An injection device is disclosed which comprises a housing (140, 240, 440, 740) for a plurality of cartridges (110,310,410,810) each containing a medicament to be administered to a patient. A plurality of needles (120, 220, 320, 420, 720, 820) may be provided in communication with the plurality of cartridges. A delivery mechanism is arranged to deliver medicament through the plurality of cartridges via the plurality of needles. An injection device may comprise a drive member (130) having a cam surface (136) configured to engage a surface of a carrier (150) and rotate the carrier about a pivot (152) and at least one plunger (134) arranged to engage a cylinder in the cartridge.