The present invention relates to a cartridge for a drug delivery device being at least partially filled with a medicinal product to be dispensed by the drug delivery device, the cartridge comprising - a sidewall (18) of substantially tubular shape, - a proximal end section sealed by an axially displaceable piston (20), - a distal end section sealed by a seal (24) and being penetrable by a piercing element (28), wherein the diameter or the surface of a pierceable section of the seal (24) is smaller than 30 %of the diameter or cross section confined by the tubular section of the sidewall (18).
