There is provided a smoking article having an aerosol generating substrate and a mouthpiece. The mouthpiece includes a cavity at least partially filled with a particulate material, such as activated carbon,and contains at least one breakable capsule of a liquid flavourant at least partially surrounded by the particulate material, such that the force required to break the capsule within the mouthpiece to release the liquid flavourant is less than three times the inherent burst strength of the capsule.