A piston rod (102) for a drug delivery device (101) is provided, comprising a first thread (103) with a first inner diameter (107) and a second thread (104) with a second inner diameter (108), wherein the first inner diameter (107) of the first thread (103) is smaller than the second inner diameter (108) of the second thread (104), and wherein the first thread (103) comprises a first pitch (105) and the second thread (104) comprises a second pitch (106), wherein the first and the second pitch (105, 106) have the same magnitude. Furthermore, a drug delivery device (101) is provided, the drug delivery device comprising a piston rod (102).
