A co-injection nozzle for an injection moulding device for producing multi-layered injection-moulded products. The nozzle includes: a central bore; a valve needle for opening and closing a nozzle opening; an annular inner melt channel for the first melt; an annular central melt channel for a second melt; and an annular outer melt channel for the first melt. The inner, central and outer melt channels are fluidically combined in the region of the nozzle tip to form a concentrically-layered melt stream. The co-injection nozzle has a back-flow barrier, integrated into the central bore, for the second melt, this barrier formed by a cut-out in the valve needle and by a melt channel for the second melt, the channel penetrating the central bore. In the open position of the back-flow barrier, the cut-out is located such that the second melt can flow through the melt channel, whilst flowing in the central bore past the valve needle.