A dry powder inhaler comprises: a cyclone chamber having a cyclone chamber outlet (20) extending substantially axially therefrom; a mouthpiece channel (26) having a central axis; and a plenum portion (58) connecting said cyclone chamber outlet (20) and said mouthpiece channel, the mouthpiece channel axis Am being offset from, and making a non-parallel angle with, the axis of the cyclone outlet Ac such that in use air exits the cyclone outlet (20) at least partly tangentially into the mouthpiece (28). Also disclosed is a blister pack (200) for use with a dry powder inhaler and including a dose of powder for inhalation, the blister comprising: a base part (202) comprising at least one chamber (204,206); a grommet cover (208) extending partly over said chamber and defining an aperture (212, 214) above the chamber; and a protective layer (210) covering at least said aperture, wherein the edge of the grommet cover (208) defining the aperture (212, 214) is compliant so as in use to form a seal around a tube passing through the aperture.