The present invention relates to a drug delivery (5) comprising a housing (10) with a proximal end (30) and a distal end (22), a cartridge holder (14) adapted to retain a cartridge (16), the cartridge holder (14) comprising an at least partially transparent side wall (36), a piston rod (26), the piston rod (26) being adapted to drive a piston so as to engage the piston (28) into the cartridge (16), anda plurality of symbols (32) on the piston rod (26), the symbols (32) representing dosage information during operation of the drug delivery device (5) and being visible through a window aperture (40) in the housing (10) or in the cartridge holder (14). Furthermore, using a plurality of symbols (32) on a piston rod (26) to represent dosage information during operation of the drug delivery device (5) is disclosed.
