforator mechanism being connected to an expulsion channel so as to transport the powder towards a dispenser orifice of the inhaler. The opening device includes at least one air channel connected to the expulsion channel, such that during inhalation, an air flow passing through the at least one air channel mixes, in the expulsion channel, with the air and powder flow leaving the reservoir through the hollow perforator mechanism. The air channel is formed by a through hole made in a wall of the perforator mechanism, the through hole being oriented substantially parallel to the expulsion channel.
