There is provided a cartridge assembly (10) for use in an aerosol-generating system, the cartridge assembly (10) comprising a mouthpiece housing (12), a blocking element (26) and a cartridge (14). The mouthpiece housing (12) has an upstream end (28), a downstream end (16), and a mouthpiece cavity (20). The blocking element (26) is secured within the mouthpiece cavity (20). The cartridge (14) is positioned at the upstream end (28) of the mouthpiece housing (12), the cartridge (14) comprising an upstream end, a downstream end, a first compartment (44) and a second compartment (46). The downstream end of the cartridge (14) abuts an upstream end of the blocking element (26). The cartridge (14) is rotatable with respect to the blocking element (26) from a first position to a second position. In the first position the blocking element (26) obstructs first and second air outlets (92, 94) of the first and second compartments (44, 46) respectively. In the second position the first and second air outlets (92, 94) are in fluid communication with the mouthpiece cavity (20).
