An inhaler (1) for halotherapy has in an axial direction (A) a proximal end (P) for insertion into the mouth of a user, and a distal end (D) opposite to the proximal end, wherein the inhaler comprises an inlet (4), an outlet (5) arranged at the proximal end, an air passage (10, 11, 12, 13) extending from the inlet to the outlet, and a reservoir (8, 9) communicating with the air passage through a release orifice (6, 7). The reservoir contains a dispersible substance, such as micronized salt. The inhaler has a proximal part (2) comprising the outlet, and a distal part (3) attached to the proximal part, wherein the proximal part is slidable in the axial direction with respect to the distal part between an 'OPEN' position and a 'CLOSED' position. The inhaler further comprises an inlet valve member (14), an outlet valve member (15), and a reservoir valve member (16, 17). The inlet valve member, outlet valve member and reservoir valve member are arranged so as to simultaneously close the inlet, the outlet, and the release orifice when the proximal part is brought from the 'OPEN' position into the 'CLOSED' position, and to simultaneously open the inlet, open the outlet, and deliver an amount of the dispersible substance from the reservoir through the release orifice to the air passage when the proximal part is brought from the 'CLOSED' position into the 'OPEN' position.
