A single-use container for fluid products, comprising: - a containment body for a fluid product, provided with a neck ending in a dispensing mouth, and with a shoulder arranged below the neck and having a greater diameter than said neck; - a closing means which in an initial configuration is joined to said containment body along a predetermined breaking line to close the dispensing mouth and in an opening configuration, obtained by tearing said predetermined breaking line, is separated from said containment body to open said dispensing mouth; - an opening key which in the initial configuration is slidingly fitted onto the closing means and is rotationally disconnected therefrom and in a working configuration is prismatically rotationally engaged with said closing means to put pressure thereon and remove the closing means from said containment body to obtain the opening configuration; said opening key comprising a gripping portion and a connection portion having an end edge, wherein in the initial configuration the connection portion extends up to the beginning of the shoulder, and wherein, when the end edge meets the shoulder of the containment body, due to an axial compression force acting on the opening key, it deforms elastically, thus generating an upward thrust force in the direction of the prismatic decoupling between the opening key and the closing means; - at least one axial counterthrust means for the prismatic decoupling between the opening key and the closing means, activated by an axial compression force acting on the opening key, wherein the end edge is the axial counterthrust means; characterized in that the end edge of the connection portion is cylindrical, uniform and free from interruptions. - a containment body for a fluid product, provided with a neck ending in a dispensing mouth, and with a shoulder arranged below the neck and having a greater diameter than said neck; - a closing means which in an initial configuration is joined to said containment body along a predetermined breaking line to close the dispensing mouth and in an opening configuration, obtained by tearing said predetermined breaking line, is separated from said containment body to open said dispensing mouth; - an opening key which in the initial configuration is slidingly fitted onto the closing means and is rotationally disconnected therefrom and in a working configuration is prismatically rotationally engaged with said closing means to put pressure thereon and remove the closing means from said containment body to obtain the opening configuration; said opening key comprising a gripping portion and a connection portion having an end edge, wherein in the initial configuration the connection portion extends up to the beginning of the shoulder, and wherein, when the end edge meets the shoulder of the containment body, due to an axial compression force acting on the opening key, it deforms elastically, thus generating an upward thrust force in the direction of the prismatic decoupling between the opening key and the closing means; - at least one axial counterthrust means for the prismatic decoupling between the opening key and the closing means, activated by an axial compression force acting on the opening key, wherein the end edge is the axial counterthrust means; characterized in that the end edge of the connection portion is cylindrical, uniform and free from interruptions.