The invention provides an inhalation device comprising a base unit, a mouthpiece, and an aerosol head. The base unit comprises an air inlet, an air outlet opening, a groove for receiving the mouthpiece, and key lock member(s). The mouthpiece comprises a first segment, comprising an air inlet opening and a lateral opening for receiving an aerosol generator, the first segment being insertable into the groove of the base unit, and a second segment comprising an aerosol outlet. The aerosol head comprises an aerosol generator, a liquid reservoir, and key lock member(s) complementary to the key lock member(s) of the base unit. The base unit, mouthpiece and aerosol head are connectable with one another such that when engaging the members of the key lock with the complementary members, the aerosol generator is inserted into the lateral opening of the mouthpiece.
